〔Abstract〕 Objective To investigate the clinical efficacy of sitagliptin combined with metformin in the treatment of elderly patients with type 2 diabetes mellitus (T2DM). Methods A total of 160 T2DM patients admitted to the 900th Hospital of PLA Joint Logistic Support Force from January 2019 to December 2019 were selected and randomly divided into observation group and control group, with 80 patients in each group. The control group was treated with metformin, and the observation group was treated with sitagliptin. The differences of fasting blood glucose (FPG), 2h postprandial blood glucose (2hPG), glycosylated hemoglobin (HbA1c) and treatment safety were compared between the two groups. Results There were no significant differences in FPG, 2H PG and HbA1c levels between the two groups before treatment (P > 0.05). After treatment, the levels of FPG, 2H PG and HbA1c in observation group were lower than those in control group, the differences were statistically significant (P < 0.05). The incidence of adverse reactions in observation group was 7.5%, and there was no statistical significance compared with 11.3% in control group (P > 0.05). Conclusion Sitagliptin combined with metformin has a significant overall effect in the treatment of elderly T2DM, which can promote blood glucose reduction and has a high therapeutic safety