Glyburide versus glipizide in the treatment of patients with non-insulin-dependent diabetes mellitus.

Thirty-four adults with non-insulin-dependent diabetes mellitus were randomly assigned to receive either oral glyburide or oral glipizide in a multicenter comparative trial. Fasting blood glucose and hemoglobin A1c (HbA1c) were assessed at the beginning of the titration phase, the beginning of maintenance therapy, and the end of maintenance therapy. Maintenance therapy lasted approximately 3 months. The initial mean total dose of glyburide (5.4 mg) was significantly lower than that of glipizide (10.6 mg) (P = 0.04) and remained significantly lower at the beginning of maintenance therapy (7.8 mg versus 15.3 mg; P < 0.01) and at the end of the trial (10 mg versus 16.8 mg; P = 0.05). Although significant differences were not detected for fasting blood glucose or HbA1c, patients received higher total doses of glipizide compared with glyburide at the middle and final evaluations to maintain the fasting blood glucose between 3.9 and 10 mmol/L and HbA1c at < 9%. No serious adverse reactions were observed in any patient. These results indicate that doses of glipizide required to maintain blood glucose between 3.9 and 10 mmol/L and HbA1c at < 9% increased over time. Seventy-five percent of patients receiving glyburide were controlled with once-daily dosing compared with 29.4% of those treated with glipizide. Both glyburide and glipizide provide safe and effective treatment for patients with non-insulin-dependent diabetes mellitus, but more patients will benefit from once-daily therapy with glyburide.