Aim: To assess efficacy and safety of saxagliptin added to metformin versus placebo plus metformin in Asian patients with type 2 diabetes mellitus (T2DM) and inadequate glycemic control on metformin alone. Methods: Adults (HbA(1c) 7.0-10.0%, on stable metformin >= 1500 mg/day) were randomized 1:1 to saxagliptin 5 mg daily plus metformin (n = 283) or placebo plus metformin (n = 287). The primary end point was HbA(1c) change from baseline to Week 24. Results: Saxagliptin plus metformin provided significant adjusted mean decreases versus placebo plus metformin (p <= 0.0052) in HbA(1c) (-0.78% versus -0.37%), fasting plasma glucose (-1.14 mmol/L versus -0.58 mmol/L), and postprandial glucose area under the curve from 0 to 180 min (-315 mmol min/L versus -160 mmol min/L). Significantly more saxagliptin-treated patients achieved a therapeutic glycemic response (HbA(1c) < 7.0%) (46.5% versus 30.5%; p = 0.0001). The proportion of patients experiencing adverse events (excluding hypoglycemia) was similar for saxagliptin plus metformin (42.8%) versus placebo plus metformin (40.8%). Hypoglycemic events were reported in 1.4% of patients in each group. Conclusion: Saxagliptin added to metformin significantly improved glycemic control and was well tolerated in Asian patients with T2DM who had inadequate glycemic control with metformin and diet and lifestyle modification. (C) 2011 Elsevier Ireland Ltd. All rights reserved.