T1D-associated islet antigens include GAD65 [8], [22], [23], (prepro)insulin (PPI) [24], [25], [26], insulinoma associated-2 (IA-2) [27], islet-specific glucose-6-phosphate catalytic subunit-related protein (IGRP) [28], [29], and zinc transporter-8 (ZnT8) [30]. Here, G6PC2 is linked to type 1 diabetes mellitus.