Analysis of insulitis scores of the Idd strains revealed that NOD congenics that were partially (Idd 9.2, Idd 3/10/18) or fully (Idd3/5) protected from anti PDL1 accelerated diabetes had lower basal insulitis scores (Idd 9.2 (0.18±0.11), Idd3/10/18 (0.24±0.059) and Idd3/5 (0.0±0.0) compared to the almost unprotected Idd9.1 (1.2±0.3), Idd9.3 (0.82±0.14) and the NOD (1.23±0.24) mice. Here, CD274 is linked to diabetes mellitus.