GAD1 and type 1 diabetes mellitus: The loss of self-tolerance leading to T1D in NOD mice has been substantiated by the identification of at least 18 islet antigens targeted by CD4+ and CD8+ T cells, including insulin, glutamate glutamic acid decarboxylase (GAD), the protein tyrosine phosphatase-like IA-2, islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGPR) and heat shock protein 60 (HSP60) (Babad et al., 2010; James et al., 2020).