The effect of alrestatin on alanine-stimulated release of insulin and glucagon in man.

Alrestatin, an aldose reductase inhibitor, was administered orally to 10 normal men. Its effect on basal plasma glucose, insulin and glucagon levels and on the response of glucose, insulin and glucagon to an oral alanine load was assessed and compared to that of a placebo. There was a significant suppression of both the mean basal insulin level and the mean insulin response to alanine in the group pretreated with alrestatin as compared to the placebo group (p less than 0.05 at 0 and 60 min). Glucagon levels rose slightly in both groups but tended to be lower in the alrestatin-treated subjects, and blood sugar levels fell slightly. There was a significant inverse correlation between the mean insulin and glucose levels in individual subjects. The possible significance and mechanisms of insulin suppression are discussed.