GAD1 and diabetes mellitus: It has been reported that approximately 42 − 50% of patients with ICI-DM have at least one positive autoantibody, including anti-GAD, anti-IA-2, anti-ZnT8, or IAA [7, 16, 25]; however, the positive rate appears to be much lower than that of classical T1DM, where GAD-Ab is positive at diagnosis in 80% of cases [9, 10].