Determinants of insulin secretion and sensitivity in bangladeshi type 2 diabetic subjects

The relative contribution of insulin secretion and sensitivity in the development of type 2 diabetes mellitus (T2DM) vary from population to population due to the heterogeneous nature of the disease. The study was undertaken to evaluate the insulin secretory capacity and sensitivity in a Bangladeshi type 2 diabetic population and to explore the association of some of the anthropometric (BMI, WHR, MBP) and biochemical factors (glucose, lipids, HbA(1c)) known to modulate B-cell function and insulin action.

Ninety three T2DM and 70 age-matched control subjects were studied for their fasting glucose, lipids, HbA(1c) (by HPLC) and C-peptide (by ELISA). Insulin secretion (HOMA B) and insulin sensitivity (HOMA S) were calculated by homeostasis model assessment (HOMA).

Both insulin secretion and sensitivity were significantly reduced in diabetic as compared to control subjects (HOMA B%, geometric M +/- SD, 34.67 +/- 1.73 vs 104.71 +/- 1.34, p < 0.001; HOMA S%, 67.60 +/- 1.69 vs 85.11 +/- 1.54, p < 0.01). However, the discriminant function coefficient for HOMA B (1.142) was about 1.5 times higher than that for HOMA S (0.731). In T2DM, HOMA B had positive correlation with BMI (r = 0.362, p < 0.001) and inverse correlation with plasma glucose (r = - 0.701, p < 0.001) and HbA1c (r = - 0.612, p < 0.001). HOMA S was inversely correlated to BMI (r = - 0.274, p < 0.01), WHR (r = - 0.252, p < 0.05), plasma total cholesterol (r = - 0.240, p < 0.05) and triglycerides (r = 0.301, p < 0.01).

Both insulin secretory dysfunction and insulin resistance are present in Bangladeshi T2DM subjects, but B-cell dysfunction seems to be the predominant defect. BMI, plasma glucose and insulin are the major determinants of insulin secretory capacity; and generalized as well as central obesity, plasma glucose, total cholesterol, triglycerides and insulin are among the major determinants of insulin sensitivity in this population.