The difference in HLA-DRB1 genotype distribution between MODY and type 1 diabetes is especially remarkable when patients carry two risk alleles (5.4% MODY vs. 48.1% type 1 diabetes) or none (64.9% MODY vs. 7.5% type 1 diabetes). This evidence concerns the gene HLA-DRB1 and type 1 diabetes mellitus.