Insulin secretory defects and determinants of attending at a tertiary hospital in northern region of Bangladesh
K Hasnin, F Jebunnesa, L Ali
1 Rajshahi Diabetic Center, Rajshahi; 2Department of Biochemistry and Cell Biology, Bangladesh University of Health sciences (BUHS), Dhaka, Bangladesh
Aims: Rational management and prevention strategies for DM require an understanding on the burden, determinants and basic defects of the disorder which vary substantially among populations due to racial and environmental heterogeneity. Bangladesh has one of the largest diabetic populations in the world and its Rajshahi region has distinct geographical and cultural identity. Limited information on the prevalence, risk factors and basic defects of DM are present among Bangali population in general but, so far, no study has yet been conducted on any epidemiological or pathophysiological aspects of DM in Rajshahi population. This study was conducted to characterize the new patients attending the Rajshahi Diabetic Center which gives an idea about the proportion and risk indicators of DM among people in the Rajshahi region. At the same time the study also aimed to investigate the basic defects of T2 DM in this population. Methods: It was a hospital based observational analytic study with a hybrid research strategy having both cross-sectional and nested case-control designs. A multistage sampling technique was followed with 660 subjects in stage 1 for exploring the proportion of T2 DM and its association with clinical, socio-demographic and biochemical risk factors. In stage 2, a subgroup of subjects and non-diabetic controls, selected through a nested case-control design, were investigated for the basic defects (insulin secretory defect or insulin resistance) of DM and their association with various risk factors. Nutritional intake was assessed by food frequency questionnaire (24 hr dietary recall) method. Each subject went through OGTT following appropriate preparation and DM was diagnosed as per WHO Study Group Criteria. Blood glucose was measured by glucose oxidase method (Randox, UK) using a semi auto analyzer (300 MICROLAB). Lipids were measured by enzymatic methods. Serum insulin was measured by Chemiluminscent ELISA using mulite auto-analyzer (DPC, USA). Insulin secretory capacity (HOMA% B) and insulin sensitivity (HOMA% S) were calculated by homeostasis Model assessment method using HOMA-CIGMA software. Results: Out of the total subjects attending the OPD of RDC for the first time, 65% were found to suffer from T2 DM. The diabetic subjects were mostly (75%) of middle age (37% within 30-40 yrs and 37% within 41-50 yrs), only 2% cases had age <30 yrs and 23% had age >51yrs. There was a male preponderance in the proportion of T2 DM (56.4% female and 76.7% male). The diabetic subjects were mostly from middle (34.7%) to upper middle class (31.6%) background and by occupation females were mostly housewives (77.7%). Out of the diabetic subjects 37.7% had lower educational levels. The mean ±SD calorie consumption (2549±637) of the diabetic subjects was higher than that in non-T2 DM subjects and it came mainly from CHO (59.3%) and fat (55.9%). Based on WHO criteria for BMI for Asian population, 47.3% of subjects were normal weight, 36.1% over weight and 16.6% obese. All the newly diagnosed diabetic subjects in RDC were found to have poor diabetic control when judged by their fasting blood glucose level (mmol/l, M±SD) (13.4±4.4). Also when considered by blood glucose 2 hrs postprandial values, 97.9% of the T2 DM subjects had poor control. Lipid levels were also found to be largely uncontrolled in the diabetic subjects. On multiple regression, FBG was found to be associated with age (p=0.002) and occupation (p=0.026) in females and age (p=<0.001) and TG level (p=0.026) in males T2 DM subjects. Fasting serum Insulin was significantly higher in the T2 DM group as compared to non-T2DM (Serum Insulin level µIU/ml, M±SD) (13.5±4.9) subjects (p=<0.001). HOMA%B was (37±17) significantly lower in the T2 DM subjects as compared to non-T2 DM subjects. HOMA%S was (41±13) significantly lower in the T2 DM subjects as compared to non-T2 DM subjects. On multiple regression analysis with HOMA%B was found to be significantly associated with sex (<0.001) and education (p=0.010). On similar analysis, with HOMA%S was found to have significant association with males (p=0.002) and daily CHO intake (p=0.028). Conclusions: It may be concluded that both (HOMA%B) and (IR) constitute the basic defects of diabetes in Rajshahi population, but (HOMA%B) seems to be more predominant in these subjects. (HOMA%B) in Rajshahi population is associated with males and level of education and insulin resistance (IR) is associated with males and daily CHO intake.