Rapid improvement in insulin binding to erythrocyte insulin receptors in non insulin dependent diabetes mellitus during therapy

Abstract

Insulin binding to erythrocyte receptors was studied in 36 newly diagnosed male subjects with NIDDM, treated with diet alone (Group I; n=10) or diet + glibenclamide (Group II; n=12) or diet + glibenclamide + metformin (Group III; n=14). Fourteen matched non-diabetic subjects were also studied as controls. Initially, mean (± SD) specific insulin binding was lower in NIDDM patients than in controls (p<0.001), due to decreased receptor number and affinity. Control of diabetes with short-term therapy (10 ± 2 days) resulted in significantly increased specific insulin binding in Groups II and III (p<0.001). A marginal increase was observed in Group I (p<0.01). The improved insulin binding observed in Group II and III patients after short-term therapy was maintained even after long-term therapy (9±1 months). Analysis of the insulin binding data by Scatchard plots and average affinity profiles indicated increased receptor number and affinity after short-term therapy. However, changes in affinity were reversed with long-term therapy in Groups II and III and the predominant effect appeared to be an increase in the number of binding sites.