Background: Plasma selenium (Se) concentrations corresponding to optimal health are highly dynamic and based on a combination of factors that need to be considered when assessing epidemiological data, such as the findings linking serum Se and type 2 diabetes mellitus (DM). High serum Se concentrations may be associated with a higher occurrence of diabetes. Aim: Toevaluate the correlations between serum Se levels and DM in patients with chronic Hepatitis C (CHC). Patients and Methods:This case-control studyincluded three groups; group 1 (29 CHC patients with DM), group 2 (29 CHC patients without DM) and group 3 (29 healthy control). Subjects were tested for biochemical liver function tests, fasting blood sugar [FBS], and fasting insulin levels). Homeostasis model assessment (HOMA)-insulin resistance (IR) was calculated. Se levels were measured using Atomic Absorption Spectroscopy. Results: serum Se were significantly higher in group 1 and group 3 compared to group 2 (p<0.01). Meanwhile, serum Se were insignificantly higher in group 1 than in group 3 (p>0.05). Cutoff value to differentiate diabetic and non-diabetic CHC patients using serum Se was >10 µg/l with sensitivity (76%) and, specificity (86.2%). The incidence and the risk of Se deficiency were significantly higher among group 2 than among group 2 (24.1% vs. 3.4%, respectively) (p<0.05). In entire CHC patients (group 1+group 2), the mean HOMA-IR values were significantly lower in the group with deficient Se levels than in the group with normal Se levels (p=0.005). A negative correlations between serum Se levels and ALT levels, AST levels, and diabetes treatment was found. Conclusions: Serum Se levels were significantly higher in CHC+DM group and in control group than in CHC group. The incidence and the risk of Se deficiency were higher among HCV group compared to CHC+DM group.