Prior to this, T1DM following ICI therapy was reported to be rare – (a) diabetes was not reported in a 2016 meta-analysis [198] (b) reported as 0.2–0.9% after anti-PD-1 and 0.1–0.3% after anti-PD-L1 therapy in 2017 [195], and (c) only 13 cases (0.2%) in the 2018 systematic review and meta-analysis [199]. Here, PDCD1 is linked to type 1 diabetes mellitus.