Objective: To study the effect of DPP-4 inhibitor combined with metformin on glucose and lipid metabolism and micro-inflammatory state in patients with type 2 diabetes mellitus complicated by metabolic syndrome. Methods: 60 patients with type 2 diabetes mellitus complicated by metabolic syndrome who were treated in the hospital between February 2015 and December 2016 were divided into control group (n=30) and observation group (n=30) according to the random number table method. Control group received metformin therapy alone, observation group received DPP-4 inhibitor combined with metformin therapy, and the differences in levels of glucose and lipid metabolism indexes and inflammatory factors were compared between the two groups of patients before and after treatment. Results:Before treatment, the differences in glucose and lipid metabolism index levels in peripheral blood as well as inflammatory factor contents in serum were not statistically significant between the two groups(P＞0.05). After treatment, the levels of glucose metabolism indexes FPG, FPI and HOMA-IR as well as lipid metabolism indexes TG and TC in peripheral blood of observation group were lower than those of control group while HDL-C level was higher than that of control group;the contents of inflammatory factors IL-6, CRP and TNF-α in serum were lower than those of control group (P<0.05). Conclusion: DPP-4 inhibitor combined with metformin therapy is more effective in controlling the glucose and lipid metabolism process and inhibiting the micro-inflammatory state in patients with type 2 diabetes mellitus complicated by metabolic syndrome.