Consequently, his anti-glutamic acid decarboxylase (anti-GAD) and anti-tyrosine phosphatase-like insulinoma antigen 2 (anti-IA2) antibodies were checked; both were positive (anti-GAD > 2000 [+], Anti-IA2 47.8 [+]) and T1DM was diagnosed as a result. This evidence concerns the gene GAD1 and type 1 diabetes mellitus.