Aim: To assess the efficacy and safety of saxagliptin + metformin initial combination therapy compared with saxagliptin or metformin alone over 76 weeks (24-week short-term + 52-week long-term extension) in treatment-naÏve type 2 diabetes mellitus patients with inadequate glycaemic control.
Methods: In this phase 3, parallel-group, double-blind, active-controlled study, 1306 patients 18–77 years of age (HbA1c 8.0–12.0%) were randomized to saxagliptin 5 mg + 500 mg metformin, saxagliptin 10 mg + 500 mg metformin, saxagliptin 10 mg + placebo or 500 mg metformin + placebo. Blinded metformin was titrated during weeks 1–5 of the short-term treatment period in 500 mg/day increments to 2000 mg/day maximum in the metformin-based treatment groups. No titration of metformin was permitted during the long-term treatment period. A total of 888 patients completed the study (76 weeks), 613 without being rescued. Changes in HbA1c, fasting plasma glucose, 120-min postprandial glucose (PPG) and PPG-area under the curve (AUC) from baseline to week 76 were analysed using a repeated-measures model.
Results: At 76 weeks, adjusted mean changes from baseline HbA1c (95% CI) for saxagliptin 5 mg + metformin, saxagliptin 10 mg + metformin, saxagliptin 10 mg and metformin were −2.31 (−2.44, −2.18), −2.33 (−2.46, −2.20), −1.55 (−1.70, −1.40) and −1.79% (−1.93, −1.65), respectively (post hoc and nominal p < 0.0001 vs. metformin and saxagliptin monotherapies for saxagliptin 5 mg + metformin and saxagliptin 10 mg + metformin). The proportions of patients requiring rescue or discontinuation for insufficient glycaemic control were lower for saxagliptin + metformin than for either monotherapy. Little or no attenuation in PPG-AUC or 120-min PPG was observed between weeks 24 and 76 for saxagliptin + metformin, indicating persistent efficacy. Adverse event rates were similar across groups; hypoglycaemic events occurred at a low frequency.
Conclusion: Saxagliptin + metformin initial combination therapy was well tolerated and produced sustained glycaemic control for up to 76 weeks, with greater improvements in glycaemic parameters compared with either drug alone.