PDCD1 and type 1 diabetes mellitus: The importance of the PD-1/PD-L1 pathway in maintenance of immune tolerance toward pancreatic beta cells in humans is furtherly highlighted by the observation that 0.4–2.0% of individuals undergoing treatment with ICI (anti-PD-1 and/or anti-PD-L1 mAb) develop T1D (11–13).