Background: Both human immunodeficiency virus (HIV) and hepatitis C virus (HCV) infections have been reportedly associated with a higher risk of diabetes mellitus (DM) but results are conflicting. Aims: To determine whether there is an association between chronic HCV and the incidence of DM, and to study the role of factors such as cirrhosis, IFN-based HCV therapy, sustained virologic response (SVR) and chronic HBV infection among patients living with HIV (PLHIV) followed in a large French multicentre cohort in the combination antiretroviral therapy (cART) era. Methods: All PLHIV followed up in the Dat'AIDS cohort were eligible. Cox models for survival analysis were used to study the time to occurrence of DM. Results: Among 28 699 PLHIV, 4004 patients had chronic HCV infection. The mean duration of HCV follow-up was 12.5 ± 8.1 years. The rate ratio of DM was 2.74 per 1000 person-years. By multivariate analysis, increasing age, body mass index>25, AIDS status, nadir CD4 cell count ≤200/mm3 , detectable HIV viral load and cirrhosis (HR 2.26 95% CI 1.14-1.18; P < 0.0001) were predictors of DM, whereas longer cART duration was associated with a lower risk of DM. Chronic HCV and HBV infection and IFN-based HCV therapy were not associated with DM. In a subanalysis among HCV-infected patients, SVR was not related to DM. Conclusions: Our study shows that in the HIV population, cirrhosis is associated with an increased occurrence of DM, but not chronic HCV infection or duration of HCV infection.