Potentiation of insulin release by glucose in man. I. Quantitative analysis of the enhancement of glucose-induced insulin secretion by pretreatment with glucose in normal subjects.
The effect of repeating a 60 min glucose infusion at a 40 to 70 min interval was investigated after an overnight fast in 14 healthy, non-obese subjects with normal glucose tolerance and normal insulin response to glucose administration. When a hyperglycaemic plateau of around 300 mg/100 ml was induced by the first glucose infusion, the insulin response to a second challenge was enhanced over the range of stimulations used. Both the early and late phase insulin responses were amplified, the enhancement being more marked with higher stimulatory levels of glucose. The blood glucose-insulin dose-response curve became steeper after pretreatment with glucose, the stimulatory threshold level not being altered. These findings suggest that the synergism between the glucose pretreatment, and the insulin releasing effect of glucose, is of multiplicative type, resulting in increase of the maximum effect of the glucose.