HLA-DRB1 and type 1 diabetes mellitus: Insulin is an important autoantigen in type 1 diabetes (T1D) autoimmunity, most likely the primary causative antigen in the spontaneously diabetic NOD mouse, and a target autoantigen in Caucasian individuals with the highest HLA-DRB1*04, DQ8 risk-haplotype [1]–[3].