This study confirms in Italian population the strong association between T1DM and the DR3DQ2 and DR4DQ8 haplotypes, already known to confer high risk, and confirmed the protective role of the haplotype DRB1 * 15: 01-DQA1 * 03-DQB1 * 06: 02. This evidence concerns the gene HLA-DQA1 and type 1 diabetes mellitus.