Confirmation of impaired early insulin response to glycemic stimulus in nonobese mild diabetics.

The initial insulin responses of nonobese normal subjects and mild diabetics were analyzed during and after five-minute and two-minute infusions of 0.5 gm. per kilogram of glucose by vein. It was found that the two-minute injection elicited faster and significantly higher absolute hormonal output in both normals and diabetics, and that on both tests the normal subjects secreted significantly more insulin than did the mild diabetics. Comparison of respective "insulinogenic indexes" (net insulin output per unit of glycemic stimulus) showed that the corrected early insulin responses were in fact the same on both the five-minute and two-minute tests in normal subjects, and also in mild diabetics; but that the corrected insulin output was still twice as great in control subjects on both tests. It was also found that obese mild diabetics had significantly greater absolute insulin responses to both the five-minute and two-minute glucose injections than did their nonobese counterparts. These findings reconfirm that the earliest clinically recognizable state of diabetes mellitus is characterized by an impaired initial insulin secretory response to glycemic stimulus. They also indicate that valid interpretations of the influence of mild diabetes per se on the early insulin response can only be drawn from data obtained in nonobese individuals. Diabetes 24:17-24, January, 1975.