Serologic case-control studies have suggested an association between coxsasckie group B viruses and insulin-dependent diabetes mellitus (IDDM). New investigations have identified enteroviral nucleic acid in the peripheral blood mononuclear cells of newly-diagnosed patients with IDDM. The disease pathogenesis is dependent on several factors. including the genetics of the host, strain of virus, activation status of autoreactive T-cells, upregulation of pancreatic MHC-1 antigens, molecular mimicry between viral and beta cell epitopes and direct islet cell destruction by viral cytolysis. Epitopes (IDDM-E1 and E2) on glutamate decarboxylase 65 (GAD65) are the most common targets for antibody and cellular-mediated autoimmune beta cell destruction.