2020 Volume 63 Issue 8 Pages 521-527
A 72-year-old man was hospitalized because of diarrhea, anorexia, and motion difficulty that occurred 76 weeks after starting pembrolizumab therapy as third-line treatment for lung cancer (left pulmonary large cell neuroendocrine carcinoma), which had been diagnosed at 70 years old. A rapid increase in the blood glucose level from 88 mg/dL (HbA1c, 6.4 %) at admission to 468 mg/dL (C-peptide, 0.07 ng/mL) on day 4 of hospitalization, together with deficiency in insulin secretion, led to a diagnosis of type 1 diabetes mellitus. Adrenal insufficiency due to isolated adrenocorticotropic hormone (ACTH) deficiency was also diagnosed based on his eosinophilia, decreased ACTH (<1.5 pg/mL) and cortisol (1.65 μg/dL) levels, and loading test results. While the diagnostic criteria for fulminant type 1 diabetes mellitus were not met (no evidence of ketosis at the time of the diagnosis), his adrenal insufficiency may have contributed to the suppression of ketone production. This is the first report of the occurrence and diagnosis of type 1 diabetes mellitus and adrenal insufficiency around the same time, which are individually known to be adverse reactions to pembrolizumab. Since adrenal insufficiency may have delayed the manifestation of hyperglycemia, close attention should be paid during diagnostic testing to detect symptoms.
