31. 3, No. 1 & 2, Jan - Jun; July - Dec 2000 : 25-29 J. Baqai Med. Univ.

PREVALENCE SURVEY OF DIABETES AND STUDY OF ITS RISK FACTORS

Mohammad Aslam1, Momin Khan1 and Mohammad Zafal3

Abstract

A prevalence survey for diabetes was conducted in central district of Karachi city with a team of doctors and students as investigator~l.~. Each household filled a questionnaire regarding their height, weight, occupation, and type of diet, exercise, and family history of diabetes. Data has been compiled on statistical software "STATGRAPHIC", summarised in the form of tables and analysed by log- linear models5'. The prevalence rate of diabetes sharply increases with age, and therefore the prevalence increases with increase in age. The prevalence rate is generally higher in female as compared to male. Highest prevalence rate for both sexes was noted in the age group of 45-54 years.

The risk of diabetes in female is relatively high regarding each risk factor of diabetes. An obese female (WHR>0.84) is eight and half times more susceptible than the non-obese female (WHR<0.84). A female with positive family history of diabetes is 3.4446 times more vulnerable as compared to male, with a risk of 2.6964. The diabetic patients were significantly positively associated with positive family history having P-value < 0.00001. Moreover, the diabetic patients were significantly positively associated with P-value=0.03298.

Key Words

Prevalence, Diabetes, Risk Factors

Introduction

Persons having diabetes mellitus, if not properly treated, may face death as this disease still has no proper treatment.

This disease poses a social and economic problem8, because its medicines are very expensive. The Pakistani patients are very poor and the disease puts too much burden on their families. Public hospitals do not provide even life saving medicines to the poor people. The hospitals exhaust their funds in buying insulin for rich undeserving patients only.

The complications of diabetes are very broad as kidney failures, loss of eyesight, brain haemorrhage, delayed healing of wounds, cardiac problems. Pregnant women, with diabetes, face problems during and after delivery. Diabetes should not be taken lightly because of the chronic complication discussed aboveg.

1. Method and Research Design

A prevalence survey of diabetes mellitus was conducted in district central of Karachi City, with a view to study the age-specific prevalence rates, relationship of diabetes with its risk factors such as obesity, family history, sex, trend of diet taken by the people, and life pattern. Although a number of studies have been carried out in Indian subcontinent, very few prevalence studies have been carried out in Pakistan using WHO criteria''. Apparently no population-based studies have been reported from Pakistan using WHO criteria and this is the first phase of the survey.

A stratified sample of 967 adults, above 25 years of age, was selected from the district central of Karachi. The survey was carried out in two stages, of 327 and 670 subjects. According to the project protocol stratified random households from 11 blocks were selected and

'Assistant Professor, Department of Statistics, University of Karachi, Karachi-75270. 'Research Student, Department of Statistics, University of Karachi, Karachi-75270. 'Associate Professor, Department of Anatomy, Baqai Medical University, Super Highway, Karachi.

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persons with age of 25 or above and their sex was noted. At second stage, an examination centre was set-up for the survey. The B.P. apparatus and weighing machines were standardised daily. On the day of examination, after registration, a fasting blood sample (1 0- 14 hour fasting) was drawn and the subjects received 82.5gm glucose monohydrate load. During 2-hour period between the glucose load and the second blood sample, the standing height, weight (without shoes) and waist-hip ratio were recorded. Waist circumference was measured to the nearest cm at the midpoint between the illiac crest and the lower margin of the ribs with the subject standing and breathing normally. Hip circumference was measured around the buttocks posteriorly and anteriorly by the pubic symphysis. Obesity was defined as BM1>27kglm2 for men and BMI>25kg/m2 for female. Central obesity was defined as wait-hip ratio WHR>0.95 in men and WHR>0.85in women.

A fasting venous blood sample for glucose and serum cholesterol, serum triglyceride, HDL cholesterol and serum uric acid was collected. Every fourth sample was taken for fasting serum insulin levels. After the fasting blood sample a 82.5gm glucose monohydrate load dissolved in 250ml of water was given, and reading taken and a second blood sample for glucose estimation was collected two hours after the load. Time was caluculated from the first sip of glucose drink. A second blood sample for serum insulin was taken in the same subjects, after the glucose load.

Each household filled the printed questionnaire, the main questions being about the, prevalence of diabetes was 13%.

2. Data Compilation and Analysis

The data is comprised of three attributes at a time, which were considered as the potential risk factors of diabetes. These three attributes are diabetes mellitus (A), Family history (B) and obesity (C), each attributes having binary response either "Yes" or "No".

The data was analysed by fitting Log-Linear model, using the Statistics software Statgraphic". The log-linear model is useful to analyse the patterns of association among the attributes3-" and test the significance of association. It also fits the model of independence, two-factor interaction model, three factor interaction model and the interaction parameters and their significance was estimated.

The value of chi-square statistics was obtained as 46.789 with 4 degree of freedom and the P-value = 1.6873*10-', which leads to conclude that there were highly significant association among the three attributes in male group. The model with two factor interaction was fitted and it was observed that the chi-square value is 8.51023*10-', with one degree of freedom and the P-value=0.9265. It was concluded that the two factor interaction model is significanty adequate.

The two factor interaction was ,estimated and it was concluded that the diabetic male patients were significantly positively associated with positive family history reported earlier12. However it was negatively associated with "No" family history with P-value=0.000010913. The diabetic male patients were significantly positively associated with obesity but negatively associated with Non-obesity, with P- value=0.03298. The male with positive family history of diabetes were positively associated with obesity with P-value=0.0113232.

The value of chi-square statistics was obtained as 72.5257 with 4 degree of freedom and the P-value<0.001, which leads to conclude that there were very highly significant association among the three attributes in {emale group. The model of two factor interaction was fitted and it was found that the chi-square value is 6.5544*10-' with one degree of freedom and the P-value=0.9355. It was concluded that the two factors interaction model is significantly adequate.

3. Results and Discussion

The diabetic female patients were significantly positively associated with positive family history but negatively associated with "No" Family history with P-value<0.001. The diabetic female patients were significantly positively associated with obesity but negatively associated with Non-obesity with P-value<0.001.

The table 1 shows three attributes, diabetes mellitus (A), Sex (B) and obesity (C), each attributes having binary response either "Yes" or "No".

The data of table 1 was analysed by fitting Log-Linear model, using the Statistics software "Statgraphic"". This model is useful to analyse the patterns of association among the attributes an4 test the significance of association. It also fit the model of independence, two

Vol. 3, No. 1 & 2, Jan - Jun; July - Dec 2000 J. Baqai Med. Univ.

factor interaction model, three factors interaction model.

Table 1: Showing three attributes

The value of chi-square statistics was obtained as 104.387 with 4 degree of freedom and the P-value <0.001, suggesting a significant association among the three attributes in the male group. Applying the two factor interaction model gave a chi-square value of 1.39785 with one degree of freedom and the P-value=0.2371, concluding that the two factor interaction model is significantly adequate. The two factor interaction

Diabetes Mellitus (A)

Yes

No

Non-Diabetic Figure-1

Diabetic Female: YES

Sex (B)

Yes No

Obesity (C)

parameters of table 1 was also estimated which suggests that the following categories of attributes were significantly associated. The diabetes was significantly positively associated with obese male but negatively associated in female group with P-value ~0.001, and with Nan-obestity having P-value<0.001.

Table 2 indicates the relative riskL3 of male and female exposed to the risk factors "Family History", "WHR and "BMI". The relative risk of diabetes in female is relatively very high with regard to each risk factors of diabetes. For example the risk of diabetes to obese female on the basis of WHR is more than eight times as compared to male. An obese female, with WHR>0.84, is eight and half times more likely to be a diabetic patient than the non-obese female with WHR<0.84. In general the relative risk of diabetes in females are significantly higher with all risk factors as compared to male. So we may conclude that the females are more likely to be diabetic. A female with positive family history of diabetes is 3.4446 times more likely to be effected than the male with a risk factor of 2.6964.

No -

16

262

Table 2: Relative risk of diabetes b sex

Yes

54

246

Yes

23

67

No

40

257

The major risk factors of diabetes are "Family History (FH)" and "Waist-Hip Ratio (WEIR)". These factors are significantly associated with diabetes in female with P- Value=0.00004798 and 0.0077, respectively. However the risk factors (FH) significantly associated with P-value 0.0015 and (WHR) are not significantly associated with diabetes in male (Fig 1-4). In Figures 1-4, the proportion of area of quarter-circle shows the degree or strength of association among the categories of two attributesI4. In Figure 1 the area of quarter-circle in IV-quadrant is largest, suggesting a strong association between the categories "No diabetic" and "No family History" in female group and strongest association between the categories "No obesity" and "No diabetic" in female group is shown in Fig 2.

Risk Factors

Family History (FH)

BMI

WHR

Male

2.6964

1.2640

1.6809

Female

3.4446

2.2690

8.7295

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4. Conclusion

Diabetes can develop at any age; susceptibility gradually increases upto age 40, and then rapidly increases. After age 30 it affects woman more than man. The prevalence rates of diabetes are 9.0436% and 6.3683% for male and female, respectively. The overall prevalence rate of diabetes is 7.438% (Table 3).

Table 3: Age-Sex-specific prevalence rates of diabetes

The prevalence rates of diabetes are generally higher in female as compared to male with a maximum between the group 45-54 years i both sexes.

The percentage of diabetes obese, on the basis of the value of WHR, is 77.14% and 97.29% for male and female, respectively. The percentage of obese diabetes in female is significantly larger as compared to the male with P-Value <0.0001. People over the age of 40, who are obese and have a family history of diabetes must have their blood

Female

5.4%

18.9%

37.8%

24.3%

13.5%

Age Group

25 --- 34

35 --- 44

45 --- 54

55 --- 64

65+

Diabetic Male: YES

I

Male

2.8%

14.3%

42.86%

20.0%

20.4%

sugar level checked regularly. Diabetics must have their eyes tested and blood pressure and urine tested for kidney function, which are simple routine testL5.

Diabetes mellitus (DM) is an endocrine or hormonal disorder and is a long life disease16. This disease still has no proper treatment but it can be easily controlled under the guidance of competent doctors. The following suggestions are made:

1. Obesity is a very high risk factor to diabetics and should be controlled by using a balanced diet such as a glass of milk daily and vegetables. Sugar and sweet dishes should be avoided.

2. Persons with positive family history should be more careful about the weight, diet habits, life style and when over 40 years, one must check his blood sugar level regularly. Diabetic Male: YES

I

3. Exercise, especially, walking generally reduces blood glucose levels and therefore it is essential, that the intake of sugar is properly consumed and the effect of insulin on body cell improved.

4. Many psychologicl diseases also cause diabetes Women giving birth to a child weighing more than 8 pounds and having positive family history of diabetic, should avoid pregnancy in future.

5. Diabetic patients must have their eyes, blood pressure, and urine tested regularly, after every sixth months.

Vol. 3, No. 1 & 2, Jan - Jun; July - Dec 2000 J. Baqai Med. 'univ.

References

1. Aslam M. Prevalence survey of Diabetes, study of its risk factors and development of Statistical models, A project completed, funded by the University of Karachi, 1997 pp. 1-24.

2. Aslam M and Khan M. Prevalence survey of diabetes Mellitus in Pakistan, A technical report completed for the fulfilment of Master degree in Statistics, Department of Statistics, University of Karachi, Tech. Report No. 9705. 1998 pp.1-40.

3. Upton G J G. The analysis of Cross-Tabulated data. John Wiley & Sons Ltd. New York 1978.

4. Lee K S. An example for teaching some basic concepts in multidimensional contingency table analysis. The Amer Stats, 1978 32 (2), pp. 69-71.

5. Goodman A. The analysis of multidimensional contingency tables step-wise procedures and direct estimation methods for building models for multiple classifications. Technometrics, 1971 13, 33-61.

6. Agresti A. Categorical Data Analysis. 1990. John Wiely & Sons, New York.

7. Boyle J P Smith P J Thompson T J. Finite mixture models with concomitant information: assessing diagnostic criteria for diabetes, App. Statist. 1998. NO. 47, 3, pp. 393-404.

8. Akhtar M A. "Rational use of drugs in Diabetes Mellitus", Diabetes Digest. 1997. Vol. 10, No. 10.pp- 19-20.

9. Aschner P King H Torrado M T Rodriguez B M. Glucose Intolerance in Columbia, Diabetes Care, 1993. Vol. 16. NO. 1, pp.90-93.

10. World Health Organisation: Diabetes Mellitus: Report of WHO Study Group. Geneva, Tech. Rep. 1985. S. No 727.

11. "Statgraphic". A Statistical software. Statistical Graphic Corporation, 1988 U.S.A.

12. Assass B M. Samiuddin M Sarmara A A. and Meccawi, A. Heriditary Influences on diabetics, Pak. Jour. of Statistics, 1996. Vol. 12(3), pp. 259-264.

13. Collett D. Modelling Binary Data. 1991. Chapman & Hall, London.

14. Toit S H C Steyn A G W and Stumpf R M. Graphical Exploratory Data Analysis. 1986. Springer-Verlag, NY.

15. Sharif A. Diabetes is common both in urban and rural area: survey, Dawn 1996. Oct 26.

16. Richard A and Wagma M D. The New Complete Medical and Health Encyclopaedia. Vol. 11. Ferguson Publishing Company. 1990. U.S.A.