Compared to T1D, the susceptible DR3 and DR9 haplotypes were less frequent, whereas the protective haplotypes (DRB1*1101-DQA1*05-DQB1*0301 and DRB1*1202-DQA1*0601-DQB1*0301) were more frequent in ICI-DM patients. Here, HLA-DQA1 is linked to type 1 diabetes mellitus.