HLA-DRB1 and type 1 diabetes mellitus: HLA-DR3 genes; DRB1*0301, DQB1*0201 and DQB1*0302 and DQA1*0301 and DQA1*0501 were significantly increased in the IDDM compared to the control participants. HLA-DR4 gene DRB1*0405 was also significantly higher in the IDDM compared to the control participants.