Multicentric study was conducted to evaluate the efficacy of glimepiride in the oral hypoglycemic agents therapy of type 2 diabetic patients treated with glibenclamide so far, and to claim an adequate use of this new generation sulfonylurea. In 66 diabetic outpatients, glibenclamide was switched to glimepiride. After 6 months' therapy, a significant reduction in fasting plasma IRI was observed in relatively hyperinsulinemic patients. In addition, weight reduction was achieved in patients with insulin resistance during this study. These findings suggest that glimepiride improves insulin resistance in hyperinsulinemic patients treated with glibenclamide. Also, glimepiride is favored especially for overweight, insulin-resistant patients inadequately controlled by glibenclamide.