New-onset type 1 diabetes mellitus as a delayed immune-related event after discontinuation of nivolumab: A case report.

rationaleImmune checkpoint inhibitors (ICIs) have revolutionized cancer treatment. However, they may cause immune-related adverse events. Although there have been a few reports of new-onset type 1 diabetes mellitus (T1DM) during ICI treatment, T1DM as a delayed immune-related event after discontinuing immunotherapy is extremely rare. Herein, we report the case of an elderly veteran who presented with diabetic ketoacidosis 4 months after the discontinuation of treatment with nivolumab. PATIENT CONCERNS: A 74-year-old veteran was treated with second-line nivolumab for advanced non-small cell lung cancer. After 9 treatment cycles, the administration was discontinued due to fatigue. Four months later, he was admitted to the emergency department in a stuporous mental state and hyperglycemia, with high glycosylated hemoglobin levels (10.6%). C-peptide levels were significantly decreased, with negative islet autoantibodies. DIAGNOSES: We diagnosed nivolumab-induced T1DM. There were no laboratory results indicating a new thyroid dysfunction or adrenal insufficiency, which are typical endocrine adverse reactions.

interventionsSince the hypothalamic and pituitary functions were preserved and only the pancreatic endocrine capacity was impaired, we administered continuous intravenous insulin injections, with fluid and electrolyte replacement. OUTCOMES: His serum glucose levels decreased, and symptoms improved; hence, on the 8 day of hospitalization, we switched to multiple daily insulin injections. LESSONS: The present case indicates that regular glucose monitoring and patient education are needed for diabetic ketoacidosis after the discontinuation of ICI therapy.