In European ancestry populations, HLA-DRB1 haplotypes DRB1*03:01-DQA1*05:01-DQB1*02:01 and DRB1*04-DQA1*03:01-DQB1*03:02 provide the highest risk of developing diabetes, especially when both haplotypes are present in heterozygosis (7, 8). This evidence concerns the gene HLA-DRB1 and diabetes mellitus.