Effects of combined insulin-sulfonylurea therapy in type II patients.

We conducted a double-blind crossover study to determine which patient characteristics best predict a beneficial response to combined insulin-glyburide therapy. Glyburide (15 mg/day) or placebo was added to the treatment regimen of 31 insulin-treated type II (non-insulin-dependent) diabetic subjects. During glyburide therapy, there was a significant improvement in glycemic control with a reduction in glycosylated hemoglobin from 9.9 +/- 1.3 to 9.1 +/- 1.3% (P less than .001). Patients who responded had higher fasting C-peptide levels (P less than .001) and shorter durations of insulin therapy (P less than .01) than those who did not respond. Glyburide withdrawal was associated with a greater than expected deterioration in glycemic control. Patients on insulin therapy for greater than 8 yr are unlikely to benefit significantly from the addition of glyburide to their treatment regimen.