Vnitr Lek 2025, 71(8):498-501

Immune-mediated diabetes mellitus induced by checkpoint inhibitors: case reports and clinical overview for internists

Martina Tuháčková, Jan Brož

Interní klinika, 2. LF UK a FN Motol, Praha

Immune checkpoint inhibitors (ICIs) represent a major advancement in the treatment of solid tumors, but their use carries the risk of immune-related adverse events (irAEs). Among the rare but clinically significant irAEs is insulin-dependent diabetes mellitus (ICI-DM), which shares features with type 1 diabetes. This article presents two case reports of patients who developed ICI-DM during anti-PD-1 therapy (nivolumab, pembrolizumab). The first case involved acute onset of ICI-DM with diabetic ketoacidosis, positive autoantibodies, and concurrent autoimmune hepatitis. The second patient, with pre-existing type 2 diabetes, initially presented with hyperglycemia; however, a rapid decline in C-peptide levels later confirmed β-cell autoimmune destruction. The discussion summarizes current knowledge of the pathogenesis, clinical course, and management of ICI-DM, emphasizing the importance of monitoring C-peptide and blood glucose during immunotherapy.

Keywords: checkpoint inhibitors, immune-related adverse events, type 1 diabetes mellitus, ICI-DM, immunotherapy, autoimmune toxicity.

Accepted: November 26, 2025; Published: December 15, 2025  Show citation