Objective: To analyze the influence of type 2 diabetes mellitus (DM) on the prognosis of oral squamous cell carcinoma (OSCC) patients with surgical treatment. Methods: The clinical data of 309 patients, who were diagnosed with OSCC and admitted to the same ward of Peking University Hospital of Stomatology from January 2014 to December 2017 were retrospectively reviewed, of whom, 104 were classified into DM group and 205 into non-DM group. The basic clinical data and follow-up results of the patients were analyzed and compared. Propensity score matching (PSM) was used to reduce confounding bias between the DM group and the non-DM group. Kaplan-Meier was used to calculate the survival rate of the two groups. Proportional hazards model was used to analyze the independent prognostic factors. The effect of glucose level on survival was analyzed. Results: After PSM, 77 patients in each group were matched and the variables were balanced. There were statistically significant differences in postoperative oral dysplasia and local recurrence between the two groups (P < 0.05). There was no significant difference in survival analysis between the two groups, but the survival rate of the DM group had the tendency to be lower than that of the non-DM group after matching. Univariate analysis and multiva-riate analysis both revealed that the tumor stage was an independent factor influencing the overall survival rate and tumor-specific survival rate of the OSCC patients (P < 0.05), while diabetes had no significant influence on the survival of the OSCC patients (P>0.05). Multivariate analysis showed that tumor stage, triglyceride level, preoperative mean capillary fasting blood glucose, postoperative mean postprandial blood glucose were indepen-dent prognostic factors for overall survival in the DM group. Tumor stage and mean postoperative postprandial blood glucose were independent prognostic factors for tumor-specific survival in the DM group. The risk of postoperative complications and distant metastasis in the DM group with poor glycemic control was higher than that in the good glycemic controls. Conclusion: There is no significant difference in overall survival and tumor-specific survival of the patients with or without DM. However, the possibility of mucosal dysplasia or local recurrence in the DM group is higher than that in the non-DM group. The tumor stage, triglyceride level and glycemic control of the patients with DM may affect their prognosis.