Matched population-based study examining the risk of type 2 diabetes in people with and without diagnosed hepatitis C virus infection.

Meta-analyses have found hepatitis C virus (HCV) infection to be associated with an increased risk of type 2 diabetes mellitus (T2DM). Here, we examine this association within a large population-based study, according to HCV RNA status. A data-linkage approach was used to examine the excess risk of diagnosed T2DM in people diagnosed with antibodies to HCV (anti-HCV) in Scotland (21 929 anti-HCV(+ves) ; involving 15 827 HCV RNA(+ves) , 3927 HCV RNA(-ves) and 2175 with unknown RNA-status) compared to that of a threefold larger general population sample matched for gender, age and postcode (65 074 anti-HCV(-ves) ). To investigate effects of ascertainment bias the following periods were studied: up to 1 year before (pre-HCV)/within 1 year of (peri-HCV)/more than 1 year post (post-HCV) the date of HCV-diagnosis. T2DM had been diagnosed in 2.9% of anti-HCV(+ves) (including 3.2% of HCV RNA(+ves) and 2.3% of HCV RNA(-ves) ) and 2.7% of anti-HCV(-ves) . A higher proportion of T2DM was diagnosed in the peri-HCV period (i.e. around the time of HCV-diagnosis) for the anti-HCV(+ves) (22%) compared to anti-HCV(-ves) (10%). In both the pre-HCV and post-HCV periods, only those anti-HCV(+ves) living in less deprived areas (13% of the cohort) were found to have a significant excess risk of T2DM compared to anti-HCV(-ves) (adjusted odds ratio in the pre-HCV period: 4.0 for females and 2.3 for males; adjusted hazard ratio in the post-HCV period: 1.5). These findings were similarly observed for both HCV RNA(+ves) (chronic) and HCV RNA(-ves) (resolved). In the largest study of T2DM among chronic HCV-infected individuals to date, there was no evidence to indicate that infection conveyed an appreciable excess risk of T2DM at the population level.