Although the association between hepatitis C virus HCV infection and diabetes has been established the relationship between hepatitis B virus HBV infection and diabetes remains obscure. A new study published in the Journal of Viral Hepatitis compared the association between diabetes development in HBV HCV and co infected HBV HCV patients to that in non infected participants. This study used the National Health Insurance Service National Sample Cohort comprising 514 791 randomly selected individuals aged between 40 and 79 years who underwent health check ups from 2002 to 2003. Subjects without a prior history of diabetes who were found to have HBV or HCV infection from 2002 to 2003 were recruited. The results revealed that the cumulative incidences incidence densities and hazards ratios HRs of diabetes were highest in the co infected group followed by those in the HCV HBV and non infected groups. The 12 year cumulative incidences were 42.0 in HBV HCV 32.9 in HCV 23.9 in HBV and 18.3 in the non infected groups. The incidence density per 1 000 person years was 55.0 51.5 38.2 and 28.2 for the HBV HCV HCV HBV and non infected groups respectively. While the adjusted HRs for diabetes were 1.90 1.68 and 1.41 for the HBV HCV HCV and HBV infected groups respectively. From the findings it was inferred that both HCV and HBV infections are associated with the development of diabetes. Thus it was stated that prevention screening and treatment of both may reduce the risk of diabetes in these patients.