Incidence of diabetes mellitus in patients treated with immune checkpoint inhibitors (ICI) therapy-A comprehensive cancer center experience

Background: Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment and more patients are receiving ICIs than before. Although this has improved cancer care but so has the increase in the incidence of immune-related adverse events (irAEs) including endocrinopathies. ICI-induced diabetes mellitus (DM) is a rare irAE with an approximate incidence of 1%. Due to paucity of data in literature about ICI-induced DM, we conducted a study to report the incidence and characteristics of new onset and worsening of DM in patients treated with ICIs. Methods: We conducted a retrospective review of patients who received ICIs during 10-year period. We identified patients with newly diagnosed DM and worsening of preexisting DM. Findings: Among 2,477 patients who received one or multiple ICIs, 14 patients developed new onset DM and 11 patients experienced worsening of pre-existing DM. Median time to new onset or worsening DM from ICI treatment initiation was similar to 12 weeks. Median hemoglobin A1c was 6.2% at baseline and 8.5% at the onset of ICIinduced DM. Seven patients presented with diabetes ketoacidosis (DKA), all in the new onset group. (p = 0.02) No significant difference was observed between two groups regarding personal history of autoimmune disorder or family history of DM. (p greater than 0.05) Positive autoantibodies were found in three patients [two with Glutamic Acid Decarboxylase (GAD65) antibodies and one with insulin autoantibodies (IAA)]. Interpretation: The incidence of new onset and worsening DM in patients treated with ICIs was 1.01%.