GAD1 and diabetes mellitus: Stamatoulo et al. found that among three patients with ICI-DM, one had islet autoantibodies prior to ICI-DM, another had seroconversion from negative to positive after the initiation of ICI therapy, while the other patient remained negative for anti-GAD, anti-IA2 and anti-ZnT8 before and after the onset of ICI-DM [27].