THU378 Presentation Of Autoimmune Destruction Of Pancreatic Beta Cells By Pembrolizumab In The Setting Of Existing Type 2 Diabetes

Disclosure: J. Seidenberg: None. M.J. Ansari: None. Background: Prembrolizumab, like other immunotherapies, have become a commonplace treatment for certain cancers. Its method of action is binding of the programmed cell death I receptor that blocks the binding of the programmed cell death ligand 1. PD1-1 receptors have been reported to cause autoimmune endocrinopathies including type 1 diabetes. Many patients who present with the adverse reaction of autoimmune diabetes type 1 present with ketoacidosis. However, patients already diagnosed with diabetes type 2 on insulin could have this strong initial presentation masked. Clinical Case: Patient is a 76 year old female who was recently diagnosed with bladder cancer and started on Pembrolizumab. She presented to the endocrinology clinic due to new onset poor blood sugar control with self-tested glucose levels ranging from 300-400. This patient was previously diagnosed with diabetes type II and was taking metformin, Levemir 18 units daily, Humalog 6 units AC. A C peptide level was obtained during euglycemia, which was undetectable, indicating autoimmune destruction of pancreas. Patient was continued on Pembrolizumab due to her clinical response to it and a low probability of pancreatic beta cells functioning again. Patient’s C peptide continued to be undetectable 1 year after her presentation. Conclusion: Autoimmune destruction of pancreatic beta cells from Pembrolizumab is a rare but important adverse effect. Pembrolizumab has been reported to be associated with autoimmune-related pancreatitis leading to type 1 diabetes in only 0.1% of all patients in clinical trials. We present this patient, who was already being treated with insulin for type 2 diabetes and thus was being tested for elevated glucose regularly. She was able to notice a significant change in glucose control prior to onset of symptoms. All patients who take Pembrolizumab, especially those with underlying diabetes, should be regularly evaluated for interference with pancreatic beta cells with regular glucose labs and if hyperglycemia occurs, with a C peptide level should then be ordered. Presentation: Thursday, June 15, 2023