Effect of glibenclamide in insulin-treated diabetic patients with a residual insulin secretion

We have studied the effect of the combination of a sulfonylurea (Hb 420 or glibenclamide) with insulin in 22 type II diabetic patients, treated with insulin and with residual insulin secretion (fasting plasma C peptide level greater than 0.2 pmol/ml). After a 3 week run-in period, the patients received either glibenclamide (7 mg of Hb 420 before breakfast and 3.5 mg before supper) or placebo in double blind fashion. Clinical and biological parameters (body weight, number of hypoglycemic episodes, daily insulin dose, fasting and postprandial glucose and C peptide levels after a standard meal) were collected during the basal (run-in) period and after 8 and 16 weeks of treatment. In the glibenclamide group, a significant increase in the number of hypoglycemic episodes was observed in spite of a 8 to 10% reduction in insulin requirements. A 18% reduction of both fasting and postprandial plasma glucose levels was found after 8 and 16 weeks of glibenclamide therapy. Concomitantly, a 35% increase of fasting and postprandial plasma C peptide levels occurred. The data suggest that the use of combined sulfonylurea and insulin therapy may be beneficial to type II diabetic patients with residual insulin secretion and poor glycemic control under insulin therapy alone.