Efficacy and safety of vildagliptin, Saxagliptin or Sitagliptin as add-on therapy in Chinese patients with type 2 diabetes inadequately controlled with dual combination of traditional oral hypoglycemic agents

Background: The oral DPP-4 inhibitors are new incretin-based therapies for treatment of type 2 diabetes. To assess the efficacy and safety of three DPP-4 inhibitors (Saxagliptin, Sitagliptin and Vildagliptin) as add-on therapy to dual combination of traditional oral hypoglycemic agents in Chinese type 2 diabetes patients. Methods: In this 24-week, randomized, open-label, parallel clinical trial, we enrolled inadequately controlled (glycosylated haemoglobin A1c [HbA1c] >= 7.5% to <= 10%) patients with type 2 diabetes, who were treated by dual combination of metformin and another traditional oral hypoglycemic agent (glimepiride, acarbose or pioglitazone). 207 patients had been randomized to add-on 5 mg saxagliptin group or 100 mg sitagliptin once daily group, or 50 mg vildagliptin twice daily group for 24 weeks. HbA1c, fasting and postprandial blood glucose (FBG and P2hBG), body weight, body mass index (BMI), episodes of hypoglycemia and adverse events were evaluated. Result: After 24 weeks, HbA1c, FBG, and P2hBG of each group were significantly decreased. (saxagliptin vs vildagliptin vs sitagliptin: HbA1c: -1.2% vs -1.3% vs -1.1%; FBG: -1.8 mmol/l vs -2.4 mmol/l vs -1.5 mmol/l; P2hBG: -3.4 mmol/l vs -3.7 mmol/l vs -3.2 mmol/l). The changes of HbA1c and P2hBG among the three groups had no significance. However, vildagliptin-added group showed the greatest reduction (p < 0.001), while, sitagliptin-added group showed the lowest reduction (p < 0.001) in terms of FPG changes. Proportions of patients achieving HbA1c < 7% at the end were similar in three groups (saxagliptin 59%, vildagliptin 65%, sitagliptin 59%). Mild hypoglycemia was commonly reported among the three groups (saxagliptin 6%, vildagliptin 2%, sitagliptin 3%). No significant between-group difference was shown in other AEs. Conclusion: The three gliptins showed almost similar glycemic control and incidence of adverse events. However, for FBG control, saxagliptin demonstrated superiority to sitagliptin, while, inferiority to vildagliptin.