PDCD1 and diabetes mellitus: Expenditure on ICIs thus accounted for 40% of the total increase in Medicare Part B drug spending over this time period.[1] This global rise in ICI (PD-1 antibodies) use has led to greater recognition of immune-related adverse events (irAEs), including rare but serious endocrinopathies such as ICI-induced type 1 diabetes mellitus (ICI-T1DM).[2]