6779 The Diversity of Immune Checkpoint Inhibitor Associated Diabetes

Abstract Disclosure: V.A. Mendpara: None. M. Lansang: None. M. Caromori: None. L. Kennedy: None. K. Zhou: None. Immune checkpoint inhibitor (ICI) treatment has become a first-line therapy for a variety of cancers, including use of nivolumab (a programmed death 1 PD-1 inhibitor) for metastatic melanoma. Though able to prolong survival, ICIs cause immune-related adverse events (irAE) through down-regulation of immune control pathways. One irAE is diabetes mellitus (DM), referred to as ICI-induced DM. Despite its low incidence (2%), ICI-induced DM carries with it high morbidity, with need for hospitalization in up to 25% of patients, and burden as patients are typically committed to multiple daily insulin injections (MDII). Here we report diverse presentations of four patients treated with ICI for metastatic melanoma who developed ICI-induced DM. The median age at DM presentation was 60.5 years (range 59-78 years). All patients received nivolumab and one patient was also treated with ipilimumab (a cytotoxic T-lymphocyte-associated antigen 4 inhibitor). The median time from start of ICI to development of ICI-induced DM was 32.5 wks, ranging from 27-46 wks. Three of the 4 patients previously developed hypothyroidism at median of 15 wks from starting ICI. Two patients presented in DKA and the other 2 with severe hyperglycemia (glucose 300 mg/dL). Median HbA1c was 7.05% (range 6.4%-7.4%) at presentation. GAD Ab was negative in 3 of 4 patients, including one who had DKA. C-peptide was undetectable (0.2 ng/mL) in the 2 patients with DKA, 0.4 ng/mL in one other patient, and not measured in the fourth. All patients were immediately started on MDII. However, the two patients without DKA on presentation were eventually initiated on non-insulin agents. One of them was started on a DPP-4 inhibitor and discontinued fast-acting insulin, and the other started a GLP-1 receptor agonist and reduced their fast-acting insulin requirement. The heterogeneity of DM presentation and its clinical course reported here highlights a few important points. The first is that the onset of ICI-induced DM is often much later than that of the most common endocrine irAE, hypothyroidism, which has an onset around 10 weeks in average. Second, DM often presents as severe hyperglycemia incidentally detected on blood work. GAD Ab positivity is relatively less common, suggesting a different underlying etiology than classic type 1 DM. Onset of severe hyperglycemia can occur over many weeks (as indicated by higher HbA1c), making it important to monitor for hyperglycemia in those with no previous history of prediabetes or DM. Finally, it may be possible to use a combination of non-insulin antihyperglycemic agents to provide better glycemic management. No widely validated strategies for the surveillance of irAEs are currently available, and a better understanding in the propensity of patients to develop irAEs is clearly required. Importantly, optimal management of irAEs relies on early recognition and frequently demands a multidisciplinary approach. Presentation: 6/2/2024