CTLA4 and diabetic ketoacidosis: MOA: mechanism of action; ICI: immune checkpoint inhibitors; PD-L1: programmed death-ligand 1; CTLA-4: cytotoxic T-lymphocyte-associated antigen-4; MEK: mitogen-activated protein kinase; DKA: diabetic ketoacidosis; HbA1C: glycated hemoglobin