Biomarkers that predict type 1 diabetes (T1D) are unreliable for CIADM.AIMIn the present study, we sought to identify biomarkers for the prediction of CIADM.METHODSFrom our prospective biobank, we identified 14 patients with CIADM who had metastatic melanoma treated with anti-programed antibody death 1 (anti-PD-1) with or without anti-cytotoxic T lymphocyte-associated antibody protein 4 (anti-CTLA4). This evidence concerns the gene CTLA4 and type 1 diabetes mellitus.