INS and autoimmune disease: Many receptors, enzymes and hormones have been identified as target antigens for organ-specific autoimmune diseases, providing a large basis for the diagnosis of APS.[4] Currently, islet-specific autoantibodies include glutamic acid decarboxylase antibody (GADAb), protein tyrosine phosphatase antibody (IAA-2), anti-islet cell antibody (ICA), anti-insulin antibody and anti-zinc transporter 8 antibody.