The influence of insulin sensitivity and glucose tolerance on the effects of antiviral therapy for HCV remains unclear. The aim of the present study was (1) To elucidate the clinical and virological factors associated with sustained viral response in patients with combination therapy with PEG-IFN and ribavirin. (2) To clarify the influence of diabetes mellitus (DM), impaired glucose tolerance test (IGT) and insulin resistance (IR) on the HCV response to combination therapy with PEG-IFN and ribavirin. (3) To test the influence of combination therapy on HOMA IR