CD274 and diabetes mellitus: The most frequent endocrine adverse effect linked to anti-PD-1 therapy is primary thyroid dysfunction, while there are a few rare cases of type 1 diabetes mellitus reported.[2] Sintilimab is a fully human IgG4 monoclonal antibody that binds to programmed cell death receptor-1 (PD-1), thereby blocking the interaction of PD-1 with its ligands (PD-L1 and PD-L2) and it thus restores T cell activation and proliferation and consequently induces an anti-tumor immune response.[3] This blockage causes a decrease in peripheral immune tolerance, which leads to T lymphocyte autoimmune clone activation.