OBJECTIVES: The influence of glucose abnormalities on the efficacy of antiviral treatment is unknown. This study investigated whether glucose abnormalities (impaired fasting glucose and type 2 diabetes) influence the response to antiviral therapy with interferon plus ribavirin in patients with chronic hepatitis C. METHODS: A total of 178 treatment-naïve patients with chronic hepatitis C treated with combination therapy were retrospectively studied. SVR was assessed after completing treatment. Fasting plasmatic glucose was measured prior to therapy. RESULTS: Compared with nonresponders (N = 111), patients with SVR (N = 67) had lower plasma glucose (94.1 ± 12.7 vs 104.4 ± 25.8 mg/dL, P = 0.001) and a lower prevalence of glucose abnormalities (24.24% vs 44.14%, P = 0.012). The SVR rate was 45.13% in patients with normoglycemia (N = 113), 28.26% in patients with impaired fasting glucose (N = 46), and 15.78% in type 2 diabetic patients (N = 19) (P < 0.001). Multivariate logistic regression identified genotype 1 (OR 1.55, 95% CI 1.01-2.41, P = 0.05), γ-glutamyltranspeptidase level (OR 6.41, 95% CI 1.86-22.07, P = 0.003), and presence of glucose abnormalities (OR 2.33, 95% CI 1.04-5.20, P = 0.039) as being independently associated with the absence of an SVR. In addition, patients with glucose abnormalities (N = 65) showed a lower virological response rate when compared with a subgroup of normoglycemic patients (N = 65) matched for sex, age, and liver fibrosis (24.6% vs 44.6%, P = 0.001). CONCLUSIONS: Glucose abnormalities are an independent predictor of poor virological response to combined therapy in hepatitis C virus infected patients. © 2007 by Am. Coll. of Gastroenterology.