Although the exact incidence of IFNα-induced diabetes is unknown, several large retrospective studies investigating adverse effects of IFNα in patients with chronic viral hepatitis, mainly hepatitis C, reported incidences of 0.08% (10/11.241) (105) in Italy, and 0.7 (5/667)–0.96% (12/1.250) in Japan (106, 107). This evidence concerns the gene IFNA1 and diabetes mellitus.