Randomized, Double-Blind, Phase 3 Trial of Triple Therapy With Dapagliflozin Add-on to Saxagliptin Plus Metformin in Type 2 Diabetes

OBJECTIVE: To compare the efficacy and safety of treatment with dapagliflozin versus that with placebo add-on to saxagliptin plus metformin in patients whose type 2 diabetes is inadequately controlled with saxagliptin plus metformin treatment. RESEARCH DESIGN AND METHODS: Patients receiving treatment with stable metformin (stratum A) (screening HbA1c level 8.0-11.5% [64-102 mmol/mol]) or stable metformin and a dipeptidyl peptidase-4 (DPP-4) inhibitor (stratum B) (HbA1c 7.5-10.5% [58-91 mmol/mol]) for ≥8 weeks received open-label saxagliptin 5 mg/day and metformin for 16 weeks (stratum A) or 8 weeks (stratum B) (saxagliptin replaced any DPP-4 inhibitor). Patients with inadequate glycemic control (HbA1c 7-10.5% [53-91 mmol/mol]) were randomized to receive placebo or dapagliflozin 10 mg/day plus saxagliptin and metformin. The primary end point was the change in HbA1c from baseline to week 24. Secondary end points included fasting plasma glucose (FPG) level, 2-h postprandial glucose (PPG) level, body weight, and proportion of patients achieving an HbA1c level of <7% (53 mmol/mol). RESULTS: Treatment with dapagliflozin add-on to saxagliptin plus metformin resulted in a greater mean HbA1c reduction than placebo (-0.82 vs. -0.10% [-9 vs. -1.1 mmol/mol], P < 0.0001). Significantly greater reductions in FPG level, 2-h PPG level, and body weight were observed, and more patients achieved an HbA1c level of <7% (53 mmol/mol) with treatment with dapagliflozin versus placebo. Adverse events were similar across treatment groups, with a low overall risk of hypoglycemia (∼1%). Genital infections developed in more patients with dapagliflozin treatment (5%) than with placebo (0.6%). CONCLUSIONS: Triple therapy with dapagliflozin add-on to saxagliptin plus metformin improves glycemic control and is well tolerated in patients whose type 2 diabetes is inadequately controlled with saxagliptin plus metformin therapy.