2022 Volume 65 Issue 12 Pages 672-679
A 53-year-old man visited our hospital because of severe appetite loss, thirst, and nausea. He had been receiving treatment for type 2 diabetes mellitus for the past nine years and had also been receiving pembrolizumab therapy as second-line treatment for ureter cancer for the past three months. Severe hyperglycemia, insulin secretion deficiency (fasting plasma C-peptide, 0.3 ng/mL), and ketosis after pembrolizumab administration led to the diagnosis of pembrolizumab-induced type 1 diabetes mellitus. Even two years after the onset of type 1 diabetes mellitus, his insulin secretion remained decreased. Several cases of programmed death receptor-1 (PD-1) antibody-induced type 1 diabetes mellitus in patients with type 2 diabetes mellitus have been reported. Previous case reports revealed that the HbA1c value at the diagnosis in PD-1 antibody-induced type 1 diabetes mellitus that developed from type 2 diabetes mellitus was higher than X, and all reported cases were in men. Immune checkpoint inhibitors, including PD-1 antibody, are widely used for advanced malignancy treatment in patients with type 2 diabetes mellitus. Clinicians should thus carefully monitor patients for ketosis or ketoacidosis-related symptoms, glycemic control, and endogenous insulin secretion when administering PD-1 antibody therapy, even in those who already have type 2 diabetes mellitus.
