ASSOCIATION BETWEEN MICROALBUMINURIA AND DIABETIC ...
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i
ASSOCIATION BETWEEN MICROALBUMINURIA AND DIABETIC
RETINOPATHY IN TYPE 2 DIABETES PATIENTS . A ONE YEAR CROSS –
SECTIONAL STUDY
BY
DR. N. RAHUL NAGMBBS
Dissertation Submitted to the
Rajiv Gandhi University of Health Sciences, Bengaluru, Karnataka.
In partial fulfillment
of the requirements for the degree of
DOCTOR OF MEDICINE
in
GENERAL MEDICINE
Under the Guidance of
DR. SIDDALINGA REDDYMD
ASSOCIATE PROFESSOR
DEPARTMENT OF GENERAL MEDICINE
NAVODAYA MEDICAL COLLEGE, HOSPITAL AND
RESEARCH CENTRE, RAICHUR -584103
2011
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RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES,
KARNATAKA, BANGALORE
DECLARATION BY THE CANDIDATE
I hereby declare that this dissertation/thesis entitled “ASSOCIATION
BETWEEN MICROALBUMINURIA AND DIABETIC
RETINOPATHY IN TYPE 2 DIABETES PATIENTS – A ONE YEAR
CROSS-SECTIONAL STUDY” is a bonafide and genuine research work carried
out by me under the guidance of Dr. SIDDALINGA REDDY, MD., Associate
Professor, Department of General Medicine, Navodaya Medical College, Hospital &
Research Centre, Raichur.
Date: Dr. N. RAHUL NAG
Place: Raichur
III
RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES,
KARNATAKA, BANGALORE
CERTIFICATE BY THE GUIDE
This is to certify that the dissertation entitled “ASSOCIATION
BETWEEN MICROALBUMINURIA AND DIABETIC
RETINOPATHY IN TYPE 2 DIABETES PATIENTS – A ONE YEAR
CROSS-SECTIONAL STUDY” is a bonafide research work done by Dr. N.
RAHUL NAG in partial fulfillment of the requirement for the degree of DOCTOR
OF MEDICINE IN GENERAL MEDICINE.
Date:
Place: Dr. Siddalinga Reddy MD. (General Medicine)
Associate Professor,
Dept. of General Medicine
Navodaya Medical College, Raichur
IV
RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES,
KARNATAKA, BANGALORE
CERTIFICATE BY THE CO-GUIDE
This is to certify that the dissertation entitled “ASSOCIATION
BETWEEN MICROALBUMINURIA AND DIABETIC
RETINOPATHY IN TYPE 2 DIABETES PATIENTS – A ONE YEAR
CROSS-SECTIONAL STUDY” is a bonafide research work done by Dr. N.
RAHUL NAG in partial fulfillment of the requirement for the degree of DOCTOR
OF MEDICINE IN GENERAL MEDICINE.
Date:
Place: Dr. Anupama. T M.S.. (Ophth.)
Professor & Head,
Dept. of Ophthalmology
Navodaya Medical College, Raichur
V
RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES,
KARNATAKA, BANGALORE
ENDORSEMENT BY THE HOD, PRINCIPAL/ HEAD OF
THE INSTITUTION
This is to certify that the dissertation entitled “ASSOCIATION
BETWEEN MICROALBUMINURIA AND DIABETIC
RETINOPATHY IN TYPE 2 DIABETES PATIENTS – A ONE YEAR
CROSS-SECTIONAL STUDY” is a bonafide research work done by Dr. N.
RAHUL NAG under the guidance of Dr. SIDDALINGA REDDY, MD. (General
Medicine), Associate Professor, Department of General Medicine, Navodaya Medical
College.
Dr. S.S. ANTIN Dr.Khaja Naseeruddin Professor & Head. Principal
Dept. of General Medicine Navodaya Medical College,
Hospital & Research Centre, Raichur
Date: Date:
Place: Raichur Place: Raichur
VI
RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES,
KARNATAKA, BANGALORE
COPYRIGHT
DECLARATION BY THE CANDIDATE
I hereby declare that the Rajiv Gandhi University of Health Sciences,
Karnataka shall have the rights to preserve, use and disseminate this dissertation
/thesis in print or electronic format for academic /research purpose.
Date:
Place: Raichur Dr. N. RAHUL NAG
© Rajiv Gandhi University of Health Sciences, Karnataka.
VII
ACKNOWLEDGMENT
At the outset I thank the Lord, Almighty, for giving me the strength to perform all
my duties.
It is indeed a great pleasure to recall the people who have helped me in
completion of dissertation. Naming all the people who have helped me in achieving this
goal would be impossible, yet I attempt to thank a select few, who have helped me in
diverse ways.
It gives me immense pleasure to express my deep sense of gratitude and
indebtedness that I feel towards my teacher and guide Dr. Siddalinga Reddy, MD,
General Medicine, Associate Professor, Department of General
Medicine,Dr.Anupama.T MS Ophthalmology Professor and Head for their valuable
suggestions, guidance, great care and attention to detail that he has so willingly shown in
the preparation of this dissertation.
I acknowledge and express my humble gratitude and sincere thanks to my beloved
teacher Dr.S.S. Antin, MD., General Medicine, Professor and H.O.D., for his constant
help to undertake this study
I owe a great deal of respect and gratitude to Dr.Chaitanya Kumar Swamy, MD,
General Medicine, Associate Professor, Dr. Krishna Prasad, MD, General Medicine,
Associate Professor, Dr.Ajit Kumar , MD, General Medicine, Associate Professor,
Dr.Ramakrishna. M.R., MD, General Medicine, Assistant Professor, Dr.N.S. Javali,
MD, General Medicine, Assistant Professor, Dr. Imran, General Medicine, Assistant
Professor, Dr. Amar S. Patil, General Medicine, Assistant Professor, Dr. Anand
Chaudhuri, General Medicine, Assistant Professor, Dr. S.S. Reddy, General Medicine,
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Assistant Professor, Dr. Vinay, General Medicine, Assistant Professor, Dr. Praveen
Bhadri, General Medicine, Assistant Professor, Navodaya Medical College, Raichur, for
their scholarly suggestions and all round encouragement.
I am extremely grateful to Dr. Khaja Naseeruddin, M.S (ENT)., Principal, and
Dr.S.R.Hegde, M.S.,Medical Director, Navodaya Medical College, Raichur, for their
valuable help and co-operation.
I am also thankful to my colleagues Dr. Novak Gupta, Dr. Deepak, Dr. Kavya,
Dr. Soumya, Dr. Darshana, Dr. Hardhik Gajera, Dr. Aniket Kataria, Dr. Harsha
Totad, Dr. Praveen Paul, Dr. Swathi, Dr. Dasrathi for their constant voluble help and
co-operation and encouragement to complete this dissertation.
I express my sincere thanks to Superintendent and Resident Medical Officers of
Navodaya Medical College Hospital for their valuable help and cooperation.
Finally, I thank all my patients who formed the back bone of this study without
whom this study would not have been possible.
Date:
Place: Dr. N. Rahul Nag
IX
LIST OF ABBREVIATIONS USED
ACE: Angiotensin Converting Enzyme
AER: Albumin Excretion Rate
AGE: Advanced Glycosylation Products
BMI: Body Mass Index
FBS: Fasting Blood Sugar
GAG: Glycosaminoglycans
GFR: Glomerular Filtration rate
HDL: High Density Lipoproteins
HTN: Hypertension
Ig: Immunoglobulin
IL: Interleukin
IGF: Insulin like Growth Factor
IHD: Ischemic Heart Disease
LDL: Low Density Lipoprotein
NIDDM: Non Insulin Dependent Diabetes Mellitus
PAS: Periodic Acid Schiff
PDGF: Platelet Derived Growth Factor
PPBS: Post Prandial Blood Sugar
PVD: Peripheral Vascular Disease
PN: Peripheral Neuropathy
TGL: Triglycerides
VLDL: Very Low Density Lipoprotein
X
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ABSTRACT
Background: Diabetes Mellitus is one of the most common chronic disorders and the
commonest metabolic disease affecting man. The incidence of this disease is increasing
all over the world. The magnitude of the problem is compounded by the various
complications targeting vital organs. Diabetic nephropathy is the leading cause of End
Stage Renal Disease in the world, accounting for more than one third of the cases. About
25 to 40% of type 2 diabetics will develop nephropathy eventually. The earliest evidence
of nephropathy is microalbuminuria. The association between microalbuminuria and
diabetic retinopathy is closely related and can be useful in preventing or delaying the
occurrence of diabetic retinopathy. Microalbuminuria is a marker of wide spread
microvascular damage in Type 2 diabetes mellitus. The association between overt
proteinuria and proliferative diabetic retinopathy have been demonstrated and there is
increasing evidence that microalbuminuria could be a marker of early diabetic
retinopathy.
Objectives:
To study the prevalence of microalbuminuria in Type 2 diabetes mellitus.
To study the association between microalbuminuria and diabetic retinopathy in
Type 2 diabetics.
Methods: A cross-sectional study over a period of one year. 100 cases those attending
the OPD and medical wards of Navodaya Medical College, Raichur, were enrolled for
the study.
Results: Out of 100 cases 57 cases were male and 43 cases were female.
Microalbuminuria was found in 38% of patients and diabetic retinopathy was present in
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44% of patients.Microalbuminuria and diabetic retinopathy was present in 31% of
patients showing that there is association between microalbuminuria and diabetic
retinopathy.
Microalbuminuria and retinopathy was found more for the age group above 50years
(p=0.053,0.001).
Conclusion:
The present study has shown that there is significant association between the
presence of microalbuminuria and retinopathy.
It has also shown that there is increase in the prevalence of microalbuminuria and
retinopathy with increasing age ,HbA1c >7%,BMI>25 Kg/m2
.
Key words: Diabetic Retinopathy, Microalbuminuria
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TABLE OF CONTENTS
1. INTRODUCTION ............................. 1-2
2. AIMS AND OBJECTIVES ................................ 3
3. REVIEW OF LITERATURE ........................... 4-42
4. MATERIALS & METHODS ......................... 43-47
5. OBSERVATION & RESULTS ......................... 48-59
6. DISCUSSION ......................... 60-64
7. CONCLUSION .............................. 65
8. SUMMARY .............................. 66
9. BIBLIOGRAPHY ......................... 67-80
10. ANNEXURES
* INFORMED CONSENT .............................. 81
* PROFORMA ......................... 82-89
* MASTER CHART ......................... 90-94
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LIST OF TABLES
Sl.
No. Titles
Page
No.
1. Table showing age and sex distribution 48
2. Table showing number of patients with microalbuminuria and
retinopathy 50
3. Association of age with microalbuminuria and retinopathy
51
4. Association of duration of diabetes with microalbuminuria and
retinopathy 53
5. Association of HbA1c with microalbuminuria and retinopathy
55
6. Association of BMI with microalbumiuria and retinopathy
57
7. Association between microalbuminuria and retinopathy
59
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LIST OF GRAPHS
Sl.
No. Titles
Page
No.
1. Table showing age and sex distribution 49
2. Table showing number of patients with microalbuminuria and
retinopathy
50
3. Association of age with microalbuminuria and retinopathy 52
4. Association of duration of diabetes with microalbuminuria and
retinopathy
54
5. Association of HbA1c with microalbuminuria and retinopathy 56
6. Association of BMI with microalbumiuria and retinopathy 58
7. Association between microalbuminuria and retinopathy 59
XVI
LIST OF FIGURES
Fig.
No. Titles
Page
No.
1 MICRAL Test Strip – II 32
2 Background Diabetic Retinopathy showing scattered exudates and
haemorrhages near fovea
40
3 Background Retinopathy with severe Maculopathy and hard
exudates at macula
40
4 Proliferative Diabetic Retinopathy with disc Neovascularisation 41
5 Advanced Proliferative Diabetic Retinopathy with Tractional
Retinal detachment
41
6 Proliferative Diabetic Retinopathy with abnormal vessels at optic
disc and retina with early vitreous haemorrhage
42
1
INTRODUCTION
Diabetes mellitus, the most common endocrine disorder is characterised by
metabolic abnormalities and long-term microvascular and macrovascular
complications.
The prevalence of diabetes is on the rise, more alarmingly in the developing
countries. Besides multiplying risk for coronary heart disease, diabetes enhances the
incidences of cerebro vascular accidents. Moreover it is the leading cause of acquired
blindness and accounts for about a quarter of the cases with end stage renal disease as
well as half of the cases of non-traumatic lower limb amputations.
Diabetic nephropathy occurs in as many as 30% of insulin dependant diabetes
mellitus patients and 25% of non-insulin dependent diabetes mellitus patients.
Diabetic nephropathy is a dreaded disease with progressive and continuous
deterioration in glomerular function resulting in irreversible renal failure. Diabetic
nephropathy is an important cause of morbidity and mortality and is now among the
most common cause of end stage renal disease. However there is an early phase of
diabetic renal disease called incipient diabetic nephropathy. In this stage, there is a
rise in urinary excretion of albumin i.e. microalbuminuria. But the rise is detectable
only by use of sensitive assay for urinary albumin. At this stage urine is negative for
macro albumin and renal function is normal by standard clinical tests. The presence of
microalbuminuria precedes the development of overt diabetic nephropathy by 10 to
15 years. It is at this stage that one can hope to reverse diabetic renal disease or
prevent its progression. Therapeutic interventions which reverse microalbuminuria
2
include intensified insulin treatment, dietary protein restriction and control of
hypertension by ACE inhibitors and Beta-blockers.
Microalbuminuria thus is an important warning sign for both the physician and
the patient which if ignored can lead to irreversible renal damage.
Microalbuminuria is most commonly associated with other microvascular
complications of diabetes namely retinopathy, neuropathy, and ischemic heart disease.
So, microalbuminuria may be a marker for widespread microvascular damage in a
patient of diabetes mellitus.
The aim was to study the occurrence of microalbuminuria in patients with
non-insulin dependant diabetes mellitus and also to find out its association with the
duration of diabetes mellitus and retinopathy.
3
OBJECTIVES
To study the prevalence of microalbuminuria and retinopathy in type 2
diabetes mellitus.
To study the association between microalbuminuria and retinopathy in type2
diabetes mellitus.
4
REVIEW OF LITERATURE
HISTORICAL REVIEW:
1. Diabetes mellitus:
The knowledge of diabetes dates back to centuries before Christ. Polyuric
disease, resembling diabetes was described as early as 150 BC in ancient Egyptian
records discovered by George Beers. Celsius (30BC-50AD) had recognized the
disease. Diabetes, a Greek term, which literally means to „run thru‟ or a „siphon‟ was
initially used by Aretaeus in first century AD for the generic description of a
condition causing increased urine output1. Roman physicians thought of diabetes as a
“wonderful affection, not very frequent among men, being melted down of flesh and
limbs into urine. The patient never stopped making water, but the flow is incessant as
if from a opening of aqueducts- Aretaeus, the Cappadocian2,3
.
The association of polyuria with a sweet tasting substance in the urine was
first reported in Sanskrit literature dating from fifth to sixth centuries AD at the time
of two noted Indian physicians Susruth and Charaka.
It was in the seventeenth century that Thomas Willis (1621-1675) made the
observation “as if imbibed with honey and sugar about the diabetic urine”. A century
after Willis, Mathew Dobson (1735-1784) demonstrated that the sweetness of urine
was indeed due to sugars. It was John Rollo who was one of the first to use the
adjective mellitus (mellitus = honey) to distinguish it from other polyuric states in
which the urine was unsavory (Greek – insipidus). Over the centuries, gradually the
causes and complications of this disease were recognized. Aricanne, an Arab
physician at around the tenth century had described gangrene2,3
.
5
The diabetes world was overwhelmed with joy in 1921 when young physician
and surgeon Fredrick Grant Banting (1891-1941) and Charles.H.Best, his graduate
student assistant, working in Toronto through the summer on an almost non-existent
budget in a lab loaned to them temporarily by a vacating professor, prepared active
extracts of pancreas which lowered the elevated level of sugars in diabetic dogs. The
first patient to be treated with pancreatic extract was Leonard Thomson in 1922.The
long acting insulin preparation (isophane) was introduced in 1936 by Hans Christian
Hagedorn and his colleagues. The testing of Sulfonylureas was done by Auguste
Loubatieries in 1944.The first therapeutic use of a Biguanide was done by G.Ungar in
1957.The efficacy of insulin in preventing the complications and retarding
multisystem involvement was heralded by the fact that the untreated cases in the pre-
insulin era had a high mortality rate which was mostly due to diabetic ketoacidosis2,3
.
2. Diabetic nephropathy:
Diabetes was for many years regarded as the disease of the kidneys. This was
the opinion of Aretaeus, Capadcian in second century AD. The view was still held by
Erasmus Darwin in 1801. The presence of proteinuria in diabetes mellitus had long
been known. Contunniues (1770), Rollo (1798), Darwin (1801), Rayer (1840), Van
Noorden (1912), all had described the association of dropsy with diabetes.
Vacuolization of tubular epithelium was observed by Armani (1875) and Ebstein
(1881) and was shown to be due to glycogen infiltration by Ehlrich in 1888.
Kimmelstiel and Wilson were the first to attribute specific glomerular lesions
entitled inter capillary lesions in the glomeruli of kidney. These peripheral hyaline
masses are known as Kimmelstiel Wilson lesions. These histological features were
6
associated with clinical features of diabetes, hypertension, nephrotic syndrome and
renal failure. Fahr demonstrated soon after the diffuse lesions in 1942.
Several major studies among diabetics have been undertaken (Tuft et al 1956,
Farqahar et al 1959, Gellman et al 1959, Hatch et al 1961, O Sullivan et al, Thomsal)
and proteinuria especially when diffuse changes are considered. On the whole,
advanced clinical disease is accompanied by severe glomerular lesions5.
3. Microalbuminuria:
In 1963,Keen and Chlouvervakis developed sensitive and specific
Radioimmunoassay for detecting human albumin in low concentration i.e.
microalbuminuria, which indicate earliest stage of diabetic renal disease. Later
various other methods were developed for detection of microalbuminuria6.
DEFINITION AND PATHOPHYSIOLOGY
Microalbuminuria:
This means significant increase in albumin excretion rate (AER). Albumin
excretion in healthy individuals ranges from 1.5 to 20 mcg/min with geometric mean
in the range of 6.5mcg/min, these have been termed normoalbuminuria.
Microalbuminuria thus defines the wide substantial range of albumin hyper secretion
ranging between 20to 200mcg/min (30 to 300mg/day)7. Normal persons excrete less
than 30 mg /day. Microalbuminuria is not detected by reagent sticks for urinary
protein which generally becomes positive only when proteinuria is greater than 550
mg/day. This degree of leakage is termed macroalbuminuria8,9
.
7
In 1963, Keen and Chlouvervakis developed sensitive specific
radioimmunoassay for detecting human albumin in low concentration in urine to
study the sub clinical increase in urine albumin excretion rate (AER), which might be
the earliest pointer to the development of diabetic renal disease6.
A significant increase in mean AER was demonstrated in non insulin
dependant diabetic subjects newly detected in population survey by Keen in 1969.
This AER was an average three to four times above the normal level. Later
Mongensen et al in 1971 found increased AER in newly diagnosed youngsters with
insulin dependent diabetes mellitus as did Parving et al in short term insulin
dependent diabetes mellitus patients whose control had been deliberately worsened by
withdrawal of insulin for some days. In established conventionally treated adult
insulin dependent diabetes mellitus, patients known to be diabetic between 6 months
and 39 years, albumin and IgG excretion rates were found to be raised in 30 to 45%
patients especially those patients with duration of diabetes between 10 and 20 years8.
Term Synonym Urinary Albumin Excretion
Normoalbuminuria ----- <20 mcg/min
Microalbuminuria Incipient nephropathy 20-200 mcg/min
Macroalbuminuria
Clinical Nephropathy/
Overt Nephropathy
>200 mcg/min
Histopathology of kidney in normal individuals and diabetes10
:
The main pathological features of diabetic kidney disease occur in the
glomerulus.
8
Normal subject:
Glomerulus consists of tuft of 20 –40 capillary loops, which arise from an
afferent and drain into an efferent arteriole. Mesangial tissue, comprising both cellular
and matrix components, support lobules of capillaries. Electron microscopy of the
loops shows that each loop consists of a basement membrane lined by fenestrated
endothelium and covered by visceral epithelial cells (podocytes) carrying foot
processes that interdigitate along the membrane, leaving spaces (filtration slits or
pores) between the processes. The Bowman‟s capsule encloses the glomerular tuft,
which is continuous with the tubular basement membrane and binds the urinary space.
Filtration of plasma proceeds from the capillary, across the endothelium (probably via
the fenestrae),the basement membrane, through the slit pores of the epithelium and
into the urinary space and the proximal tubule11
.
Changes in diabetes:
In diabetes, the volume of the whole kidney and of individual glomeruli is
increased at the time of diagnosis12
and glomeruli continue to enlarge later in the
disease12,13
. Early glomerular enlargement is probably due to enhanced basement
membrane production leading to an increased in filtration surface area while later
expansion may be caused due to mesangial expansion14
. The increase in total renal
volume is likely to be caused by tubular tissue. In diabetic nephropathy, renal size is
therefore usually normal or large even when end stage renal failure develops, which is
in contrast to most causes of chronic renal failure in which renal size tends to decrease
with advancing disease. In some cases however, concomitant to a reduction renal
artery stenosis or upper urinary tract infections may contribute in overall renal size15
.
9
Basement membrane thickening has long been recognized as a pathological
hallmark of diabetes16
. Thickening can be detected within two years of the detection
of diabetes mellitus17
. Marked thickening occurs in patients with diabetes for duration
more than 10 years18
. Mesangial expansion seems to occur after the thickening of the
glomerular basement membrane, although this may not be the true sequence of events
because it is technically easier to detect changes in basement membrane thickness
than in the mesangium19,20
. Matrix accumulation rather than cellular increase accounts
for most mesangial expansion21
. Unlike basement membrane thickening, mesangial
volume may be normal in some patients after 25 years of diabetes, although those
with established nephropathy invariably have mesangial expansion18
.
Nodular lesions consisting of ovoid accumulations of periodic acid schiff
(PAS) positive material, often occupying the central mesangium of a lobule, is almost
pathognomonic of diabetes22
. When advanced, these changes are referred to as the
Kimmelstiel-Wilson kidney. Hyaline deposits also occur as eosinophilic, acellular
material but are non- specific and are found in several other renal conditions. They
can be present inside Bowman‟s capsule („capsular drop‟), between the endothelial
cell and basement membrane („fibrin cap‟), and in the afferent and efferent arterioles.
Global glomerular sclerosis or occlusion, caused by mesangial expansion or ischemia
secondary to afferent arteriolar blockage, is a feature of patients with declining GFR.
As in other types of progressive renal disease, the tubules and interstitium may show a
variety of non-specific changes22,23
.
The origin and determinants of microalbuminuria24
:
Of the small quantity of albumin and IgG normally filtered at the glomerulus,
95to 97% is reabsorbed by proximal tubules. The reabsorptive process works near
10
maximal capacity. So that moderate increase in filtered protein is reflected in an
elevation of its urinary excretory rate. If reabsorption is proportional to the filtered
load, then the excretion of albumin and IgG in the urine will change proportionally
with amount filtered, when the tubular reabsorption capacity is saturated, urinary
protein excretion will parallel filtration.
The fact that the microalbuminuria and microIgGuria of the diabetes both at
rest and response to exercise is glomerular in origin and associated with normal
tubular is supported by the findings of a normal β2 microglobulin (molecular weight
11,800 Daltons, stokes radius 16Ao) a sensitive indicator of tubular reabsorptive
capacity.
Tubular proteinuria is characterised by large increase in β2-microglobulin
excretion with small changes in albumin excretion. The moderate increases of β2-
microglobulin excretion that have been reported in diabetes have been under
conditions of extremely poor metabolic control and ketosis.
The glomerular capillary blood urine barrier can be regarded functionally as
membrane, perforated by pores of average size 555Ao and uniformly coated by
negative electric charge. Therefore the size and charge of circulating molecules as
well as transglomerular pressure gradient, the force during glomerular filtration of
macromolecules will determine the passage of protein across the barrier. In
microalbuminuric diabetic subjects, the clearance of albumin, a polyanion (PL, 48
mol.wt 49,000 stokes radius 36Ao) and IgG, a larger but electrically neutral molecule
(PL 7.5-7.8 mol.wt. 1,60,000 stokes radius 55Ao) are both increased, these early
increases are likely to be a consequence of alteration in glomerular haemodynamics,
and in particular of transglomerular pressure gradient.
11
In a diabetic patient,the enlarged filtration surface area would probably result
in greater number of pores (no larger pores have been shown at this stage of diabetes)
and influences the filtration of plasma proteins.
As microalbuminuria becomes persistent and increases in degree, the
sensitivity index i.e. clearance of IgG/clearance of albumin starts to fall reaching its
lowest values when albumin excretion is around 90 mcg/min or higher. This is due to
disproportionate increase in filtration of albumin compared with IgG, and it marks a
new selective stage of glomerular leakage of anionic albumin. At this stage, medium
sized pores are unchanged and the likely reason for the increased glomerular albumin
filtration is a loss of fixed negative electrical charge on the membrane. This would
permit increased permeation of anionic albumin but have little influence on IgG, a
neutral molecule the filtration of which is regulated by pore radius or number and
intraglomerular pressure.
The mechanism of this transition from low to high levels of microalbuminuria
is unknown; but may be a combination of deleterious effects of long-term elevation of
intraglomerular pressure and flow with cumulative metabolic abnormality of synthesis
of electronegative membrane glycosialoprotein and proteoglycans. Moreover the
recent reports indicate that the glycosylated proteins including albumin undergo the
preferential transport across the glomerular membranes. The reason for this facilitated
flux of glycosylated macromolecules through the glomerular barrier is unknown. The
transition to high selectivity proteinuria signifies the advent of heavier proteinuria.
This indicates the critical importance of loss of charge barrier in unfolding sequence
of pathogenic events.
12
Concomitants of microalbuminuria24
:
In diabetic humans, there is no correlation between glycosuria and urinary
albumin excretion. Whether acute worsening of glycemia by glucose ingestion or
infusion increases AER remains controversial. Glucose ingestion has been reported to
increase albuminuria in normal subjects but not in diabetic patients. A number of
studies have failed to show any acute effects on either oral or intra venous glucose on
urinary albumin excretion. Mild metabolic acidosis has no effect on urinary albumin
excretion but increases the excretion of β2 microglobulin. Neither growth hormone
nor glucagons affect albumin excretion in normal or in diabetic subjects.
A consistent association of microalbuminuria is found with higher level of
arterial pressure. Many investigators have confirmed a positive linear and independent
correlation between arterial pressure and AER. Furthermore, changes in blood
pressure have been shown to be positively correlated to changes in AER in a
prospective study. The association is much more closer than between AER and blood
glucose levels and independent of number of other variables including age, sex,
duration of diabetes, body mass index and blood glucose levels itself.
The observation of higher arterial pressure in microalbuminuric patients
without reduced GFR speaks against the assumption that higher blood pressure is
consequence of renal dysfunction and argues in favour of more complex relationship.
This raises the possibility that either the rise in blood pressure could be contributory
to renal disease or alternatively that microalbuminuria and higher blood pressure may
be related to a common determinant. It is of interest that microalbuminuric patients
with elevation of arterial pressure show significantly more marked mesangial
expansion than patients with lower AER and arterial pressure.
13
Macroproteinuria:
The appearance of macroproteinuria in an insulin dependent diabetic subject
initiates the phase leading through progressively declining renal function to end stage
renal failure. The GFR may be normal or even raised at the onset of macroproteinuria,
but will proceed relentlessly to fall, its rate of decline ranging from 0.6 to 2.4
ml/min/month. Urinary protein increases as the GFR falls and a highly significant
negative correlation has been found between GFR on one hand and clearance of
albumin and the other. The 24-hour excretion of albumin correlates positively with
the urinary total protein excretion.
By the stage of macroproteinuria, albumin represents approximately 50% of
total urinary proteins. This is much higher proportion than that found in subjects with
normoproteinuria (upto11%) or microproteinuria (up to 22%). In individuals with
macroproteinuric phase,excretion of total protein varies considerably from day to day,
but the fractional clearance (i.e. clearance of a protein per unit of GFR) of individual
protein is much more stable and represents a more accurate index of residual
glomerular performance. The fractional clearance of albumin and IgG increases
progressively with time and in parallel with decline in GFR.
Origin of macroproteinuria and relation to glycemia:
The increasing proteinuria is primarily glomerular in origin, tubular
reabsorptive capacity for albumin soon becomes completely saturated and changes in
urinary excretion are then a more accurate reflection of changes in transglomerular
flux. The urinary excretion rates of low molecular weight proteins, such as β2
microglobulin or lysozyme, does not go up until glomerular function is markedly
depressed and their plasma levels have risen. Saturation of tubular reabsorptive
14
capacity in functioning nephrons with protein overload may cause the rising urinary
excretion rate rather than primary tubular dysfunction. Urinary clearance of β2
microglobulin rises exponentially as GFR falls below 40ml/min/1.73m2.
In contrast to microproteinuria, the degree of macroproteinuria shows no
relationship with current level of diabetic control. Neither the mean plasma glucose
concentration nor glycosylated haemoglobin levels correlated significantly with
clearance and excretion rates of different proteins. Long term correction of
hyperglycaemia by an intensified treatment regimens, failed to stop or significantly
slow the progressive increase in fractional clearance of albumin and IgG in insulin
dependent diabetic subjects with renal failure over a period of 2 years observation24
.
ETIOPATHOGENESIS
1. Hyperglycemia:
There is overwhelming evidence linking hyperglycemia to diabetic micro
vascular and macro vascular complications. In the kidney, histological changes such
as mesangial expansion may be reversed by transplantation of diabetic kidney in to a
normal animal or by correcting diabetes with islet cell transplantation.
2. Non-enzymatic glycosylation:
One possible link between elevated glucose levels and diabetic nephropathy is
through non-enzymatic glycosylation of cellular proteins.
There are three possible mechanisms through which non-enzymatic glycation
may contribute to diabetic complications.
15
1) AGE may alter the structure and functions of extracellular matrix by cross-
linking matrix proteins.
2) AGE may affect the activity of signals such as cytokines, growth factors and
free radicals, by interacting with AGE receptors on various tissues.
3) Glycation may directly affect the functions of enzymes and other key
intracellular proteins1,25
.
3. The polyol pathway:
Sorbitol is produced in cells from glucose by reaction catalysed by aldolase
reductase. In the normal kidney, aldolase reductase is present in the papilla,
glomerular epithelial cells, distal tubular cells and also in mesangial cells. In the renal,
medullary cells of the kidney the primary role of aldolase reduction is in the
generation of Sorbitol, an organic osmolyte in response to high salinity in medullary
interstitium. Sorbitol would aid in preventing the osmotic stress. Chronic
hyperglycemia may lead to Sorbitol accumulation in a variety of tissues including
renal tubules and glomeruli. Sorbitol accumulation could cause tissue damage perhaps
by disturbing cellular osmoregulation and depleting intracellular myoinositol.
Depletion of phospoinositidase may result in reduced hydrolysis of
phosphotidylinositol bi phosphate and decreased diacylglycerol formation.
Diacylglycerol is a major endogenous cellular mediator of protein kinase C activation
which itself has been implicated in pathogenesis of diabetic renal disease26
.
4. Biochemical abnormalities of extracellular matrix:
Diabetic glomerulopathy is characterised by excessive accumulation of
glomerular basement membrane and mesangial matrix. The activity of lysyl
hydroxylase, an enzyme involved in the hydroxylation of peptide bound lysine during
16
collagen biosynthesis is found to be increased in the glomeruli of diabetic rats.
Glycosaminoglycans (GAG), polysaccharides account for approximately 90% of total
carbohydrate component of glomerular basement membrane with sialoprotein
constituting remainder.
The principal GAG in the glomerular basement membrane is heparan sulphate
that together with sialic acid contributes to negative charge of glomerular capillary
wall and thereby to charge selective properties of the filtration barrier. In diabetes,
there is reduced de novo synthesis of glomerular heparan sulphate and the total GAG
content in the glomerulus and the glomerular basement membrane is reduced. The
heparan sulphate content of glomerular basement membrane has been found to be
decreased in patients with IDDM with nephropathy. Sialoglycoproteins are highly
negatively charged and coat glomerular epithelial cells, their foot process and
epithelial slit diaphragm. A loss of negative charge of glomerular membrane may be
responsible for foot process fusion, with consequent obliteration of the slit diaphragm
and could partly explain the albuminuria of diabetic nephropathy27
.
5. Glucotoxicity:
Glucose itself may have direct toxic effects on cells. Lorenzi et al have
demonstrated cultured human endothelial cells that are chronically exposed to high
glucose concentrations show important abnormalities in cell function, which cannot
be ascribed to polyol pathway activity. Abnormalities include alteration in cell
replication and maturation associated with evidence of damage to DNA. High glucose
levels also lead to increased expression and synthesis of collagen, fibronectin and
laminin, which may partly explain the enhanced products of extracellular matrix
observed in diabetic kidneys. Mesangial cells in high glucose levels induce
17
transcription and secretion of TGF-B, which is unique among the cytokines in that it
stimulates the matrix synthesis and inhibits its degradation. Abnormalities in
endothelial cell function have been implicated in the increased frequency of
cardiovascular disease which is a feature of diabetic nephropathy. It has been shown
that such abnormalities evidenced by raised plasma levels of Von Willebrand factor
and decreased release of tissue plasminogen activator in response to exercise are
present even before overt nephropathy develops28,29,30
.
6. Haemodynamic and hypertrophic pathways:
Glomerular hemodynamic disturbances with elevation of renal blood flow and
GFR occur early in the course of diabetes have been suggested directly responsible
for development of glomerulosclerosis and attendant proteinuria. Several observations
support the notion that renal hyper perfusion and hyper filtration contribute to renal
damage. Elevated intraglomerular pressure via increased mechanical stress and shear
forces may damage the endothelial surface and disrupt the normal structure of
glomerular barrier, and could eventually lead to mesangial proliferation, increased
production of extracellular matrix and thickening of glomerular basement
membrane26
.
7. Familial and genetic pathways:
Diabetes induces important metabolic, hormonal and growth factor changes.
These changes that are related in part to the degree of glycemic control, occur in
virtually all patients, but till now it has been impossible to isolate a subset of
individuals in whom the severity of these environmental perturbations is convincingly
linked to development of these complications. On the contrary, there is ever growing
evidence that the diabetic control is only a necessary component but is not linearly
18
related to the development of renal failure. To explain the susceptibility of renal
failure in a subgroup of patients who develop renal failure alternative hypothesis has
been advocated taking into account the host response to diabetic induced
environmental disturbances.
Familial clustering of diabetic kidney disease has been reported. In IDDM
83% of siblings of proband with diabetic nephropathy have evidence of nephropathy,
compared with only 17% of diabetic sibling of probands without nephropathy31
.
Familial influence on development of nephropathy has been described in Pima
Indians with NIDDM. A familial predisposition to raised arterial pressure has been
suggested by some reports as possible contributing factor to susceptibility to
nephropathy in diabetics32
.
Sodium Lithium counter transport:
Genetically determined red cell sodium-lithium counter transport, a cell
membrane cation transport system whose elevated levels are associated with essential
hypertension has given insight into predisposition to diabetic renal disease and also
attendant cardiovascular disease33
. The rate of sodium-lithium counter transport has
been found to be higher in proteinuric patients with diabetes than in
normoalbuminuric controls. Microalbuminuric diabetic patients have also been found
to have higher sodium-lithium counter transport activity. Higher rate of counter
transport were associated with elevated LDL cholesterol, total and VLDL,
triglycerides and reduced HDL cholesterol concentrations.
The mechanism of association between sodium lithium counter transport
activity, hypertension and lipid abnormalities and susceptibility to diabetic renal and
vascular disease could be insulin resistant state. These associations (i.e. albuminuria,
19
left ventricular and renal hypertrophy and insulin resistance) were independent of
actual level of blood pressure or duration of arterial hypertension. This combination
of risk factors may not be confined to diabetic population but may be a manifestation
of syndrome in general population (Syndrome X)34,35.
Sodium-hydrogen antiporter:
Sodium-hydrogen antiporter is a cell membrane cation exchanger that
catalyses the electroneural exchange of extracellular sodium ions for intracellular
hydrogen ions with a stociometry of 1:1. Molecular ionic studies have so far revealed
the presence of five subtypes of sodium hydrogen exchangers36
.
The most widely studied sodium isoform is referred to as NHE-1, is expressed
ubiquitously. The gene for NHE-1is located on short arm of chromosome 1; and
encodes a protein of B15 amino acid with two distinct domains.
Increased sodium-hydrogen antiport activity has been reported in leucocytes
of IDDM patients with nephropathy as well as patients with essential hypertension
and on red cells from IDDM patients with microalbuminuria. In serially passaged skin
fibroblasts, Trusian et al demonstrated significantly greater sodium hydrogen antiport
activity in cells from patients with nephropathy. These findings are consistent with the
view that cells of diabetic patients who develop nephropathy have intrinsic enhanced
capacity to proliferate and this phenomenon is associated with high rates of sodium
hydrogen exchange activity. The activity of sodium hydrogen antiport seems to act as
an indicator of some mechanism possibly genetically determined controlling cell
growth and hypertrophy on one hand and intracellular homeostasis on the other.
20
The environmental changes brought about by diabetes could lead to
dysregulation of these mechanisms in susceptible individuals and induces cell
hypertrophy and hyperplasia contributing to glomerular hypertrophy and mesangial
expansion in the kidneys as well as tubular hypertrophy and hyperplasia. Increased
renal sodium reabsorption would augment transmitted systemic and renal perfusion
pressure to maintain sodium balance. The increased perfusion pressure of the
glomerular capillaries is because of generalised vasodilatation present in diabetes.
This would lead to increased intra glomerular pressure, which determines at least in
part, and increase in GFR may be responsible for disruption of glomerular
permeability properties generating proteinuria.
On the other hand progressive mesangial expansion would lead to
glomerulosclerosis and further disruption of glomerular basement membrane
permeability selective properties. The insulin resistance associated with excessive
growth and the consequent hyperinsulinemia may cause lipid abnormalities, that in
the setting of vascular hyperpermeability characteristic of diabetic microvascular
disease, would further aggravate the renal histological damage and contribute in
combination with hypertension, and accelerated atherosclerosis of diabetic renal
failure37,38,39
.
PATHOLOGY
Gross Appearance:
The kidneys are of usually the normal size. They may be enlarged in the early
stages, but later becomes contracted with granular surface. The cut surface is usually
pale and the renal arteries may show arteriosclerosis in later stages.
21
Light microscopy:
Glomerular lesions:1,40,41,42
:
1. Nodular
2. Diffuse
3. Exudative
4. Glomerular hyalinization
Nodular lesions:
The nodular lesions described by Kimmelstiel and Wilson in 1936 have been
considered for a long time virtually specific for diabetes.
The nodules are well-demarcated hard masses, eosinophilic, and periodic acid
schiff positive, located in the central regions of peripheral lobules. When not
acellular, they contain pyknotic nuclei and infrequently foam cells can be seen
surrounding them. Relatively homogenous when stained with haematoxylin, their
structure is laminated when viewed in preparation with PAS or reticulin stains. They
are characteristically irregular in size and distribution, both within and between
glomerular loops and located away from the hilus. A rim of mesangial cells can
sometimes be seen between them and adjoining capillary, which is often distended.
Although when present, this lesion is pathognomonic for diabetes, it is not a
universal finding. Its incidence varies considerably from 12-46% in different series,
which included both IDDM and NIDDM cases. Nodules have been found in 55% of
an autopsy series of Pima Indian patients with NIDDM. Nodules are not seen in the
absence of diffuse lesions, and this reflects their appearance only after a long period
of disease.
22
Diffuse glomerular lesions:
Diffuse glomerular lesions comprise an increase in mesangial area and
capillary wall thickening with the mesangial matrix extending to involve the capillary
loops.
As the distribution of diffuse lesion is non-uniform, both among lobules of the
same glomerulus and between different glomeruli, leading to appearance suggestive
of transition to nodule formation. The thickening of capillary walls also tends to be
non-uniform, and this is particularly evident when the histological changes are not
very severe. The diffuse lesions represent earlier stage in the evolution of the disease.
In a large autopsy study, however changes compatible with diabetic
glomerulosclerosis were found in as many as 90% of patients with IDDM with
disease duration of more than 10 years. In patients with NIDDM, the reported
prevalence of these changes ranges between 25-51%.
Exudative Glomerular lesions:
Exudative lesions are highly eosinophilic rounded homogenous structures seen
in capsular space overlying a capillary loop (fibrin cap) or lying on the inside of
Bowman‟s capsule (capsular drop). They are non-specific, containing various proteins
and sometimes lipid materials.
Glomerular hyalinization:
As a consequence of above lesions, increasing number of glomeruli becomes
hyalinised in advanced cases. In some of the ischemic glomeruli, the tufts shrink with
fibrous thickening of the inner surface of Bowman‟s capsule.
23
Arterial lesions:
Diffuse intimal fibrosis in these vessels has been found to be more frequent
and advanced in autopsies on diabetics (Bell 1952,Warren et al 1966)
Arteriolar lesions:
Arteriolar lesions are prominent in diabetics with hyaline material
progressively replacing the entire wall structure. Bell first underlined that both
afferent and efferent arterioles could be affected. Bell also established lesions were
often present in absence of hypertension and the involvement of efferent vessel was
highly specific for diabetes. These arteriolar changes may be the first change
detectable by light microscopy in the diabetic kidney as judged by their recurrence at
2 years in non-diabetic kidneys transplanted into diabetic patients.
Tubular and interstitial changes:
Tubules and interstitium may show a variety of changes that are non-specific
and similar to those seen in other forms of progressive renal disease. Armani-Ebstein
lesions are the result of accumulation of glycogen in tubular cells of the
corticomedullary region in patients with profound glycosuria. More subtle tubular
changes consisting of vacuolization, a decrease in the intercellular spaces normally
present between the macula densa and a significant increase in the contact area
between them and extraglomerular mesangial cell43
.
Immunopathology:
Westberg and Michael confirmed previous observation of linear staining of
glomerular basement membrane for IgG, IgM, albumin and fibrinogen in kidneys of
24
patients with IDDM. The findings were later extended for IgG and albumin not only
in the glomerular basement membrane but also in the Bowman‟s capsule and
especially in the outer aspect of tubular basement membrane were considered specific
for diabetes.
Immunofluoroscence techniques have shown increased mesangial amounts of
type I, IV, V and VI collagens. Immunochemical analysis has also showed reduced
levels of laminin and markedly decreased amounts of heparan sulphates, proteoglycan
where as levels of fibronectin were normal in diabetic mesangium.
Electron microscopy:
Salient features are:
1) Thickening of glomerular basement membrane
2) Maintenance of fine detail of epithelial foot process and abundant epithelial
cytoplasm containing enlarged mitochondria.
3) Accumulation of basement membrane like material within the mesangium.
4) Fibrin deposition in the mesangium and along endothelial aspect of capillary
basement membrane.
Structure-function relationship:
In early phases of IDDM, the increase in luminal volume and filtration surface
area may explain the increase in GFR.
With advancing renal disease, a close association is observed between the
functional changes and mesangial expansion but not thickness of glomerular basement
membrane. Mesangial expansion also correlates inversely with capillary filtration
25
surface area, a variable closely associated with glomerular filtration rate from levels
of hyperfiltration to markedly reduce renal function. Therefore it has been suggested
that expansion of mesangium with attendant reduction in glomerular filtration surface
area that is responsible for the progressive loss of renal function in IDDM.
In IDDM patients, with low levels of microalbuminuria (i.e. AER of 20-
30mcg/min) no consistent glomerular abnormalities have been found. Above these
levels of urinary albumin excretion,the fractional volume of mesangium on average
increases significantly, and minor reduction in creatinine clearance and rise in blood
pressure are observed. Similar findings have been reported in NIDDM patients with
microalbuminuria and proteinuria42
.
INCIDENCE AND PREVALENCE OF MICROALBUMINURIA
The prevalence of microalbuminuria in IDDM patients has been reported in
range from 5-37% in different population based and diabetic clinic based studies. In
NIDDM patients, prevalence of microalbuminuria have been reported in between 8%
and 46% in Europeans and 47% in Pima Indians. Microalbuminuria is found not only
in patients with diabetes but also in patients with impaired glucose tolerance.
Age:
There is no correlation that has been found between AER and age
Sex:
There is male preponderance in IDDM patients. There is no correlation
between microalbuminuria and sex in NIDDM patients.
26
Duration of diabetes:
Prevalence increase with duration of IDDM with distinct variation in the rate
of increase. Incidence of microalbuminuria is very high during the first 3 years after
diagnosis of diabetes, declines at the end of first decade of diabetes and then increase
again to a peak around 12-15 years duration. The prevalence is 8% in patients with
IDDM of only 1-3 years of duration. The prevalence of microalbuminuria levels off
after 10 years (prevalence of 20%) and then assumes its steep climb of around 32%
after 30 years of post pubertal duration of diabetes.
Glycemia:
The level of glycemic control seems to be the strongest factor influencing
transition from normoalbuminuria to microalbuminuria. In recent observational study
of the dose response relationship between intensity of hyperglycemia (measured as
average glycosylated hemoglobin HbA1C level during a 2-4 year period) and the rise
to microalbuminuria was determined in a large cohort of IDDM patients.
A threshold effect of hyperglycemia on the development of microalbuminuria
was found. Below a HbA1c of 10.1%, the risk of persistent microalbuminuria varied
little. In contrast to above ,a threshold HbA1c of 10.1%, the risk of microalbuminuria
rose steeply with increasing levels of HbA1c. In comparison, the risk of
microalbuminuria increases six fold faster between HbA1c levels of 11 and 12% and
that between 8 and 9%. This relationship between HbA1c and levels of
microalbuminuria was independent of the effect of duration of IDDM.
27
Exercise:
Moderately strenuous exercise can provoke an exaggerated rise in AER in
patients with diabetes whose resting values are normal. The severity of exercise
induced albuminuria seems to be related to duration of diabetes and is modulated by
level of glucose control.
Blood pressure and heart rate:
Significant positive associations are found between microalbuminuria and
diastolic blood pressure and resting heart rate.
Other factors influencing the risk of developing microalbuminuria include
cigarette smoking, elevated levels of serum LDL cholesterol44,45
.
STAGES OF DIABETIC NEPHROPATHY
Diabetic nephropathy can conveniently be categorized into different stages,
which differ with respect to renal haemodynamic, systemic blood pressure, urinary
findings and susceptibility to therapeutic interventions.
28
Stages of diabetic nephropathy- typical findings44
Stage Glomerular
filtration
Albuminuri
a
Blood
Pressure
Years After
Diagnosis
Renal hyperfunction Elevated Absent Normal At
Diagnosis
Clinical latency High
Normal Absent Normal
At
Diagnosis
Microalbuminuria
(incipient nephropathy)
Within
normal
Range
20-
200mcg/min
(30-
300mg/day)
Rising within
or above
normal
5-15
Macroalbuminuria or
persisting proteinuria
(clinically manifest
nephropathy)
Decreasing
>200mcg/mi
n
(>300mg/day
)
Increased 10-15
End stage nephropathy Diminished Massive Increased 15-30
PROGNOSTIC SIGNIFICANCE OF MICROALBUMINURIA
Development of persistent proteinuria and overt nephropathy:
Prognostic significance of microalbuminuria for development of persistent
proteinuria and overt nephropathy has been demonstrated by five longitudinal cohort
studies of IDDM patients. These investigations have all suggested the existence of
threshold of AER above, which the risk of progression to clinical nephropathy
increases by about twenty fold. The overall findings of these studies are remarkably
similar, the differences in method of urine collection and length of follow up probably
being responsible for different risk levels of AER.
29
Table: Predictive value of albumin excretion rate (AER) for persistent clinical
proteinuria in patients with IDDM
Group No. of
subjects
Baseline
AER
mcg/min
Follow
up
Years
Type of
Collection
Predictive
value
Viberti et al45
63 >30 14 Over night 88%
Parving et al46
23 >28 6 24 hours 63%
Mathiesen et al47
71 >70 6 24 hours 100%
Mongensen &
Christensen et al48
43 >15 10 Short term 86%
Microalbuminuria is unlikely to be a marker for susceptibility to the
development of clinical nephropathy bur it is more likely to be a sign of early disease.
This interpretation has been recently corroborated by the finding that patients with
persistent microalbuminuria have more severe histological lesions than do patients
with normal AER.
Microalbuminuria and atherosclerotic diseases:
NIDDM is associated with two to three fold increased mortality mainly from
cardiovascular disease. This propensity for vascular disease among NIDDM patients
cannot be explained by co-existent conventional cardiovascular risk factors such as
hypertension or dyslipidemia since the effect of diabetes persists even after
controlling the confounding effects and other risk factors. Nor it can be entirely
attributed to hyperglycemic state, since the available data on the relationship between
glycaemic and cardiovascular complications in NIDDM if not conflicting, is certainly
inconclusive.
30
Mongensen in Denmark and Jarret et al in Britain were the first to explore the
role of microalbuminuria as a marker in patients with NIDDM. Both reported
independently in 1984 that microalbuminuria predicted all cause mortality chiefly
from cardiovascular diseases in NIDDM subjects. Three retrospective studies have
been examined to predict the prognostic significance of microalbuminuria in cohorts
of patients with NIDDM. Over an interval of 10-14 years, clinical proteinuria has
shown a significantly increased risk of death. They have also shown an increased risk
of cardiovascular death in these patients. Another prospective study of 3 years
duration has confirmed the greater incidence of cardiovascular events in patients with
NIDDM.
Lastly the association between microalbuminuria and cardiovascular risk
factor is not confined to diabetic individuals since it has recently been shown also to
extend to the general population45,46,47,48
.
METHODS OF MEASURING MICROALBUMINURIA
Small concentration of albumin in the urine can be measured qualitatively by
several methods.
Radioimmunoassay was the first and most widely used method. Various
methods to determine microalbuminuria are given in the table49.
31
Method sensitivity Time of assay
Single radio immune diffusion(mannil 1965) 1.25mg/ml 1 day
Electroimmuno assay (Laurel1966) 5mg/l 4-6hrs
Immunoturbidimetric assay (Teppor1982) 5mg/l 20-30min
Radio immuno assay (Keen and
Chlouvervakis, 1963)
6.2mcg/ml 1-2days
ELISA (Filding 1983) 250mcg/l 12-18min
Fluorescent immuno assay (Chavers 1984) 500mcg/l 4-6hrs
Latex agglutinates immuno nephelometry
(Vasquez 1984)
750mcg/l
6hrs
Immuno chemical semi quantitative dipstic
(MICRAL)
20-300mg/l 5sec-5min
In our study we have used Micral test for estimation of microalbuminuria.
Micral test (Boehringer Mannheim, Germany) is dipstick method of estimation of
microalbuminuria. Test principle is immunochemical in nature. Sensitivity of Micral
test was 93% ad its specificity was 93% when compared to radioimmunoassay in a
study by Gilbert PE et al50
. Micral test has also been compared with
immunoturbidimetricassay and radioimmunoassay methods. In all studies, Micral test
is comparable in sensitivity and specificity to the other methods of estimation of
microalbuminuria.
32
MICRAL TEST
Fig: 1 Micral II Test Strip
TREATMENT OF INCIPIENT NEPHROPATHY
Microalbuminuria indicates early stage of development of diabetic
nephropathy and also a marker of increased mortality from cardiovascular risk factors.
Microalbuminuria is also associated with other microvascular and macrovascular
complications of diabetes. It is a warning sign for the patient, which should not be
neglected. Progress of microalbuminuria to macroalbuminuria or overt nephropathy
can be reversed or delayed by intervention at this stage.
The strategies for treatment at this stage include1,5,7,8,51
:
1. Optimum glycemic control-diet, intensified insulin treatment, oral
hypoglycemic agents.
2. Blood pressure control and ACE inhibitors.
3. Dietary treatment.
4. Newer treatment modalities which are under study
Aldolase reductase inhibitors
Glycosaminoglycans
33
5. Correction of cardiovascular risk factors and other diabetic complications.
Stopping of cigarette smoking
Correction of dyslipidemia
Optimum glycemic control
In patients with IDDM with microalbuminuria, strict metabolic control by
continuous subcutaneous insulin infusion has been effective in reducing AER. Similar
reduction in AER is seen after multiple injection therapy, provided that similar levels
of blood glucose control are achieved, a finding suggesting that it is the attained
blood glucose control concentration rather than the modality of treatment that
matters52
.
Blood pressure control:
Blood pressure is generally above normal in microalbuminric stage of
nephropathy. In earlier studies multiple drug therapy of hypertension was used,
including β blockers, diuretics, vasodilators and calcium channel blockers. During last
few years, a angiotensin converting enzyme (ACE) inhibitors have shown great
promise not only in patients with established diabetic nephropathy but also in non
hypertensive patients with microalbuminuria. ACE inhibitors may be specifically
protective for renal function because of their ability to reduce efferent arteriolar
vasoconstriction and thus reduce the intra glomerular pressures. This “specific” effect
has been claimed to be separate from any effect on systemic blood pressure53
.
Antihypertensive treatment especially with ACE inhibitors therefore delays
the progression of established diabetic nephropathy and if started at the stage of
34
microalbuminuria may even prevent or at least retard the onset of clinically overt
renal disease54,55,56,57
.
Dietary and Behavioural modification:
Reductions of dietary protein by approximately 50% has been shown to reduce
the fractional clearance of albumin in patients with microalbuminuria, and to lower
GFR in patents with hyperfiltration, independently of changes in glucose control and
pressure. Diets restricted 0.5-0.6gm of protein /kg body weight per day is ideal and
does not have long-term detrimental effect on nutritional status of an individual51
.
Other treatment modalities:
Aldolase reductase inhibitors, which have been studied in a few studies, show
reduction in GFR and decrease in AER in IDDM patients who had either a normal
AER or microalbuminuria. But study in subjects with NIDDM with
microalbuminuria, it failed to show any effects on renal function. Further studies are
needed to confirm the finding.
Recent observation suggests that oral administration of sulodexide (a naturally
occurring glycosaminoglycan) extracted from pig intestinal mucosa, containing a fast
moving heparan like fraction (80%) and a dermatan sulphate fraction (20%) along
with ACE inhibitors seems to retard progression from incipient to overt
nephropathy in NIDDM patients. Mechanism is possibly by restoring glomerular
basement membrane charge and size selectivity to albumin molecules as well as
reducing glomerular capillary pressure. Further studies are needed to confirm this
finding58
.
35
Correlation of cardiovascular risk factors and other complications:
A detailed cardiovascular examination is necessary early in the course of
diabetic nephropathy. Hypertension must be treated energetically. Left ventricular
hypertrophy and function should be assessed echocardiographically at the stage of
microalbuminuria and thereafter every 6–12 months. Effective antihypertensive
therapy can reverse left ventricular hypertrophy. In addition, cardiac assessment
should include electrocardiography, stress testing, coronary angiography and Holter
monitoring is indicated whenever needed. Ischemic heart disease should be treated
aggressively. Peripheral vascular disease must be assessed and treated as necessary.
Doppler flow studies and arteriography may be useful to assess the severity of the
disease59,60
.
Microalbuminuria is frequently associated with hyperlipidemia and lipid
profile is an essential investigation and dyslipidemia should be treated61
.
Testing vibration perception threshold and thermal discrimination may
identify the risk of neuropathic ulceration. The test should be repeated regularly as
sensation may become impaired later, during the course of nephropathy. Autonomic
dysfunction is very common in nephropathic patients. The important manifestations
are postural hypotension and incomplete bladder emptying which predisposes to
urinary tract infection62
.
Microalbuminuria is frequently associated with retinopathy. Retinopathy
almost always accompanies diabetic nephropathy. Early and regular ophthalmic
review and prompt treatment is necessary to prevent blindness63,64
.
36
Diabetic retinopathy
Diabetic retinopathy is a well-characterized, sight-threatening, chronic
microvascular complication that eventually afflicts virtually all patients with diabetes
mellitus65
.
Diabetic retinopathy is characterized by gradually progressive alterations in
the retinal microvasculature,leading to areas of retinal non-perfusion,increased
vasopermeability, and pathologic intraocular proliferation of retinal vessels.
Epidemiology of diabetic retinopathy
All patients with type 1 diabetes and more than 60% of patients with type 2
diabetes develop some degree of retinopathy after 20 years. In patients with type 2
diabetes, approximately 20% have retinopathy at the time of diagnosis of diabetes and
most have some degree of retinopathy over subsequent decades. About 4% of patients
younger than 30 years of age at diagnosis and nearly 2% of patients older than 30
years of age at diagnosis were legally blind.Approximately 25% of patients with type
1 diabetes have retinopathy after 5 years, with this figure increasing to 60% and 80%
after 10 and 15 years, respectively66
.
Pathophysiology
The earliest histologic effects of diabetes mellitus in the eye include loss of
retinal vascular pericytes (supporting cells for retinal endothelial cells), thickening of
vascular endothelium basement membrane, and alterations in retinal blood flow. With
increasing loss of retinal pericytes, the retinal vessel wall develops outpouchings
(microaneurysms) and becomes fragile. With time, increasing sclerosis and
endothelial cell loss lead to narrowing of the retinal vessels, which decreases vascular
37
perfusion and may ultimately lead to obliteration of the capillaries and small vessels,
the resulting retinal ischemia is a potent inducer of angiogenic growth factors. These
factors promote the development of new vessel growth and retinal vascular
permeability. Proliferating new vessels in diabetic retinopathy have a tendency to
bleed, which results in preretinal and vitreous hemorrhages and later macular edema.
Risk factors
1. Duration of diabetes is closely associated with onset and severity of diabetic
Retinopathy.
2. Lack of glycemic control.
3. Renal disease, as manifested by microalbuminuria and Protienuria67
.
4. Hypertension68
.
5. Elevated serum lipid levels are associated with extravasated lipid in the retina
(hard exudates) and visual loss69
.
Clinical findings
Clinical findings associated with early and progressing diabetic retinopathy
include haemorrhages or microaneurysms (H/Ma), cotton-wool spots (CWSs), hard
exudates, intraretinal microvascular abnormalities (IRMAs), and venous calibre
abnormalities (VCABs), such as venous loops, venous tortuosity, and venous beading.
The intraretinal hemorrhages can be “flame-shaped” or “dot/blot” like in
appearance. IRMAs are either new vessel growth within the retinal tissue itself or
shunt vessels through areas of poor vascular perfusion. It is common for IRMAs to be
adjacent to CWSs, which are caused by micro infarcts in the nerve fiber layer.
VCABs are a sign of severe retinal hypoxia. In some cases of extensive vascular loss,
38
however, the retina may actually appear free of non-proliferative lesions. Such areas
are termed “featureless retina” and are a sign of severe retinal hypoxia.
Symptoms of diabetic retinopathy
1. Patient complaints of blurred vision, usually central vision and
metamorphosia as a result of maculopathy with foveal involvement.
2. Black spots, floaters or sudden visual loss may be experienced by patients
with vitreous haemorrhage, depending on quantum of bleed.
Kanski classification of diabetic retinopathy70
1. Background diabetic retinopathy
a. Haemorrhages (Dot and Blot)
b. Microaneurysms (Located in inner nuclear layer)
c. Hard exudates ( Located in between inner plexiform and inner nuclear
layer)
d. Retinal edema (Located between outer plexiform and inner nuclear
layer)
2. Pre proliferative
a. Vascular changes(beading , looping)
b. Dark blot haemorrhages
c. Cottonwool spots
d. Intraretinal microvascular abnormalities
e. Shunt vessels
3. Proliferative
a. Neo vascularisation
39
b. Fibrous proliferation
c. Vitreous detachment and haemorrhages
4. Maculopathy
a. Focal
b. Diffuse
c. Ischaemic
Classification of diabetic maculopathy
Intraretinal
Macular edema
Macular hard exudates
Macular ischaemia
Pre retinal and vitreo- retinal
Thick and post hyaloids
Thick and pre retinal membrane
Tractional detachment of macula
Macular ectodia
Monitoring and treatment of diabetic retinopathy
Appropriate clinical management of diabetic retinopathy has been defined by
results of four major, randomized, multicentered clinical trials the Diabetic
Retinopathy Study (DRS), the ETDRS, the Diabetic Retinopathy Vitrectomy Study
(DRVS) and the DCCT.
40
Figure 2: Background diabetic retinopathy showing scattered exudates and
haemorrhages near fovea. Normal vision (6/6). Laser photocoagulation indicated
Figure 3: Background diabetic retinopathy with severe maculopathy. Hard
exudates at macula. Vision 6/60. Central vision permanently lost.
41
Figure 4: Proliferative diabetic retinopathy with disc neovascularization. Vision
6/6 Laser photocoagulation required
Figure 5: Advanced proliferative diabetic retinopathy with traction retinal
detachment resulting from preretinal scar tissue. Vision: Hand movement. Too
late for treatment
42
Figure 6: Proliferative diabetic retinopathy with abnormal vessels at optic disc
and retina with early vitreous haemorrhage. Eye in danger of being blind and
requires laser photocoagulation
43
METHODOLOGY
One hundred patients of diabetes (NIDDM) who are eligible and attending
outpatient department and admitted in medical wards of Navodaya medical college
hospital and research centre were chosen for the study based on random selection.
Patients were considered to be diabetic based on WHO criteria for diagnosis of
diabetes mellitus which is: -
1. Symptoms of diabetes mellitus plus a random glucose concentration >200
(11.1mmol/l). The classical symptoms of diabetes mellitus include polyuria,
polydipsia ,polyphagia and unexplained weight loss
OR
2. Fasting blood glucose >126 mg/dl (7.0mmol/l). Fasting is defined as no
caloric intake for at least 8 hours.
OR
3. 2 hour plasma glucose > 200mg/dl (11.1 mmol/l) during an oral glucose
tolerance test. Among diabetics, the above criteria were considered to include
the patients for the study.
Selection criteria
Inclusion criteria
1. The American Diabetic Association criteria for the diagnosis of Type 2
diabetes mellitus are FPG > 126 mg/dl with symptoms of diabetes and PPPG >
200 mg/dl on two different occasions.
44
OR
Two hour plasma glucose > 200 mg/dl during an oral glucose tolerance test.
2. Diagnosis of DM after 30 years of age.
Exclusion criteria
1) Patients with macroalbuminuria
2) Patients with congestive cardiac failure, urinary tract infection.
3) Ketonuria
4) Pregnant patients
5) Patients with overt diabetic nephropathy
6) Serum creatinine > 1.5 mg/dl
7) Diabetes with any acute stressors like infections, MI, etc.,
8) Diabetes with prior hypertension or within 5years of detection of type 2
diabetes mellitus.
The selected patients were studied in detail with history and physical
examination
History
Patient‟s characteristics like age, sex, age of onset and duration of diabetes.
All details regarding the presenting complaints were noted.
Total duration of diabetes, the drugs the patient was taking and the dosages
were noted. The regularity of the treatment taken by the patients was also
noted. The family history regarding diabetes was taken.
45
Personal history regarding smoking, alcohol consumption, bowel and bladder
habits and drug intake were noted.
A complete clinical examination was carried out in each patient. Height and
weight were measured in all cases and body mass index (BMI) was calculated by
weight in kg / height in m2.
The following investigations were done in all the patients.
Microalbuminuria was estimated by Micral test in all the cases.
Fasting Blood sugar and Postprandial blood sugar
Glycosylated hemoglobin
Blood urea and serum creatinine
Fasting lipid profile
Urine routine and culture
Electrocardiogram
Ultrasonography of the abdomen, echocardiogram and chest x-ray were done in
selected cases only.
Estimation of Microalbuminuria by Micral test:
All patients having overt macroalbuminuria detected by albustik were
excluded from study. Micral test, a immunological rapid dip stick semi qualitative
technique for detection of microalbuminuria, was used for estimation of
microalbuminuria.
46
Micral test components:
1 test strip contains monoclonal antibodies against human albumin
(immunoglobulin G) labelled with colloid gold 2.2mg, fixed albumin 7.7 mg
Test principle
There is a serial arrangement of several reagent pads, which are in fluid
communication by a reaction controlling chromatographic process. This step
combines one step handling with a complex chemistry. The single reaction steps are
as follows:
Urine of the sample is transported through the wick fleece to the buffer fleece,
where acidic urine is adjusted to proper pH
Upon entering the conjugate fleece, the antigen – antibody reaction takes
place. Albumin of the sample is specifically bound to a soluble conjugate of
antibodies and marker enzyme resulting in an antigen – conjugate complex
The excess antibodies are bound to immobilized albumin on the capture
matrix and removed from the sample in this way.
Only the complex of conjugate with sample-albumin reaches the substrate pad.
Here the colour reaction takes place, the marker enzyme B-Galactosidase
cleaves off the purple dye chlorophenol red from the Yellow substrate
(chlorophenol red galactoside) in a kinetic reaction. The intensity of the colour
produced is proportional to the albumin concentration in the urine.
47
Method of data collection:
All patients were afebrile during the course of collection of urine and were
kept at rest during the collection of urine. Urine of the patient was first tested for
albumin by albustik method. Patients who were negative for albumin by the albustik
method were only included in this study.
First morning mid stream urine sample that was collected in a sterile container
was used for determining microalbuminuria. Test strip was immersed in urine such
that fluid level was between the two black bars provided on the strips. Strip was
withdrawn after 5 seconds. Strip was placed horizontally across the urine vessel and
colour change in the test zone was compared with colour scale after one minute.
Sensitivity of the kit is 0.4ng/ml and measuring range is 0.8 to 10ng/ml.
Occular examination:
Detail ophthalmic examination including visual acuity and slit lamp
examination was done for all patients. Fundus examination under mydriasis with
tropicamide + phenylephrine eye drops was done for all patients for the presence of
retinopathy.
Fundus photography and fluorescein angiography was performed in indicated
patients.
48
RESULTS
Table 1 shows the age and sex distribution of patients
Table1: Age and sex distribution
Age in yrs
Male Female Total
No % No % No
40-50 23 40.26 16 37.21 39
51-60 15 26.32 16 37.21 31
61-70 14 24.56 6 13.95 20
>70 5 8.77 5 11.63 10
Total 57 100 43 100 100
Mean age±SD 54.82±12.38 54.82±11.08 54.87±11.59
P value Mean age between male and female=0.965
39 patients were in the age group between 40-50 years, among whom 23 were
male,16 were female patients. 31 patients were in the age group between 51 and 60
years, among whom 15 were male and 16 were female patients. 20 patients were in
the age group between 61 and 70 years, among whom 14 were male and 6 were
female patients. 10 patients were in the age group greater than 70 years, among whom
5 were male and 5 were female patients. The mean age of male patients in the study
was 54.82 ± 12.38 years and that of the female patients was 54.82 ±11.08 years. The
mean age of detection of diabetes mellitus among the male patients was 48.84± 10.11
years and in the patients was 48.75 ± 8.68 years.
The mean age between male and female is not statistically significant with
p=0.964.
49
Graph – 1: Graph showing age and sex distribution of patients
39 patients were in the age group between 40-50 years, among whom 23 were
male(40.26%),16 were female patients(37.21%). 31 patients were in the age group
between 51 and 60 years, among whom 15 were male(26.32%) and 16 were female
patients(37.21%). 20 patients were in the age group between 61 and 70 years, among
whom 14 were male(24.56%) and 6 were female patients(13.95%). 10 patients were
in the age group greater than 70 years, among whom 5 were male(8.77%) and 5 were
female patients(11.63%).
50
Table 2: Number of patients with microalbuminuria and retinopathy
Microalbuminuria Retinopathy
- + - +
62 38 56 44
There were 62 patients negative for microalbuminuria.38 patients were positive
for microalbuminuria. There were 56 patients negative for retinopathy, 44 patients
were positive for retinopathy.
Graph – 2 : Pie diagram showing percentage of patients with microalbuminuria
and retinopathy
51
Table - 3:Association of age with microalbuminuria and retinopathy
Age in
years
Number of
patients
Microalbuminuria Retinopathy
- + - +
40-50 39 31 8 29 10
51-60 31 20 11 19 12
61-70 20 10 10 8 12
>70 10 1 9 - 10
Among 39 patients in the age group between 40-50 years,8 patients had
microalbuminuria and 10 patients had retinopathy.31 patients were in age group
between 51-60 years, among them 11 patients had microalbuminuria and 12 patients
had retinopathy.20 patients were in the age group between 61 -70 years, among whom
10 patients had microalbuminuria and 12 patients had retinopathy.10 patients were in
the age group of above 70 years , among whom 9 patients had microalbuminuria and
all 10 were positive for retinopathy.
Incidence of microalbuminuria is more likely for the age group above 50 years of age
as compared to the age group <50 years of age with p=0.053.
Incidence of retinopathy is more likely for the age group above 50 years of age as
compared to the age group <50 years of age with p=0.001.
52
Graph – 3 : Association of age with microalbuminuria and retinopathy
0
20
40
60
80
100
120
_ + _ +
Pe
rce
nta
ge o
f p
atie
nts
microalbuminuria retinopathy
41-50
51-60
61-70
>70
Among 39 patients in the age group between 40-50 years,8 patients had
microalbuminuria (20.5%)and 10 patients had retinopathy(25.64%).31 patients were
in age group between 51-60 years, among them 11 patients had
microalbuminuria(35.48%) and 12 patients had retinopathy(38.70%).20 patients were
in the age group between 61 -70 years, among whom 10 patients had
microalbuminuria (50%)and 12 patients had retinopathy(60%).10 patients were in the
in the age group of above 70 years , among whom 9 patients had
microalbuminuria(90%) and all 10 patients(100%) had retinopathy
53
Table 4 :Association of Duration of diabetes mellitus with microalbuminuria
and retinopathy
Duration of
diabetes
mellitus
Number of
patients
Microalbuminuria Retinopathy
- + - +
< 5 39 31 8 29 10
6-10 31 20 11 19 12
11-15 20 10 10 8 12
16-20 10 1 9 - 10
Among 39 patients with duration of diabetes <5years ,8 patients had
microalbuminuria and 10 patients had retinopathy.Among 31 patients with duration of
diabetes between 6-10 years, 11 patients had microalbuminuria and 12 patients had
retinopathy.Among 20 patients with duration of diabetes between 11-15years, 10
patients had microalbuminuria and 12 patients had retinopathy.Among 10 patients
with duration of diabetes between 16-20 years , 9 patients had microalbuminuria and
all 10 were positive for retinopathy.
Incidence of microalbuminuria is more likely with duration of diabetes above 6 years
as compared to the duration of diabetes below 6 years.age.
Incidence of retinopathy is more likely with duration of diabetes above 6 years as
compared to the duration of diabetes below 6 years.age.
Graph – 4 : Association of Duration of diabetes mellitus with microalbuminuria and
retinopathy
Among 39 patients with duration of diabetes <5years,8 patients had microalbuminuria
(20.5%)and 10 patients had retinopathy(25.64%).31 patients with duration of diabetes
between 6-10 years, among them 11 patients had microalbuminuria(35.48%) and 12 patients
had retinopathy(38.70%).20 patients with duration of diabetes between 11-15 years, among
whom 10 patients had microalbuminuria (50%)and 12 patients had retinopathy(60%).10
patients with duration of diabetes above 16 years, among whom 9 patients had
microalbuminuria(90%) and all 10 patients(100%) had retinopathy
54
0
20
40
60
80
100
120
_ + _ +
Pe
rce
nta
ge o
f p
atie
nts
microalbuminuria retinopathy
≤5
06-1 0
1 1-15
16-20
55
Table 5:Association of HbA1c with microalbuminuria and retinopathy
HbA1c No of
patients
Microalbuminuria Retinopathy
- + - +
<6.5 22 16 6 18 4
6.5-7 22 17 5 18 4
7-7.5 16 12 4 8 8
>7.5 40 17 23 12 28
22 patients had HbA1c values less than 6.5% among them 6 were positive for
microalbuminuria and 4 were positive for Retinopathy. 22 patients had HbA1c
between 6.5% and 7%among them 5 were positive for microalbuminuria and 4 were
positive for retinopathy.
16 patients had HbA1c levels between 7.0% and 7.5% among them 4 were
positive for microalbuminuria and 8 were positive for retinopathy.40 patients had
HbA1c values more than 7.5%,among them 23 were positive for microalbuminuria
and 28 were positive for retinopathy.
The association of microalbuminuria and retinopathy with HbA1c is significant with
P values 0.016 and 0.001 respectively
56
Graph - 5:Association of HbA1c with microalbuminuria and retinopathy
22 patients had HbA1c values less than 6.5% among them 6 were positive for
microalbuminuria(27.27%) and 4 were positive for Retinopathy(18.18%). 22 patients
had HbA1c between 6.5% and 7%among them 5 were positive for microalbuminuria
(22.72%)and 4 were positive for retinopathy(18.18%).
16 patients had HbA1c levels between 7.0% and 7.5% among them 4 were
positive for microalbuminuria(25%) and 8 were positive for retinopathy(50%).40
patients had HbA1c values more than 7.5%,among them 23 were positive for
microalbuminuria(57.5%) and 28 were positive for retinopathy(70%).
0
10
20
30
40
50
60
70
80
90
_ + _ +
per
cen
tage
of p
atie
nts
Microalbuminuria Retinopathy
HbA1c
<6.5
6.5-7
7-7.5
>7.5
57
Table:6 Association of BMI with microalbuminuria and retinopathy
Body mass
index(kg/m2)
Number of
patients
Microalbuminuria Retinopathy
- + - +
<25 78 53 25 49 29
>25 22 9 13 7 15
78 patients had a BMI less than 25kg/m2, out of them 25 patients were positive for
microalbuminuria and 29 patients were positive for retinopathy.
22 patients had a BMI above 25 kg/m2, out of them 13were positive for
microalbuminuria and 15 were positive for retinopathy
The association of microalbuminuria and retinopathy with BMI is significant with P
values 0.02 and 0.01 respectively
58
Graph -6 :Showing Association of BMI with microalbuminuria and retinopathy:
78 patients had a BMI less than 25kg/m2, out of them 25 patients were positive for
microalbuminuria(32.05%) and 29 patients were positive for retinopathy(37.17%).
22 patients had a BMI above 25 kg/m2, out of them 13were positive for
microalbuminuria (59.09%)and 15 were positive for retinopathy(68.18%).
0
10
20
30
40
50
60
70
80
microalbuminuria - microalbuminuria+ retinopathy- retinopathy+
p
e
r
c
e
n
t
a
g
e
s
<25
>25
59
Table.7: Association between microalbuminuria and retinopathy
Microalbuminuria + Microalbuminuria -
Retinopathy + 31 13
Retinopathy - 7 49
31 subjects had evidence of both microalbuminuria and retinopathy,13 patients had
retinopathy without microalbuminuria,7 patients had only microalbuminuria without
retinopathy
The association between microalbuminuria and diabetic retinopathy is significant with
P value of <0.001.
Graph-7: Association between microalbuminuria and retinopathy
31 subjects had evidence of both microalbuminuria and retinopathy,13 patients had
retinopathy without microalbuminuria,7 patients had only microalbuminuria without
retinopathy
0
10
20
30
40
50
Microalbuminuria + Microalbuminuria -
Association between microalbuminuria and retinopathy Retinopathy + Retinopathy -
60
DISCUSSION
The prevalence of microalbuminuria:
In the present study the prevalence of microalbuminuria is 38%.
Similar results were shown in the following studies,
In a study conducted by Unnikrishnan RI et al in Chennai, South India, the prevalence
of microalbuminuria is 27%.71
Gupta et al reported a prevalence of 26.6% in 65 type 2 north Indian patients.72
John et al reported a prevalence of 19.7% from a tertiary hospital in Vellore, south
India.73
S.No Year Investigator Location Prevalence
1 1991 John et al
Vellore 19.7%
2 1991 Gupta et al North India 26.6%
3 2007 Unnikrishnan et al Chennai 27%
4 2010 Present study Raichur 38%
Various epidemiological studies have reported marked variation in the
prevalence of microalbuminuria ranging from 7%to 42 %.The prevalence in our study
is within this range.
The prevalence of retinopathy:
The prevalence of retinopathy in our study is 44%.Various studies on the
prevalence of diabetic retinopathy in India are as follows:
61
S. No Year Investigator Location Prevalence
1 1996 Rema et al 74
Chennai 34.1%
2 1999 Dandona et al 75
Hyderabad 22.6%
3 1999 Ramachandran et al76
Chennai 23.7%
4 2002 Narendran et al77
Palakkad 26.8%
Age distribution of microalbuminuria:
In our study among 39 patients in the age group between 40-50 years, 8(20.5)
patients had microalbuminuria.31 patients were in age group between 51-60 years,
among them 11(35.4%) patients had microalbuminuria.20 patients were in the age
group between 61 -70 years, among whom 10(50%) patients had microalbuminuria
and 10 patients were in the in the age group of above 70 years , among whom 9(90%)
patients had microalbuminuria.
The prevalence of microalbuminuia increases with that of the age of the
patients. The increasing age was reported as one of the risk factors for the
development of microalbuminuria in various studies conducted by John et al, Vijay et
al, Klein R et al in the Wisconsin study and Nelson et al in Pima Indians78,79,80
.
Deterioration in the beta cell function, which occurs parripassu with increasing
age, is likely to contribute to worsening glycaemic control.
Association of duration of diabetes with microalbuminuria and retinopathy:
In our study, it has been observed that longer the duration of diabetes the
higher the prevalence of microalbuminuria and retinopathy. In patients with diabetes
62
for less than 5 year duration , 20.5% had microalbuminuria and 25.6% had
retinopathy. In patients with diabetes for more than 15 years, 90% had
microalbuminuria and 100% had retinopathy.Similar findings were observed in a
study conducted by Varghese et al in which 30.4% patients with diabetes for less than
5 year duration had microalbuminuria and 96% patients with diabetes for more than
than 15 year duration had microalbuminuria.81
Chronic hyperglycemia is thought to be the primary cause of diabetic
retinopathy. Evidence in support for this hypothesis has come from the Diabetes
Control and Complications Trial (DCCT), which found that intensive insulin therapy,
achieving a mean hemoglobin A1C (A1C) of 7.9 percent, reduced the incidence of
new cases of retinopathy by as much as 76 percent compared with conventional
therapy. The reduction was directly related to the degree of glycemic control as
estimated from haemoglobin A1C values (mean A1C with conventional therapy was
approximately 9.9 percent); progressive retinopathy was uncommon in patients with
A1C values below seven percent.82
Association between microalbuminuria and diabetic retinopathy :
Our study showed that in addition to HbA1c, BMI and the duration of illness,
microalbuminuria is a contributing factor in the degree of retinopathy (p < 0.001) and
the association between microalbuminuria and diabetic retinopathy observed in the
present study could be explained by the view that microalbuminuria might represent a
state of generalized vascular dysfunction [Deckert et al]. Enzymes involved in the
metabolism of anionic components of the extracellular matrix (e.g. heparan sulphate
proteoglycan) vulnerable to hyperglycemia, seem to constitute the primary cause of
albuminuria and its associated complications.83
63
Estacio RO et al evaluated the correlation between albuminuria and
retinopathy in 815 patients with type 2 diabetes (144 Hispanics and 671 whites]. The
presence of albuminuria, defined as urinary albumin excretion >200 mcg/min, was a
significant predictor for retinopathy (as detected via stereoscopic retinal fundus
photographs) among the Hispanic (odds ratio 11.1). 84
Similar association observed in
studies conducted by Lunetta et al, Manaviat et al.85,86
Association of HbA1c with microalbuminuria and retinopathy:
In our study, only 11 out of 44 patients who had a normal HbA1c (< 7.0%)
manifested microalbuminuria, whereas with HbA1c values more than 7, 27 out of 56
(nearly 50%) had microalbuminuria. Also nearly 64% (36/56) patients with Hb A1c
>7 had evidence of retinopathy. It is seen from the above result that even small
increments of HbA1cmore than 7.0% result in almost doubling of the incidence of
microalbuminuria and retinopathy.
Poor glycemic control as a risk factor for microalbuminuria was reported in
various studies including UKPDS, DCCT trial and a study conducted by
Unnikrishnan et al.71,82,87
The mechanism by which lack of glycemic control predisposes to vascular
disease is incompletely understood. Two proposed contributing factors are advanced
glycosylation end products and sorbitol; protein kinase C and other factors also may
contribute.
In addition to systemic factors, organ-specific factors also appear to be
important. In the kidney, for example, stimulation of mesangial matrix production by
64
hyperglycemia, and activation of protein kinase Cmay contribute to the glomerular
injury.88,89
.
Association of BMI with microalbuminuria and retinopathy:
This study has also brought out a significant association of microalbuminuria
with body mass index of more than 25kg/m2. Of the 22 patients with BMI of more
than 25, 13had microalbuminuria (52%). 15 out of 22 (68%) patients with BMI > 25
had retinopathy . Similar findings have been brought forth by Patel Kl et al 90
, Taneja
V et al 91
, Jadhav UM et al 92
.
The possible explanation for this could be
Increasing body mass index is a reflection of insulin resistance which in turn leads
to endothelial dysfunction and microalbuminuria.
Poor glycemic control which in turn is an outcome of insulin resistance is also
held responsible.
Study limitations
It was done in a small group it may not represent the entire population.
65
CONCLUSION
The present study has shown that there is significant association between the
presence of microalbuminuria and retinopathy.
It has also shown that there is increase in the prevalence of microalbuminuria
and retinopathy with increasing age, HbA1c >7%,BMI>25 Kg/m2.
66
SUMMARY
Out of 100 cases,57 cases were male and 43 cases were female.
Microalbuminuria was found in 38 % of patients and diabetic retinopathy was
present in 44 % of patients..
Microalbuminuria and retinopathy show a direct relationship with increasing
age of patients, HbA1c levels and BMI.
HbA1c value above 7 % is associated with increasing incidence of
microalbuminuria and retinopathy.
Patients with a BMI of more than 25 kg/m2
have significant increase in the
incidence of microalbuminuria and retinopathy.
Microalbuminuria and diabetic retinopathy were present together in 31% of
patients showing that there is a significant association between them.
67
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81
ANNEXURE - I
INFORMED CONSENT
ASSOCIATION BETWEEN MICROALBUMINURIA AND DIABETIC
RETINOPATHY IN TYPE 2 DIABETES PATIENTS – A ONE YEAR CROSS-
SECTIONAL STUDY
Consent: I, ................................. willingly and in my full give sense, give my consent
to take part in this study. The risk and benefits of which have been explained to me in
my own vernacular language.
Witness
Date Signature of the
patient/ relative
82
ANNEXURE – II
PROFORMA
Name: IP/OP No:
Age: Date of admission:
Sex: Date of discharge:
Religion: Marital status:
Address:
Occupation:
Education: Signature of the Patient
Income group: High/middle/poor
CHIEF COMPLAINTS:
Polyuria Polydipsia Blurring of vision
Weight loss Tiredness Polyphagia
Pruritus Aches and pains Skin infections
HISTORY OF PRESENTING ILLNESS
1) Cardiovascular symptoms:
Angina myocardial infarction exertional dyspnea orthopnea
PND palpitations syncope sweating
83
Swelling of feet
2) Peripheral vascular symptoms:
Intermittent claudication Gangrene Impotence thrombophlebitis
3) Cerebrovascular symptoms:
Giddiness headache vomiting transient ischemic attacks Stroke
4) Visual symptoms:
Blurring of vision Progressive loss of vision sudden loss of vision
5) Renal symptoms:
a) Symptoms of urinary tract infection:
Dysuria Fever with chills Flank pain
b) Symptoms of nephropathy:
Swelling of feet Puffiness of face Distension of abdomen
Increasing sensitivity of insulin
6) Symptoms of neurological complications:
a) Symptoms of polyneuropathy:
Tingling Numbness Paraesthesia Nocturnal pain
Sensory ataxia Trophic ulcers Charcot joints
b) Symptoms of mononeuropathy:
Wrist drop Foot drop
c) Cranial nerves:
Diplopia Squint Deviation of the angle of mouth
Inability to close the eyes
d) Symptoms of radiculopathy:
e) Symptoms of autonomic neuropathy
Dysphagia vomiting Nocturnal diarrhea Syncope
84
f) Symptoms of amyotrophy:
Paraesthesia of the anterior thigh Thinning of proximal muscle
Weakness of proximal muscles
7) Symptoms of Diabetic skin complications:
Recurrent skin infections Abscesses Carbuncles
8) Gastro intestinal symptoms:
Dysphagia Abdominal pain Nausea/Vomiting Diarrhea
Weight loss Loss of appetite
9) Genito urinary symptoms:
Polyuria/Nocturia Balanoprosthitis Impotence Dysuria
Discharge per urethra Discharge per vagina
DIABETES HISTORY
Diabetes diagnosed in the year:
Duration of Diabetes:
Diabetes onset at the age of:
Mode of onset of Diabetes:
Family history of Diabetes:
Drugs used for Diabetes: OHA / INSULIN/ INSULIN + OHA
PAST HISTORY
History of hypertension
History of Angina / Myocardial infarction
History of Transient ischemic attack / stroke
PERSONAL HISTORY
HABITS YES NO STOPPED
Smoking
85
Sweets
Alcohol
Tobacco
Appetite /bowel /bladder
FAMILY HISTORY
MEMBERS PRESENT ABSENT
Father
Mother
Sisters
Sons
Daughters
Spouse
Others: History of Hypertension, Ischemic heart disease , Cerebro vascular
accidents
Obesity and Sudden death
OBSTETRIC AND GYNAECOLOGICAL HISTORY
Menarche/ Menopause
Gravida/Para
Abortion
History of stillbirths
History of delivery of large babies
GENERAL PHYSICAL EXAMINATION
1) BUILT: Well / moderately /poor/ emaciated
2) WEIGHT:
HEIGHT:
86
BODY MASS INDEX:
3) PULSE:
4) BLOOD PRESSURE:
5) PALLOR:
EDEMA, PEDAL:
CLUBBING/KOILONYCHIA
CYANOSIS:
ICTERUS:
LYMPHADENOPATHY:
6) JUGULAR VENOUS PULSE
7) PERIPHERAL PULSE
8) SKIN CHANGES:
Diabetic dermopathy
Acanthosis nigricans
Scleroderma
Xanthoma
Fungal infection
Skin tags
9) EYES:
Normal/ Xanthoma / Arcus / Cataract
10) FUNDUS
SYSTEMIC EXAMINATION
1) CARDIOVASCULAR SYSTEM
INSPECTION
PALPATION
87
PERCUSSION
AUSCULTATION
OTHER FINDINGs
2) RESPIRATORY SYSTEM
INSPECTION
PALPATION
PERCUSSION
AUSCULTATION
OTHER FINDINGS
3) ABDOMEN
INSPECTION
PALPATION
PERCUSSION
AUSCULTATION
OTHER FINDINGS
4) CENTRAL NERVOUS SYSTEM
HIGHER MENTAL FUNCTIONS
CRANIAL NERVES
MOTOR SYSTEM
NUTRITION
TONE
POWER/REFLEXES
CO-ORDINATION
INVOLUNTARY MOVEMENTS
88
SENSORY SYSTEM
TOUCH / PAIN / TEMPERATURE/VIBRATION /
POSITION SENSE /
DIABETIC RETINOPATHY: PRESENT/ ABSENT
INVESTIGATIONS
1) URINE:
Macroalbuminuria
Microalbuminuria
Sugar
Microscopy
Ketone bodies
2) BLOOD:
Fasting blood glucose
Post prandial blood glucose
Glycosylated hemoglobin:
Blood urea:
Serum creatinine:
Lipid profile
1. Total cholesterol
2. Triglycerides
3. HDL
4. LDL
3) ELECTROCARDIOGRAM
4) ECHOCARDIOGRAM (selected cases only)
5) ABDOMINAL ULTRASONOGRAPHY
89
DIAGNOSIS
TREATMENT GIVEN:
1) Diet
2) Diet + OHA
3) Diet + OHA + insulin
4) Diet + insulin
Signature of Candidate
Signature of Co-guide Signature of Guide
90
ANNEXURE - III
Master chart
HbA1cFBS PPBS B/U
Sr.Cre RP Htn BMIS.No
Name IP/OP No
Age
Sex Micro Duration of DMAlb
1 Hanumanthaya 14494 65 M + 20.1 270 355 36 1 + - 10.1 12years2 Venkanna 10957 74 M + 16.4 221 291 22 0.9 + - 9.8 16years3 Shankarappa 12888 60 M - 17.8 173 212 38 0.8 + - 7.8 13years4 Chandrasekhar 4326 56 M - 22.5 164 250 33 1.2 - - 6.8 7years5 Padmavathi 12782 50 F - 18.2 160 280 24 1.2 - - 7.6 4years6 Baburao 13618 64 M + 26.3 201 294 26 1.4 + - 9.3 12years7 Kamalamma 23320 54 F + 30.1 230 289 27 1 + - 10.2 8years8 Gouramma 29070 43 F - 18.4 214 261 25 0.8 - - 6.9 5years9 Balappa 13729 47 M - 22.5 210 280 22 0.8 - - 6.8 5years10 Veerabhadrappa 3952 40 M - 26.3 170 250 34 1.1 + - 7.2 5years11 Hussain bee 137690 70 F + 22.6 190 286 26 0.9 + - 8.1 12years12 Veeranagouda 5710 48 M - 29.7 185 270 38 1.3 + - 8.4 5years13 Nagappa 12343 60 M + 21.9 170 250 34 1.2 + - 7.8 8years14 Abdul mohd 27092 65 M + 24.3 210 290 29 1.1 + - 8.4 11years15 Sharanappa 14466 60 M - 23 165 260 30 1.2 - - 7.6 6years16 Shashaidevi 29718 41 F - 28.3 192 280 24 1.1 - - 9.2 5years17 Thayanna 5353 45 M - 21.8 160 247 29 1.2 - - 6.8 5years18 Laxmanna 27221 45 M - 26.2 180 240 24 0.9 - - 7 4years19 Veerabadrappa 12938 55 M + 26.3 180 212 34 1.1 - - 6.6 7years
HbA1cFBS PPBS B/U
Sr.Cre RP Htn BMIS.No
Name IP/OP No
Age
Sex
Micro Duration of DMAlb
HbA1cFBS PPBS B/U
Sr.Cre RP Htn BMIS.No
Name IP/OP No
Age
Sex
20 Thippaya 28561 63 M + 19.8 189 232 23 1 + - 6.8 13years21 Radhamma 182273 60 F - 22.6 180 256 24 1.1 - - 7.1 6years22 Khaja bee 19650 60 F + 22.9 196 272 28 0.9 - - 8.1 6years23 Khaja moinuddi 21462 48 M - 20.3 154 230 20 0.8 - - 6.4 5years24 Shivamma 19630 42 F - 21.9 146 212 28 0.9 - - 6.3 4years25 Bheemavva 19411 48 F - 22 149 219 29 1 - - 6.4 4years26 Laxmi devi 3823 75 F + 18.2 214 356 29 1.2 + - 10.2 17years27 Bhemmayya 19363 62 M - 22.6 241 317 34 1.3 + - 9.5 12years28 Khaja bee 19650 65 F - 30.1 200 290 42 0.9 - - 7.8 11years29 Ismail 19412 53 M - 24.2 210 290 26 1.1 - - 7.4 6years30 Basavaraj 32752 50 M + 23.3 140 195 29 1 - - 6.1 5years31 Virupakshappa 30710 62 M - 23 156 240 20 1.1 - - 7.4 11years32 Amarappa 30730 55 M - 22.5 148 240 29 1.1 - - 7 6years33 Budappa 4 40 M - 21.1 150 226 31 1.2 - - 5.9 4years34 Narsamma 26914 46 F - 31.2 136 200 28 1 - - 6.1 4years35 Khaja moinuddi 21462 48 M - 20.8 158 250 29 0.9 - - 7.2 5years36 Thipamma 19654 55 F - 23.3 170 300 33 1 - - 8.4 6years37 Damayanthi bai 21417 65 F - 22.4 223 247 25 0.9 + - 7.2 11years38 Md.Hussain 21441 72 M - 20.8 220 280 25 0.8 + - 8 16years39 Khaja bee 4274 70 F + 24.5 180 260 29 1.2 + - 7.8 16years40 Hanumanthu 108095 64 M - 20.9 220 280 34 0.7 - - 8 11years41 Anasuya bai 6141 55 F - 21.6 212 250 26 0.9 - - 8.2 6years
Micro Duration of DMAlb
HbA1cFBS PPBS B/U
Sr.Cre RP Htn BMIS.No
Name IP/OP No
Age
Sex
42 Ashiya 7774 80 F + 32.5 280 340 26 0.8 + - 10.8 17years43 Huligappa 33630 72 M + 22.5 158 267 34 0.8 + - 9.8 16years44 Laxmidevi 23497 45 F - 21.3 190 235 40 1.2 - - 7.6 4years45 Kristappa 28728 61 M - 23 180 240 36 1 - - 7.2 11years46 Chandrasekhar 9590 65 M - 18.8 164 232 32 1.2 + - 7 11years47 Channabasayya 93924 48 M + 23.1 200 280 20 0.9 + - 8.1 4years48 Vidyasagar 135282 53 M - 21.6 162 240 27 1.2 - - 6.9 6years49 Shankarappa 102741 48 M - 26.3 201 258 30 1 - - 7.3 4years50 Mahadevi 142188 53 F + 24.9 156 242 29 1.3 - - 6.7 6years51 Thikkayya 28233 63 M + 24.3 149 232 27 0.7 - - 6.2 11years52 Neelakanta 2269 70 M + 30.4 186 260 31 0.8 + - 7.1 16years53 Tamizuddin 22925 55 M - 25 188 239 27 1.1 - - 6.8 6years54 Bheemsen 14003 55 M + 32.5 181 252 28 1.2 + - 7.2 6years55 Veerabadrappa 3952 40 M + 21.9 129 189 29 0.7 - - 6.1 3years56 Devamma 22389 51 F - 26.4 130 198 23 1.1 + - 6 6years57 Banamma 4694 50 F + 28.2 163 280 39 0.9 + - 7 5years58 Ramappa 108673 66 M - 21.9 166 250 34 1.2 - - 6.8 11years59 Siddalingamma 138346 45 F - 21.5 160 240 28 0.9 - - 6.6 4years60 Saranamma 9563 65 F + 19.8 205 380 27 1.3 + - 8.2 12years61 Satyamma 19544 54 F + 24.5 174 250 19 1.1 + - 7.3 8years62 Lakshmi 27019 55 F + 21.3 235 310 18 1.2 + - 8.9 8years63 S A Kumar 19397 40 M - 19.8 127 203 18 0.8 - - 5.9 4years
Micro Duration of DMAlb
HbA1cFBS PPBS B/U
Sr.Cre RP Htn BMIS.No
Name IP/OP No
Age
Sex
64 Sharawan kuma 28250 44 M - 25 130 201 32 0.9 + - 5.9 4years65 Satyamma 19544 54 F - 21.9 140 180 23 0.8 - - 6.1 6years66 Banubayi 153507 42 F + 26.2 210 257 22 0.8 + - 7.2 5years67 Nagamma 10 60 F - 22.5 190 280 29 1.1 + - 8.1 6years68 Veerendra 1393 40 M + 31.2 149 190 32 1.1 + - 5.9 5years69 Narsa reddy 28253 48 M - 26.3 200 251 22 0.9 + - 7.8 5years70 Hanumanthappa 21459 55 M - 22.5 140 242 27 1.2 - - 6.2 6years71 Sarasamma 9563 65 F - 20.8 168 250 40 1.1 - - 6.6 11years72 khaja bee 4274 72 F + 29.7 178 212 42 1.3 + - 6 16years73 Laxmidevi 3823 78 F + 20.3 220 320 22 1.3 + - 10.7 18years74 Hanumavva 21472 60 F - 20.1 129 190 33 1 + - 6 7years75 Basamma 2392 60 F - 22.6 145 184 22 1.2 - - 5.9 6years76 Sharawan kuma 28250 44 M - 20 180 263 23 1 - - 7.2 3years77 Khaja sab 11841 60 M - 18.8 170 219 21 0.9 - - 6.4 6years78 Nagayya 18563 75 M + 22.4 272 348 29 1.1 + - 9.2 16years79 Eshwaramma 21967 75 F + 21.1 200 326 32 0.9 + - 8.8 16years80 Mahanthamma 28380 55 F - 19.8 172 250 22 1.1 - - 7.4 7years81 Jayamma 152238 45 F - 24.2 195 240 31 1.3 - - 6.4 4years82 Gouramma 12951 50 F - 21.9 165 230 33 1.2 - - 6.8 5years83 Zathamagala 152232 45 F - 19.5 190 230 39 0.9 - - 6.6 3years84 Shamshad 14773 40 F - 20.9 182 270 42 1 - - 7.2 3years85 Narsappa 23855 42 M - 21.9 105 230 22 1.2 - - 6.8 3years
Micro Duration of DMAlb
HbA1cFBS PPBS B/U
Sr.Cre RP Htn BMIS.No
Name IP/OP No
Age
Sex
86 Madhavamma 12459 55 F + 24.2 215 321 41 1 + - 8.9 8years87 Basavaraj 13008 50 M - 22.1 141 210 33 1.1 - - 6 5years88 Thulijabai 27926 54 F + 31.2 195 260 39 0.9 + - 8 8years89 Somayya 9595 74 M + 26.7 210 292 43 1.3 + - 9.2 16years90 Banubai 153507 42 F - 25 155 230 29 0.9 - - 6.8 3years91 Parvathi 145441 46 F + 22 167 198 44 1.4 + - 6.3 5years92 Somappa 5290 67 M - 225 200 250 32 1.2 - - 6.8 11years93 Basangouda 22034 41 M - 32.5 170 250 38 1.2 + - 7.2 5years94 Ananth rao 21675 48 M - 21.9 165 291 28 1.1 - - 7.7 4years95 Hanumanthu 22381 40 M - 23.3 161 245 22 1.1 - - 6.8 3years96 Mahaveer 5214 58 M + 24 176 290 40 0.9 + - 8 8years97 Dharam singh 11234 56 M - 23.2 190 290 39 1.1 - - 7.9 6years98 Rangappa 28119 53 M - 23 166 270 26 1.3 - - 8 6years99 Taranath 29672 40 M - 22.5 145 190 28 0.8 - - 5.8 3years100 Sharangouda 6127 65 M + 24.7 210 290 29 1.3 + - 8.2 12years