Diabetes mellitus definition,classification,clinical features ,investigation
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Transcript of Diabetes mellitus definition,classification,clinical features ,investigation
DIABETES MELLITUS
DEFINATION, CLASSIFICATION ,CLINICAL FEATURES AND INVESTIGATIONS
FARRUKH MASOOD ,NMC
DEFINITION
• Diabetes is a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both. The chronic hyperglycemia of diabetes is associated with long-term damage, dysfunction, and failure of different organs, especially the eyes, kidneys, nerves, heart, and blood vessels.
(American Diabetes Association)
According to WHO Diabetes is if
Fasting Glucose =>7mmol or 126mg/dl
Random Glucose =>11.1mmol or 200mg/dl
INSULIN
• Human Insulin is a 51 amino acid dimeric protein composed of alpha and beta chains held together by disulphide bond.
• It is produced as a preproinsulin molecule by ribosomes, matures to proinsulin molecule in golgi apparatus and cleaves to insulin and C-peptide chain before its packing into secretory granules.
MECHANISM OF SECRETION
METABOLIC ACTIONS OF INSULIN
CLASSIFICATION OF DIABETES
• Type 1 Diabetes (IDDM)
• Type 2 Diabetes(NIDDM)
• Gestational Diabetes
• Other specific types
TYPE 1 DIABETES MELLITUS(IDDM)
• It occurs mostly in young group of patients <30 years.
• Insulin deficiency results due to destruction of beta cells
• Etiology
• T cell mediated autoimmune destruction of beta cells /glutamic acid decarboxylase antibodies (GAD Abs)
• Genetic predisposition (HLA- DR3 DR4 genes)
30-50% concordance in identical twins
• Environmental factors (viruses, excessive coffee intake, stress, cow milk in newborn )
It is usually associated with thyroid disease, Addison disease ,Pernicious anemia, Coelic disease.
TYPE 2 DIABETES MELLITUS (NIDDM)
• It mostly affects middle age and older people (>30 years)
• It occurs due to Insulin resistance and beta cell exhaustion (relative insulin deficiency)
• High insulin levels in the early stage is characteristic.
• Etiology
• Central obesity ( ↑FFA compete with glucose for oxidation ,adipokines decreases sensitivity of insulin
receptors ,inhibits gluconeogenesis)
• Metabolic syndrome (obesity, hypertension,↑LDL,↑TAGs,etc)
• Genetic predisposition (TCFL2 gene)
• BMI >30 kg/m2
• Pregnancy
MATURE ONSET DM (MODY)
A type of type 2 DM occurring in young people
It is further divided into
MODY 1 (HNF 4a deficiency)
MODY 2 (glucokinase deficiency)
MODY 3 (HNF 1a deficiency)
MODY 4 (IPF-1 deficiency)
MODY 5 HNF-1b deficiency)
GESTATIONAL DIABETES
• It is the hyperglycemia occurring for the first time during pregnancy
• Placental hormones reduce the sensitivity of insulin receptors resulting in hyperglycemia and insulin doesn’t meet body requirement and beta cell exhaustion occurs
OTHER SPECIFIC TYPES
• Genetic defects of beta cells
• Genetic defects of insulin action e.g lipodystrophy
• Pancreatic disease (pancreatitis,cystic fibrosis,neoplasm,hemochromatosis)
• Drug induced DM (steroids,thiazides,diuretics)
• Viral (congenital rubella,mumps, coxasackie )
• Uncommon form of immune mediated DM
• Endocrine Induced DM (thyrotoxicosis,Cushing syndrome,acromegaly,pheochromocytoma)
CLINICAL FEATURES
• Polyuria
• Polyphagia
• Polydipsia
• Fatigue
• Weight loss
• Dehydration
• Visual blurring
• Recurrent infections
• Delayed healing
• In complicated case
• Peripheral gangrene
• Tingling and numbness
• Diabetic retinopathy
• Nephrosclerosis
INVESTIGATIONS
• Urine Testing
• Blood Testing
• Glycated hemoglobin
• Serum Electrolytes and renal parameters
URINE TESTING
• Testing the urine for glucose with dipsticks is a common practice for detecting diabetes.
• Preferably it should be checked after 2 hrs of meal for its maximum sensitivity
• It may be false positive in pregnancy and with some drugs
• Ketonuria can also be detected in the urine by dipsticks
• To check for ketone bodies in urine ,nitroprusside reaction is used
• Ketonuria may aslo be false positive in case of prolonged strenuous exercise ,vomiting, dehydration but if with glycosuria diabetes is most likely diagnosis
• Standard dipstick testing for albumin detects urinary albumin at concentration >300mg/dl.
• Microalbuminuria in the absence of UTI is an indicator of diabetes.
BLOOD TESTING
Normal fasting blood glucose =<7mmol or 126mg/dl
Normal random blood glucose =<11.1mmol or 200mg/dl
In diabetics
FBG = ≥126mg/dl
RBG = ≥200mg/dl
• Oral Glucose Tolerance Test (also called the OGTT) : The OGTT is a two-hour test that checks your blood glucose levels before and 2 hours after you drink a special sweet drink. It tells the doctor how your body processes glucose. Diabetes is diagnosed at 2 hour blood glucose of greater than or equal to 200 mg/dl
PRE DIABETICS
• Before people develop type 2 diabetes, they almost always have "prediabetes" — blood glucose levels that are higher than normal but not yet high enough to be diagnosed as diabetes.
• Doctors sometimes refer to prediabetes as impaired glucose tolerance (IGT) or impaired fasting glucose (IFG), depending on what test was used when it was detected. This condition puts you at a higher risk for developing type 2 diabetes and cardiovascular disease.
• Results indicating prediabetes are:
• An A1C of 5.7% – 6.4%
• Fasting blood glucose of 100 – 125 mg/dl
• An OGTT 2 hour blood glucose of 140 mg/dl – 199 mg/dl
GLYCATED HEMOGLOBIN
• Glycated hemoglobin provides an accurate and objective measure of glycemic control over a period of 2-3 months
• In diabetes ,the slow non enzymatic covalent attachment of glucose to hemoglobin increases the amount of Hb1ac relative to HbA
• To be diabetic, Hb1ac should be ≥6.5%
• Renal function tests should be evaluated as creatinine may raise in diabetes
• Electrolyte balance should be evaluated in case of diabetic ketoacidosis