ABSTRACT: OBJECTIVE:This study was conducted to determine the prevalence and genotype distribution of hepatitis C virus (HCV) infection among patients with type 2 diabetes mellitus (DM). SUBJECTS AND METHODS:We included 556 consecutive patients with confirmed type 2 DM attending the Diabetic Clinic of the Bushehr University of Medical Sciences and 733 nondiabetic subjects as controls. Serum levels of fasting blood sugar (FBS), alanine transaminase (ALT), aspartate transaminase (AST), total cholesterol (TCH), and triglycerides (TG) were measured by enzymatic colorimetric methods, and the presence of anti-HCV antibodies was determined by enzyme-linked immunosorbent assay. Semi-nested reverse transcriptase-polymerase chain reaction (RT-PCR) followed by sequencing was performed on all anti-HCV-seropositive samples. Data were analyzed using the Statistical Package for the Social Sciences 17, and descriptive statistics, ?2 test, Fisher exact test, and the Student t test were used for analysis. RESULTS:The seroprevalence of HCV in the diabetic patients was 1.98% (11/556), which was higher than HCV prevalence among the nondiabetic controls (4/733, 0.54%) (p = 0.032). No significant differences in ALT, AST, FBS, TG, and TCH levels were found between the HCV-seropositive and HCV-seronegative diabetic patients, although HCV-seropositive diabetic patients tended to have higher ALT, AST, and TCH levels, but lower TG and FBS levels than HCV-seronegative patients. In logistic regression analysis, only AST levels were significantly associated with HCV seropositivity among diabetic patients. The AST level of 41-80 IU/L was the only significant predictive variable for HCV seropositivity in the diabetic patients (odds ratio, 4.89; 95% CI: 1.06-22.49; p = 0.041). Of the 11 HCV-seropositive diabetic patients, 10 (91%) had HCV viremia with genotype 3a. CONCLUSION:Patients with type 2 DM had a higher prevalence of HCV infection than controls, and HCV seropositivity was independent of biochemical parameters.