Troglitazone or metformin in combination with sulfonylureas for patients with type 2 diabetes?

BACKGROUND. Combination oral therapy is often used to control the hyperglycemia of patients with type 2 diabetes. We compared the effectiveness of metformin and troglitazone when added to sulfonylurea therapy for patients with type 2 diabetes who had suboptimal blood glucose control. METHODS. We used a randomized 2-group design to compare the efficacy, safety, and tolerability of troglitazone and metformin for patients with type 2 diabetes mellitus that was inadequately controlled with diet and oral sulfonylureas. Thirty-two subjects were randomized to receive either troglitazone or metformin for 14 weeks, including a 2-week drug-titration period. The primary outcome variable was mean change in the level of glycosylated hemoglobin (Hb A_1c) from baseline. Secondary outcomes included mean changes from baseline in fasting plasma glucose and C-peptide levels, renal or metabolic side effects, and symptomatic tolerability. RESULTS. The addition of either troglitazone or metformin to oral sulfonylurea therapy significantly decreased Hb A_1c levels. Both treatment regimens also significantly reduced fasting plasma glucose and C-peptide levels. We found no significant differences between the treatment arms in efficacy, metabolic side effects, or tolerability. CONCLUSIONS. Our results demonstrate that troglitazone and metformin each significantly improved Hb A_1c, fasting plasma glucose, and C-peptide levels when added to oral sulfonylurea therapy for patients with type 2 diabetes who had inadequate glucose control.