Effect of Chronic Sulfonylurea Therapy on Plasma Insulin and Proinsulin Levels

Abstract

The effect of the chronic administration of glyburide, a potent sulfonylurea, on plasma glucose, insulin and proinsulin levels has been studied in a group of previously untreated adult-onset diabetics. Glucose tolerance was significantly improved over pretreatment values after 6 months of therapy. Total immunoreactive material (TIR) and plasma proinsulin (IRP) responses at 6 months were unchanged from control values. By 12 months the glucose tolerance had deteriorated slightly although remaining significantly better than control. Plasma TIR and IRP responses to oral glucose were both decreased after 12 months of therapy. The pattern of response to intravenous tolbutamide showed less change after chronic glyburide therapy than did the pattern of response to glucose.