An evaluation of the therapeutic effects and dosage equivalence of glyburide and glipizide.

Nineteen noninsulin-dependent diabetic patients [ten women, nine men, aged 36-80 years (mean +/- SE 56.8 +/- 2.7 years)] were randomized to receive either glyburide or glipizide for 16 weeks, in a double-blind crossover fashion. A 2-week washout period preceded each treatment period. The patients measured blood glucose concentrations 16 times weekly using Chemstrip-bG. The medication dosages were titrated to achieve fasting blood glucose concentrations of less than or equal to 6.2 mM and preprandial and postprandial concentrations of less than or equal to 9.0 mM, or to a total daily dose of 20 mg for glyburide and 40 mg for glipizide. Glyburide therapy resulted in a significant decline in fasting, preprandial, postprandial and bedtime blood glucose levels, while glipizide treatment led to a significant lowering of postprandial and bedtime blood glucose. Furthermore, fasting, preprandial and postprandial blood glucose concentrations were significantly lower during glyburide as compared to glipizide treatment phase. Glycosylated hemoglobin levels were decreased only with glyburide. Serum C-peptide and insulin concentrations were not altered over the entire study. The mean final daily dose of glyburide (15.4 +/- 1.6 mg) was markedly lower than that of glipizide (29.7 +/- 3.1 mg). Thus, in this patient population, glyburide was twice as potent on a weight basis than glipizide.