HLA-DRB1 and type 1 diabetes mellitus: Regarding the genotype frequencies, HLA-DRB1*01/04, *03/03, *03/04 and *04/13 were significantly more frequent in patients, HLA-DRB1*03/03 presented the largest OR, and HLA-DRB1*03/04 was the most common genotype among T1D patients.