Effects of a fixed-dose combination of sitagliptin and metformin versus respective monotherapies in newly diagnosed type 2 diabetic subjects

Metformin is considered as a backbone therapy for type 2 diabetes (T2DM) management. Many patients need treatment with combination therapy. In India, multiple fixed-dose combinations with metformin are available. The study was done to compare the efficacy and safety of sitagliptin plus metformin combination versus metformin and sitagliptin monotherapy in newly diagnosed T2DM subjects. This was an open-label, randomized, parallel group, prospective and single centre study, in 60 subjects with T2DM. The subjects received either metformin 500 mg, sitagliptin 50 mg or fixed-dose combination of metformin 500 mg plus sitagliptin 50 mg. All study medicines were given twice daily for 12 weeks. Glycaemic control (HbA1c, fasting and postprandial blood glucose) and body mass index (BMI) were evaluated as efficacy parameters while safety was evaluated by reporting adverse events. Significant reduction in HbA1C level was seen in all three groups (P = 0.0001). HbA1C reduction was significantly higher in the combination group compared to metformin monotherapy (P = 0.0072). Fasting blood glucose (FBG) level reduced significantly in all three groups (P = 0.0001). The reduction in fasting blood glucose was significantly higher with combination compared to sitagliptin monotherapy (P = 0.0060). Postprandial blood glucose (PPG) also reduced significantly in all three groups (P = 0.0001). The reduction with sitagliptin was statistically higher compared to metformin (P = 0.0155). The combination treatment resulted in significantly higher reduction of PPG compared to sitagliptin monotherapy (P = 0.0160). Body mass index reduced significantly in all three groups (P = 0.0001). Reduction in BMI was significant with combination treatment compared to sitagliptin monotherapy (P < 0.05). Overall, study medications were well tolerated. The incidence of adverse event was 11.7 %. No serious adverse event was reported in the study. In newly diagnosed, drug naïve, type 2 diabetes mellitus management, fixed-dose combination of sitagliptin plus metformin is effective and well tolerated. Due to its multiple benefits, it can be used as a suitable option for selected subjects requiring combination therapy in type 2 diabetes mellitus.