Both HLA-DRB1*15:01 and HLA-DRB1*15:03 were less protective for Type 1 diabetes in our African American samples [odds ratio 0.36 (95% CI 0.11–1.11), odds ratio 0.39, 95% CI 0.19–0.80)] than HLA-DRB1*15:01 in Europeans (odds ratio 0.05, 95% CI 0.04–0.07; Supporting Information, Table S1). Here, HLA-DRB1 is linked to type 1 diabetes mellitus.