Insulin resistance study in diabetes mellitus type II and its correlation with obesity

Background: The earliest detectable abnormality in diabetes mellitus type II (DM II) is the impairment of body’s ability to respond to insulin, necessitating extra insulin secretion in an attempt to stimulate the desensitized cells. Obesity is considered as the single most important, reversible, causative environmental factor for insulin resistance (IR) aggravating the metabolic disturbance in DM II. Objectives: We aimed the study to evaluate the association of IR with DM II (its major outcome) and obesity (its main causative factor) in Pakistani diaspora. We measured IR in insulin resistance syndrome (IRS), DM II and obesity by using parameters namely fasting insulin level (FIL), homeostatic model assessment for insulin resistance (HOMA-IR), and quick insulin sensitivity check index (QUICKI), and evaluated their credibility. Materials and Methods: The study included 156 subjects (76 males and 80 females), out of which 101 were diabetics (with 59 on insulin, and 42 on oral hypoglycemics) with different duration of time in years, and 55 were non-diabetics. The data was analyzed after further subdividing the diabetics and non-diabetics into those having body mass index (BMI)<25, and those with BMI≥25. 101 had BMI≥25 (overweight/obese) [57 with BMI=25-29.9 (overweight), and 44 with BMI≥30 (obese)] and 55 had BMI= 1824.9 (normal weight). The individuals were then classified as those having insulin resistance syndrome (IRS) and those not having it. On the basis of NCEP criteria the associations between DM II, IRS, and obesity were evaluated. The credibility of three IR measuring parameters, namely, fasting insulin level (FIL), homeostatic model assessment (HOMA) and quick insulin sensitivity check index (QUICKI) was then assessed. Results: It was found that IRS prevailed up to 85% in diabetics and 76% in subjects with BMI≥25 out of which 84% IRS cases existed among obese (with BMI≥30). Similarly, 82% IRS cases were found diabetic and 72.4% with BMI≥25. FIL and HOMA showed significantly raised insulin and QUICKI showed significantly lower in IRS cases. But unlike FIL and HOMA, QUICKI did not show any significance when different subgroups of IRS cases were inter-compared. FIL and HOMA were also significantly raised in overweight/ obese individuals. QUICKI however showed significant but weak correlations with BMI. HOMA and QUICKI were significant in diabetics but FIL did not show significant difference. Conclusion: The results revealed strong correlation of obesity, IRS and DM II. HOMA was found better and sensitive index for evaluating IR in diabetes, IRS and obesity, than FIL alone or with QUICKI.