Background: The prognosis of percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) between patients with diabetes mellitus (DM) and those without DM is unknown. This study aimed to investigate whether DM has adverse effects on CTO PCI patients. Methods: This single- center retrospective study included consecutive patients who underwent PCI for CTO at the China-Japan Friendship Hospital (Beijing, China) between January 2016 and April 2019. The clinical outcomes during follow-up were compared between patients with DM and those without DM. Results: The analysis included 187 patients (152 males) aged 62.6 +/- 11.5 years. A total of 99 participants (52.9%) had DM, which involved a higher body mass index (BMI) and triglyceride level than those without DM (P<0.05). Participants with DM and those without DM had similar PCI success rates (89.9% vs. 95.4%, respectively) and complete revascularization rates (82.8% vs. 84.1%, respectively). There were no significant differences between groups in the rates of all-cause mortality, cardiac death, major adverse cardiovascular events (MACEs), readmission, recurrence of angina, target vessel revascularization (TVR), or myocardial infarction (MI) during a median follow-up of 20.5 months. Multivariable logistic regression revealed that CTO in a coronary branch vessel was associated with higher odds of all-cause death (odds ratio (OR): 53.56; 95% confidence interval (CI): 2.48 to 1,155.41; P<0.05) and failure of PCI for CTO (OR: 5.40; 95% CI: 1.263 to 23.098; P<0.05). Additionally, PCI for single CTO was associated with lower odds of MACEs (OR: 0.300; 95% CI: 0.118 to 0.765; P<0.05). Conclusions: The performance of PCI for CTO has a high success rate in both patients with DM and those without DM, and clinical outcomes are comparable between groups.