Objective: To investigate the changes of coagulation function in T2DM with overweight and obese patients by thromboelastography (TEG). Methods: According to the inclusion and exclusion criteria, a total of 106 patients with T2DM diagnosed in the diabetes clinic of Caoyang Community Health Service Center, Putuo District, Shanghai from January 2019 to December 2020 were enrolled and randomized divided into a normal weight group (T2DM-NO, n=46) and an overweight/obesity group (T2DM-NO, n=60). General conditions and disease history of subjects were recorded. Blood routine tests, coagulation function, and TEG tests were performed. Results: Fasting blood glucose (FBG), low-density lipoprotein cholesterol (LDL-C), D-dimer, fibrinogen (FIB), whole blood viscosity, plasma viscosity and other blood routine and coagulation function indexes were significantly different between the T2DM-NO group and the T2DM-OW group. Among TEG parameters, R and K values in the T2DM-OW group were significantly shorter than those in the T2DM-NO group, while Ma value, α-angle and coagulation index (CI) were significantly increased (P<0.05). After controlling the above covariates, multivariate regression analysis showed that T2DM with overweight/obesity was significantly correlated with R, Ma, K and CI (P<0.05). Conclusion: T2DM with overweight and obesity showed hypercoagulability. TEG can be used as a clinical indicator to judge the coagulation status of patients and guide the treatment and prevention of macrovascular complications.