Development of insulin-dependent diabetes mellitus in a patient with chronic hepatitis C during therapy with...

Interferon (IFN)-alpha is used for the treatment of chronic viral hepatitis. It has been associated with various forms of autoimmune disease, e.g. autoimmune hepatitis, Hashimoto thyroiditis and insulin-dependent diabetes mellitus. Further, an increase of insulin resistance and development of non-insulin-dependent diabetes mellitus has been described after treatment with IFN-alpha. Several studies have investigated the induction of different autoimmune markers by IFN-alpha, but only few specified patients who developed insulin-dependent diabetes mellitus. We report the case of a 37-year-old man with chronic hepatitis C who was treated with IFN-alpha plus ribavirin. Thirty weeks after the start of treatment, the patient developed insulin-dependent diabetes mellitus and therapy was withdrawn. HLA typing showed an HLA-DR1,3 phenotype. At manifestation of diabetes mellitus, the C-peptide level was 0.37 ng/ml (normal range 0.5-3 ng/ml). The patient had a positive family history for type 2 diabetes. Several autoimmune markers were investigated before, during and 6 months after withdrawal of antiviral treatment. High titres of glutamic acid decarboxylase (GAD) antibodies were present before therapy. A significant increase in titres of islet cell antibodies, parietal cell antibodies and sperm antibodies was present after 14 weeks of IFN-alpha treatment. Six months after withdrawal of IFN-alpha therapy, these antibodies had significantly decreased whereas GAD antibodies remained unchanged. There was no clinical sign of any other autoimmune disease. Our data show that, in patients with a predisposition to insulin-dependent diabetes mellitus, the disease may become manifest as a side-effect during therapy with IFN-alpha. Several pathogenetic factors may be involved in this process, and, in addition to IFN-alpha, hepatitis C itself may induce autoimmune mechanisms. We conclude that screening for autoantibodies specific for type 1 diabetes should be performed before the start of IFN-alpha treatment. In patients found to be at increased risk of developing diabetes mellitus type 1, monitoring of titres of these antibodies during therapy could help to assess the individual risk-benefit ratio of IFN-alpha treatment.