[Insulin sensitivity and pancreatic beta cell function changes during the transformation from normal to impaired...

To investigate the roles of insulin sensitivity and pancreatic beta cell function in the pathogenesis of type 2 diabetes.

70 subjects were recruited in a 3-year prospective study. During this period 9 subjects progressed from normal glucose tolerance (NGT) to impaired glucose tolerance (IGT) (progressing group), 45 remained same (remaining group) and 16 improved from IGT to NGT (improving group). Acute insulin secretion response (AIR(3 - 5)) during intravenous glucose tolerance test (IVGTT) was adopted to indicate the first phase insulin secretion with the ratio of insulin change from 0 min to 30 min to that of blood glucose from 0 min to 30 min (DeltaI(30)/DeltaG(30)) as the indicator of early insulin secretion and insulin sensitivity (ISI) was analyzed by the formula suggested by Cederholm during oral glucose tolerance (OGTT).

(1) For AIR(3 - 5), there were no differences of the baseline level and the 3-year follow-up state between the progressing group and remaining group; neither there were differences between the baseline level and the 3-year follow-up state in both groups. Meanwhile, in the improving group, AIR(3 - 5) increased after the 3-year follow-up time as compared with that at the baseline, but without significance. (2) For DeltaI(30)/DeltaG(30), there were no differences of the baseline level and the follow-up state between the progressing group and remaining group; neither there were differences between the progressing group and remaining group baseline level and the 3-year follow-up state in both groups. Meanwhile, in the improving group, there was no difference between that at baseline and at the follow-up. (3) For ISI, although there was no significant difference between the progressing group and remaining group at the baseline level, yet that at the 3-year follow-up state was different between the progressing group and remaining group with ISI in the progressing group decreased significantly; ISI in improving group increased significantly at the 3-year follow-up state as compared with that at the baseline level and there was significant difference between that in progressing group and remaining group at the 3-year follow-up state. (4) Only ISI, but neither AIR(3 - 5) nor DeltaI(30)/DeltaG(30), had effect on the change of glucose tolerance by logistic regressive analysis.

The ISI was the main change during the progress of NGT to IGT and the improvement of IGT to NGT, indicating that during the early progressive stage of type 2 diabetes, insulin sensitivity (insulin resistance) may play an important role.