Basal Insulin Resistance and Secretion in Nigerians With Type 2 Diabetes Mellitus

Aim: The objective of this study was to estimate basal insulin resistance (IR) and insulin secretion (IS) in Nigerians with type 2 diabetes mellitus (T2DM). Methods: The homeostasis model assessment (HOMA) method was used to estimate basal IR and IS in 146 Nigerians with T2DM and in 33 controls at the University of Nigeria Teaching Hospital (UNTH), Enugu, Nigeria. Correlations and multiple regression analysis between Box-Cox-transformed IR and log-transformed IS and anthropometric indices were carried out. Results: IR and reduced IS were present, respectively, in 139 (95.5%) and 109 (74.7%) of the diabetic subjects and in 25 (75.8%) and 4 (12.1%) of the controls. In the diabetic subjects, age at diagnosis, duration of diabetes, waist circumference (WC), and body mass index (BMI) correlated significantly with IR (r = -0.2399, P = 0.0035; r = 0.1993, P = 0.0166; r = 0.2267, P = 0.0059; r = 0.2082, P = 0.0120; respectively), whereas duration of diabetes, WC, and BMI correlated significantly with IS (r = -0.2166, P = 0.0091; r = 0.3062, P = 0.0002; r = 0.2746, P = 0.0008; respectively). Age at diagnosis, WC, and duration of diabetes were significant predictors of IR (beta = -0.0161, P < 0.001; beta = 0.0121, P = 0.002; beta = 0.0138, P = 0.042; respectively), whereas duration of diabetes and WC significantly predicted IS (beta = -0.0159, P = 0.025; beta = 0.0155, P < 0.001). Conclusions: This study shows that both IR and reduced IS are major features of T2DM in Nigerians and that WC consistently correlated and predicted IR. WC measurement is simple and ideal in resource-poor settings for the detection of IR and abdominal obesity. The apparent rarity of coronary heart disease (CHD) in black Africans with T2DM despite a high prevalence of IR warrants further investigation.