Background and study aim:: The highest Hepatitis C Virus (HCV) prevalence in the world occurs in Egypt. The frequency of type 2 diabetes mellitus tends to be high in patients infected with HCV especially those with cirrhosis. We conducted this study to define the prevalence and predictors of diabetes mellitus (DM) in chronic hepatitis C patients with and without liver cirrhosis. Patients and methods:  Four hundred patients with HCV were enrolled (200 without cirrhosis [group I] and 200 with cirrhosis [group II]).Two hundred non hepatic disease subjects were enrolled as a control group [group III]. All patients were subjected to thorough history taking and physical examination. Investigations include liver function tests, viral markers (anti-HCV anti-bodies and polymerase chain reaction (PCR) for HCV), liver biopsy and abdominal ultrasound. Multiple logistic regression analysis was used to adjust for potential confounders. Results :Prevalence of Type 2 diabetes was 30.25% in HCV patients as opposed to only 6.5 % of control group (p <0.0001, odds ratio [OR] = 2.7).Moreover the prevalence is significantly higher in HCV patients with cirrhosis than in non cirrhotic patients (51% vs. 9.5%), (OR= 9.9, P < 0.001). Partial correlation of prevalence of diabetes mellitus in HCV patients remain highly significant after adjustment for age, sex, family history of diabetes and BMI (r=0.291, P< 0.0001). Using logistic regression; older age, positive family history of diabetes, higher BMI, lower serum albumin level, higher activity and fibrosis score ( OR= 1.3,19.4,1.8, 6.6,1.3 and 2.1 respectively) in patients with chronic hepatitis C were found to be associated with higher prevalence of DM (P <0.05), while activity by fibrosis was insignificant. Conclusion : Chronic HCV is associated with increased risk of diabetes to 2.7-fold.Development of cirrhosis in patients with chronic HCV increases risk of diabetes to 10-folds. This association seems not to be related to the known risk factors for diabetes. Potential predictors for this association might include older age, positive family history of diabetes, higher BMI, lower serum albumin level, higher activity and fibrosis score.