CD4 and type 1 diabetes mellitus: The PD-1/PD-L1 axis is fundamental in maintaining immune homeostasis and preventing organ-specific autoimmune diseases, such as T1DM.[10] The role of immune checkpoints in the pathophysiology of diabetes mellitus has been investigated in nonobese diabetic mice and in humans.[10] As PD-1 interaction with its ligands, PD-L1 and PD-L2, is crucial for regulating CD4/CD8 autoreactive T cells in transgenic mice, PD-L1 expression is associated with resistance to the precipitation of autoimmune diabetes.