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Keywords:

  • DPP-4;
  • metformin;
  • saxagliptin;
  • type 2 diabetes

Aim:  The study aim was to evaluate the efficacy and safety of initial combination therapy with saxagliptin + metformin vs. saxagliptin or metformin monotherapy in treatment-naïve patients with type 2 diabetes (T2D) and inadequate glycaemic control.

Methods:  In this multicentre, randomized, double-blind, active-controlled phase 3 trial, 1306 treatment-naïve patients with T2D ≥18 to ≤77 years, glycosylated haemoglobin (HbA1c) ≥8 to ≤12%, fasting C-peptide concentration ≥1.0 ng/ml, body mass index ≤40 kg/m2 were randomized to receive saxagliptin 5 mg + metformin 500 mg, saxagliptin 10 mg + metformin 500 mg, saxagliptin 10 mg + placebo or metformin 500 mg + placebo for 24 weeks. From weeks 1–5, metformin was uptitrated in 500-mg/day increments to 2000 mg/day maximum in the saxagliptin 5 mg + metformin, saxagliptin 10 mg + metformin and metformin + placebo treatment groups. The main outcome measure was HbA1c change from baseline to week 24. Selected secondary outcomes included change from baseline to week 24 in fasting plasma glucose (FPG), proportion of patients achieving HbA1c <7% and postprandial glucose area under the curve (PPG-AUC).

Results:  At 24 weeks, saxagliptin 5 mg + metformin and saxagliptin 10 mg + metformin demonstrated statistically significant adjusted mean decreases vs. saxagliptin 10 mg and metformin monotherapies in HbA1c (−2.5 and −2.5% vs. −1.7 and −2.0%, all p < 0.0001 vs. monotherapy) and FPG (−60 and −62 mg/dl vs. −31 and −47 mg/dl, both p < 0.0001 vs. saxagliptin 10 mg; p = 0.0002 saxagliptin 5 mg + metformin vs. metformin; p < 0.0001 saxagliptin 10 mg + metformin vs. metformin). Proportion of patients achieving an HbA1c <7% was 60.3 and 59.7%, respectively, for saxagliptin 5 mg + metformin and saxagliptin 10 mg + metformin (all p < 0.0001 vs. monotherapy). PPG-AUC was significantly reduced [−21 080 mg·min/dl (saxagliptin 5 mg + metformin) and −21 336 mg·min/dl (saxagliptin 10 mg + metformin) vs. −16 054 mg·min/dl (saxagliptin 10 mg) and −15 005 mg·min/dl (metformin), all p < 0.0001 vs. monotherapy]. Adverse event occurrence was similar across all groups. Hypoglycaemic events were infrequent.

Conclusion:  Saxagliptin + metformin as initial therapy led to statistically significant improvements compared with either treatment alone across key glycaemic parameters with a tolerability profile similar to the monotherapy components.