GAD1 and type 1 diabetes mellitus: Following this, three additional autoantibodies were discovered to aid in screening, analysis, and prediction of T1D: GAD autoantibodies (GADA), discovered in 1990 (7), tyrosine phosphatase-like protein IA-2 autoantibodies (IA-2A), discovered in 1994 (8), and zinc transporter 8 autoantibodies (ZnT8A), discovered in 2007 (9).