Efficacy and safety of sitagliptin added to ongoing metformin and rosiglitazone combination therapy in a randomized placebo-controlled 54-week trial in patients with type 2 diabetes

Background: New therapeutic approaches are needed to improve glycemic control in patients with type 2 diabetes (T2D), a progressive disorder that often requires combination therapy. The present study assessed the efficacy and safety of sitagliptin as add-on therapy to metformin and rosiglitazone in patients with T2D. Methods: The present study was a randomized double-blind placebo-controlled parallel-group 54-week study conducted at 41 sites across North and South America, Europe, and Asia in 278 patients with HbA1c ranging from >= 7.5% to <= 11.0% despite ongoing combination therapy with metformin (>= 1500 mg/day) and rosiglitazone (>= 4 mg/day). Patients were randomized (2: 1) to receive sitagliptin 100 mg or placebo once daily. The main outcome measure was change from baseline in HbA1c at Week 18. Results: Mean baseline HbA1c was 8.8%. The mean placebo-adjusted change from baseline in HbA1c with sitagliptin treatment was) 0.7% (P < 0.001) at Week 18 and) -0.8% (P < 0.001) at Week 54. There were also significant (P < 0.001) reductions in 2-h post-meal glucose and fasting plasma glucose compared with placebo at Weeks 18 and 54. Significantly higher proportions of sitagliptin-than placebo-treated patients had HbA1c<7.0% at Weeks 18 (22% vs 9%; P = 0.003) and 54 (26% vs 14%; P = 0.015). Changes in body weight and the rates of adverse events overall, hypoglycemia, and gastrointestinal adverse events were similar in the sitagliptin and placebo groups during the 54-week study. Conclusions: In patients with T2D, the addition of sitagliptin for 54 weeks to ongoing therapy with metformin and rosiglitazone improved glycemic control and was generally well tolerated compared with placebo.