Efficacy and safety of saxagliptin in combination with metformin compared with sitagliptin in combination with metformin in adult patients with type 2 diabetes mellitus

Background Dipeptidyl peptidase-4 inhibitors improve glycaemic control in patients with type 2 diabetes mellitus when used as monotherapy or in combination with other anti-diabetic drugs (metformin, sulphonylurea, or thiazolidinedione). This 18-week, phase 3b, multicentre, double-blind, noninferiority trial compared the efficacy and safety of two dipeptidyl peptidase-4 inhibitors, saxagliptin and sitagliptin, in patients whose glycaemia was inadequately controlled with metformin. Methods Adult type 2 diabetes mellitus patients (N = 801) with glycated haemoglobin (HbA(1c)) 6.5-10% on stable metformin doses (1500-3000 mg/day) were randomized 1 : 1 to add-on 5 mg saxagliptin or 100 mg sitagliptin once daily for 18 weeks. The primary efficacy analysis was a comparison of the change from baseline HbA(1c) at week 18 in per-protocol patients. Noninferiority was concluded if the upper limit of the two-sided 95% confidence interval of the HbA(1c) difference between treatments was <0.3%. Results The adjusted mean changes in HbA(1c) following the addition of saxagliptin or sitagliptin to stable metformin therapy were -0.52 and -0.62%, respectively. The between-group difference was 0.09% (95% confidence interval, -0.01 to 0.20%), demonstrating noninferiority. Both treatments were generally well tolerated; incidence and types of adverse events were comparable between groups. Hypoglycaemic events, mostly mild, were reported in approximately 3% of patients in each treatment group. Body weight declined by a mean of 0.4 kg in both groups. Conclusions Saxagliptin added to metformin therapy was effective in improving glycaemic control in patients with type 2 diabetes mellitus inadequately controlled by metformin alone; saxagliptin plus metformin was noninferior to sitagliptin plus metformin, and was generally well tolerated. Copyright (C) 2010 John Wiley & Sons, Ltd.