In 2003, Ansari et al. demonstrated in prediabetic non-obese diabetic (NOD) mice (used as an animal model for T1DM as they develop diabetes following insulitis) that PD-1 or PD-L1 blockade rapidly precipitated diabetes, which was not the case with PD-L2 blockade. Here, PDCD1LG2 is linked to type 1 diabetes mellitus.