Increase in insulin response after treatment of overt maturity-onset diabetes is independent of the mode of treatment.

The changes in insulin response to a 100 g glucose tolerance test after treatment by diet, sulphonylurea and insulin were compared in non-ketotic diabetic patients who had fasting blood glucose concentrations higher than 160 mg/100 ml. Patients were selected so that their pre-treatment and post-treatment blood glucose levels were comparable between different treatment groups. Their insulin responses were poor initially but increased significantly when the diabetic state was improved by each treatment. The degree of improvement of insulin response was similar between different treatment groups, when their fasting blood glucose decreased below 140 mg/100 ml and the glucose tolerance curves were improved to a similar extent. Pre- and post-treatment sigma IRI values (sum of insulin values during glucose tolerance test, mean +/- SD) were 102 +/- 50 and 200 +/- 37 microU/ml in diet-treated group (n = 28), 90 +/- 40 and 195 +/- 53 microU/ml in sulphonylurea-treated group (n = 48), and 83 +/- 28 and 193 +/- 38 microU/ml in insulin-treated group (n = 13), respectively. The data suggest that the poor insulin response in overt diabetes results not only from an inherent insensitivity of B-cells to glucose but also from the metabolic derangement of diabetes. Poor insulin response and overtly diabetic metabolism seems to form a vicious cycle.