GAD2 and type 1 diabetes mellitus: During the period preceding T1D clinical onset, autoantibodies (aAbs) directed to islets antigens such as insulin, glutamic acid decarboxylase (GAD65), insulinoma associated protein-2 and zinc transporter 8 (Znt8) may be detectable for months up to years before disease onset [2], and progressively wane after diagnosis [3].