Clinical features, diagnosis and prognosis of nivolumab-associated fulminant type 1 diabetes.

Fulminant type 1 diabetes (FT1D) is a rare immune-related adverse event associated with nivolumab, and its clinical characteristics remain unclear. This study aims to characterize the clinical features of nivolumab-associated FT1D and to generate evidence to inform its diagnosis and prevention. A systematic search of databases was conducted to identify clinical cases of nivolumab-associated FT1D reported through March 31, 2026. Clinical data for the patients were extracted and subjected to statistical analysis. A total of 59 patients were included, with a median age of 59 years (range 22, 87). The median time to onset of FT1D was 90 days (range 9, 1988) after the initial administration of nivolumab, with a median treatment cycle of 6 cycles (range 1, 136). Polyuria (45.1%), polydipsia (31.4%), weight loss (29.4%), thirst (23.5%), nausea (23.5%), vomiting (21.6%), and fatigue (19.6%) were the main symptoms. The median plasma glucose level at the diagnosis of FT1D was 594 mg/dL (range 208.8, 1652.4), and the median HbA1c was 7.2% (range 5.4, 8.9). Glutamic acid decarboxylase antibody positivity was detected in 23.6% of patients. Following nivolumab discontinuation and initiation of intensive insulin therapy, glycemic control was satisfactorily achieved. FT1D is a rare immune-related adverse event associated with nivolumab. Close plasma glucose monitoring should be maintained both during nivolumab therapy and after drug discontinuation. The possibility of FT1D should be considered in patients presenting with hyperglycemic symptoms and diabetic ketoacidosis. Nivolumab-associated FT1D requires long-term maintenance insulin therapy.