Hepatitis C virus (HCV) causes extrahepatic manifestations as well as liver diseases, and contributes to insulin resistance and type 2 diabetes mellitus. The purpose of the present study was to evaluate the relationship of extrahepatic manifestations and insulin resistance in an HCV hyperendemic area. We investigated the incidence of extrahepatic manifestations among 139 inhabitants living in an HCV hyperendemic area in 2002 and compared it to 1999 data for the same inhabitants. Insulin resistance was tested for some non-HCV or HCV-infected inhabitants we had identified during mass screenings in 1999 and 2002. For some of the inhabitants in 2002, we examined records on the prevalence of insulin resistance seven years earlier. The prevalence of extrahepatic manifestations among individuals with positivity for anti-HCV antibodies was higher than among those without HCV in both 1999 and 2002. The prevalence of each extrahepatic manifestation which we identified in 2002 was higher than in 1999. Moreover, in some non-HCV or HCV-infected inhabitants, insulin resistance in 2002 was significantly higher than in 1999. Among inhabitants who had HCV infection with extrahepatic manifestations, fasting insulin levels or HOMA-IR findings seven years prior was significantly higher than for inhabitants who had neither HCV infection nor extrahepatic manifestations (p = 0.03, p = 0.01, respectively). Insulin resistance induces HCV infection, which causes an increase in the incidence of extrahepatic manifestations in HCV-infected individuals.