Aim: Diabetes mellitus (DM) is a potential risk factor for hepatocarcinogenesis, especially in patients with hepatitis C virus (HCV) infection. We aimed to elucidate whether DM influences the surgical outcomes of patients with hepatocellular carcinoma (HCC).Methods: Our patients were routinely controlled to keep urinary glucose excretion to less than 3.0 g/day before surgery, and the serum glucose level under 200 mg/dL after surgery. The surgical outcomes and postoperative complications of 112 patients with HCV-related HCC with DM (DM group) were compared to those of 112 propensity-matched patients without DM (non-DM group).Results: After a median follow-up of 3.2 years (range, 0.2-11.3 years), the median overall (5.2 years; 95% confidence interval, 3.8-6.5 years) and recurrence-free survival (2.2 years; 1.7-2.9 years) in the DM group were not significantly different from those (6.3 years; 5.4-7.1 years, P = 0.337; and 2.2 years; 1.7-3.6 years, P = 0.613) in the non-DM group. The independent factors related to overall survival were the background liver (hazard ratio, 2.06; 95% confidence interval, 1.27-3.39, P = 0.014) and tumor differentiation grade (2.07; 1.14-4.05, P = 0.015). Thirty-two patients (28.5%) in the DM group and 32 patients (28.5%) in the non-DM group had morbidities after operation, with no significant difference between the groups (P = 1.000). Furthermore, postoperative control status of DM did not affect the prognostic outcome.Conclusion: Diabetes mellitus does not affect the surgical outcomes of patients with HCV-related HCC, and it is not an unfavorable factor when selecting candidates for liver resection of HCC.