[Insulin release kinetics and insulin sensitivity in impaired glucose tolerance]

This review describes recent studies which have assessed early metabolic alterations in IGT. Several studies showed decreases in the initial insulin release in response to glucose without significant changes in insulin sensitivity in IGT. Fasting plasma proinsulin-like molecules were higher and the pulsatile insulin secretion was altered too. On the other hand, several studies has proposed that insulin resistance develops first. They have demonstrated that absolute day-long plasma insulin concentrations in response to glucose are not lower than normal and glucose metabolism is impaired. These results are still inconclusive. The physiological role of the initial insulin secretion may be clarified, while the effects of the subtle differences in age, obesity, fat distribution, and ethnic groups between IGT and NGT on insulin resistance may be differentiated.