GAD2 and type 1 diabetes mellitus: Autoantibodies play a role in T1D, as in other autoimmune diseases (6, 7) The major islet- autoantibodies are against insulin (IA), L-Glutamic acid decarboxylase 65 (GAD65), Protein tyrosine phosphatase like protein (IA-2), and the β -cell zinc transporter (ZnT8) (8, 9).