Efficacy of glimepiride in Japanese type 2 diabetic subjects

We investigated the efficacy of glimepiride, a third-generation sulfonylurea (SU), in Japanese type 2 diabetic patients in whom glycemic control had been inadequate with a conventional SU, gliclazide or glibenclamide. A total of 172 Japanese type 2 diabetic patients (HbA1C ≥ 7.0%), maintained on a conventional SU, were randomly assigned to the 3rd SU group (SU treatments switched to glimepiride) or the 2nd SU group (treatments not changed). The conventional SU was switched to the indicated doses of glimepiride (gliclazide 40 mg = glimepiride 1 mg, glibenclamide 2.5 mg = glimepiride 2 mg). After 6 months, glycemic control (HbA1C and fasting plasma glucose) had not changed significantly in either the 2nd or the 3rd SU group. The homeostasis assessment model of insulin resistance (HOMA-IR) in the 3rd SU group was decreased by more than 10% (p = 0.015), whereas no change was observed in the 2nd SU group. The triglyceride level was decreased by approximately 10% in the 3rd SU group, not a significant change (p = 0.080). Patients who had been treated with only SU, or treated with SU for a short time (less than 5 years), and who were also obese (BMI ≥ 25) or had a high HOMA-IR (HOMA-IR ≥ 3), showed significantly reduced insulin resistance. According to logistic regression analysis, high BMI (≥25) was the only variable predicting that glimepiride would more effectively improve HbA1C than conventional SU treatment. In conclusion, switching conventional SUs to glimepiride reduced insulin resistance without improving glycemic control. A notable finding of this study is that glimepiride was more beneficial in obese than in non-obese Japanese type 2 diabetic patients.