A total of 1650 glutamic acid decarboxylase 65-kilodalton isoform (GAD65)-specific CD4(+) T cells were isolated and 1003 different TCRs were identified in the peripheral blood of 6 patients and 10 patients with type 1 diabetes mellitus who were positive for islet autoantibodies. This evidence concerns the gene GAD2 and type 1 diabetes mellitus.