Abstract
The aim of this study was to test if a beta-cell defect is associated to deterioration of glucose tolerance early during the natural history of the type 2 diabetes mellitus. In 41 overweight women, with macrosomic infants in their antecedent deliveries, measures of insulin response and insulin sensitivity were derived from a short (45 min) iv glucose test. The early (EIR) and the late (LIR) phase insulin responses and the insulin sensitivity index (Si) were calculated. According the response to 75 g oral glucose test the subjects were divided into two groups: Impaired glucose tolerance (IGT; n = 12), and normal glucose tolerance (NGT; n = 29). EIR was reduced in IGT group (14.9 +/- 3.6 vs 37.0 +/- 4.0; p < 0.002). Glucose tolerance during oral glucose tolerance test (OGTT), correlated inversely to EIR (r = -0.45; n = 41; p < 0.01). A strong correlation of EIR to LIR (r = 0.88; n = 41; p < 0.001) but no correlation between glucose tolerance and Si was found.