Glucose Tolerance in Non-Diabetic Adult Subjects of an Urban West-African Population

The present study was carried out to determine glucose tolerance and insulin sensitivity in adult subjects of a west African population. 103 subjects recruited in the town of Cotonou were included in the study. After anthropometric measurement, they were subjected to an oral glucose tolerance test (OGTT). Serum glucose and insulin levels were determined throughout the OGTT. Homeostatic model of assessment of insulin resistance (HOMA-IR), MATSUDA insulin sensitivity index (MATSUDA-ISI) and insulinogenic index (IGI) have been determined to evaluate insulin sensitivity and beta cells function. Normal glucose tolerance (NGT), isolated impaired fasting glucose (IFG), isolated impaired glucose tolerance (IGT) and combined glucose intolerance (CGI) were observed in respectively 53.40%, 1.94%, 35.92% and 8.74% of subjects. The prevalence of IFG and or IGT (IFG/IGT) was higher in obese subjects (66.67%) than in subjects with normal BMI (41.17%). Fasting hyperinsulinemia was observed in 82% of subjects. Mean values of HOMA-IR were not significantly different in NGT (6.86 ± 0.7) and in IFG/IGT subjects (7.47 ± 0.57). In contrast to HOMA-IR, mean value of Matsuda-ISI was significantly lower in IFG/IGT than in NGT subjects (1.47 ± 0.1 versus 1.96 ± 0.13, p<0.01). Matsuda-ISI values were also significantly lower in obese subjects (1.33 ± 0.12) than in subjects with normal BMI (1.93 ± 0.13). The mean insulinogenic index value in IFG/IGT subjects (42.5 ± 4.36) was not significantly different of that in NGT subjects (50.3 ± 5.21). These data show that the glucose tolerance disorders observed in subjects of the present study are more related to a decrease in insulin sensitivity than to an alteration of the beta cells function.