OBJECTIVE: This multicenter open-label clinical trial compared the efficacy and safety of repaglinide/troglitazone combination therapy, repaglinide monotherapy, and troglitazone monotherapy in type 2 diabetes that had been inadequately controlled by sulfonylureas, acarbose, or metformin alone. RESEARCH DESIGN AND METHODS: Patients with type 2 diabetes (n = 256) who had inadequate glycemic control (HbA1c > or =7.0%) during previous monotherapy were randomly assigned to receive repaglinide (0.5-4.0 mg at meals), troglitazone (200-600 mg once daily), or a combination of repaglinide (1-4 mg at meals) and troglitazone (200-600 mg once daily). After a 4-6 week washout period, the trial assessed 22 weeks of treatment: 3 weeks (weeks 0-2) of forced titration, 11 weeks of fixed-dose treatment (weeks 3-13), and 8 weeks (weeks 14-21) of titration to maximum dose. Changes in HbA1c and fasting plasma glucose (FPG) values were measured. RESULTS: The combination therapy showed a significant reduction in mean HbA1c values (-1.7%) that was greater than with either type of monotherapy Repaglinide monotherapy resulted in a reduction of HbA1c values that was significantly greater than troglitazone (-0.8 vs. -0.4%) (P < 0.05). Combination therapy was more effective in reducing FPG values (-80 mg/dl) than either repaglinide (-43 mg/dl) or troglitazone (-46 mg/dl) monotherapies. Adverse events were similar in all groups. CONCLUSIONS: Combination therapy with repaglinide and troglitazone leads to better glycemic control than monotherapy with either agent alone. Repaglinide monotherapy was more effective in lowering HbA1c levels than troglitazone monotherapy Repaglinide/troglitazone combination therapy was effective and did not show unexpected adverse events.