Several studies found hepatitis C (HCV) increases risk of Type II diabetes mellitus (DM). However, others found no or only sub-group specific excess risk. We performed meta-analyses to examine whether HCV infection does increase DM risk in comparison to the general population and in other sub-groups with increased liver disease rates including with hepatitis B (HBV). We followed standard guidelines for performance of meta-analyses. Two independent investigators identified eligible studies through structured keyword searches in relevant databases including PubMed. We identified 34 eligible studies. Pooled estimators indicated significant DM risk in HCV-infected cases in comparison to non-infected controls in both retrospective (OR(adjusted)=1.68, 95% CI 1.15-2.20) and prospective studies (HR(adjusted)=1.67, 95% CI 1.28-2.06). Excess risk was also observed in comparison to HBV-infected controls (OR(adjusted)=1.80, 95% CI 1.20-1.40) with suggestive excess observed in HCV+/HIV+ cases in comparison to HIV+ controls (OR(unadjusted)=1.82, 95% CI 1.27-2.38). Our finding of excess DM risk with HCV infection in comparison to non-infected controls is strengthened by consistency of results from both prospective and retrospective studies. The excess risk observed in comparison to HBV-infected controls suggests a potential direct viral role in promoting DM risk, but this needs to be further examined.
