Development of a hyperosmolar-hyperglycemic state and possible fulminant type 1 diabetes mellitus during the treatment of a case of adenocarcinoma of the lung and interstitial pneumonia.

An 85-year-old man was being treated with anti-cancer drugs for adenocarcinoma of the lung and was on a tapering dose of prednisolone for interstitial pneumonia. He attended our hospital complaining of fatigue, thirst, and polyuria in September 2020. His postprandial plasma glucose concentration was 976 mg/dL, his glycated hemoglobin was 8.0%, his plasma osmolality was 342 mOsm/kg H2O, his urine ketone body content was 1 +, and his blood pH was 7.356. Therefore, we diagnosed a hyperosmolar-hyperglycemic state and he was admitted to the hospital for treatment. He had had no previous upper respiratory symptoms, and his postprandial plasma glucose and glycated hemoglobin were normal 13 days before he was first assessed (90 mg/dL and 5.9%, respectively). On admission, his serum pancreatic exocrine enzyme activities were high and he was negative for islet-specific autoantibodies. His serum C-peptide concentration was 0.60 ng/mL, suggesting that his endogenous insulin secretion was partially intact at that time. Although he did not meet the diagnostic criteria, we suspected him of having fulminant type 1 diabetes mellitus, because of the abrupt onset of hyperosmolar-hyperglycemic state. His general condition was improved by fluid and insulin administration. His human leukocyte antigen genotype was DRB1*04:05 DQB1*04:01:01, which is a disease susceptibility haplotype for fulminant type 1 diabetes mellitus. In addition, his prednisolone treatment may have caused an autoimmune abnormality, further predisposing toward the development of fulminant type 1 diabetes mellitus. © The Japan Diabetes Society 2022.