Objective To determine the effect of self-efficacy on self-management behavior in type 2 diabetes mellitus (T2DM) patients based on propensity score matching (PSM). Methods All T2DM patients who were consecutively hospitalized in the endocrinology departments of 3 tertiary grade A hospitals in Xi′an City from December 2022 to June 2023 were recruited in this study. All the participants were surveyed with Self-Efficacy for Diabetes and Summary of Diabetes Self Care Activities. PSM was used to balance covariates related to self-management behavior, and logistic regression was used to analyze the impact of self-efficacy on self-management behavior. Results A total of 356 T2DM patients were enrolled, of which 285 (80.0%) had a low-to-medium self-efficacy level and 297 (83.4%) had a low-to-medium self-management behavior. There were significant differences between the low-to-medium level and high level patients in self-management behavior in terms of self-efficacy, marital status, years of illness, exercise or not, drinking or not (P<0.05). After PSM for the covariates at a ratio 1∶1, no statistical differences were observed in marital status and years of illness between the two groups. But significant difference was observed in the score of self-care activities among the patients with different levels of self-efficacy no matter before or after PSM (all P<0.05). Logistic regression analysis showed that before PSM, self-efficacy level, exercise or not, and drinking or not were independent risk factors for self-management behaviors (P<0.05); after PSM, self-efficacy level was an independent risk factor for self-management behaviors(P<0.05). Conclusion The level of self-efficacy affects self-management behavior in T2DM patients. And physicians should highlight the importance of their relationship in clinical practice.