Serum C-peptide after 6 months on glibenclamide remains higher than during insulin treatment

Serum C-peptide was measured fasting and 6 minutes after glucagon (1 mg given intravenously) in 49 patients with non-insulin-dependent diabetes mellitus, after 4 and 6 months of successive periods of treatment with insulin and oral hypoglycaemics (glibenclamide and metformin), given in random order. Glycaemic control was not significantly different on the two treatments, but C-peptide was much higher while the patients were on glibenclamide. We conclude that glibenclamide stimulates pancreatic insulin production even after 6 months treatment.