Abstract: Objective   To assess the effects and safety of sitagliptin combined with metformin in treating type 2 diabetes mellitus (T2DM). Methods   CNKI， Wanfang， VIP， PubMed， Cochrane Library， MEDLINE and other foreign language database were serached. The randomized controlled studies both at home and abroad about the efficacy and safety of sitagliptin combined with metformin and metformin alone in treating T2DM were enrolled into this study. The methodological value of the included studies were judged， the data conformed to the standard were extracted and RevMan 5.3 software was performed. Results   A total of 20 studies were included  (n=3 359).  Compared with MET alone， SITA+MET obviously reduced the fasting blood glucose (FBG)， postprandial 2 hours blood glucose (2 hPG)， glycosylated hemoglobin (HbA1c)， body mass index (BMI) and insulin resistance index (HOMAIR)， but no significant difference was found  in fasting plasma insulin(FINS);  SITA+MET had no obvious increase in the incidence of hypoglycemia， gastrointestinal reaction rate was significantly reduced. Conclusion   SITA+MET can obviously reduce FBG， 2 hPG， HbA1c， BMI and HOMAIR of T2DM patients，the incidence of hypoglycemia is low， so it has higher safety and low incidence of gastrointestinal reaction， the patients have better tolerability.

Key words: diabetes mellitus, type 2, metformin, sitaglipin, meta analysis