Hepatocellular Carcinoma Complicated by Fulminant Type 1 Diabetes Mellitus Shortly After Initiation of Durvalumab Plus Tremelimumab

A 64-year-old man with cirrhosis was diagnosed with unresectable hepatocellular carcinoma and treated with a combination of durvalumab and tremelimumab. The patient had no history of diabetes mellitus. Three weeks later, the patient developed general fatigue, dry mouth, and polyuria. A subsequent blood examination revealed a blood glucose level of 706 mg/dL and C-peptide level of 0.29 ng/mL, with an HbA1c of 6.4%. The patient was diagnosed with fulminant type 1 diabetes mellitus. Although fulminant type 1 diabetes mellitus is a rare immune-mediated adverse event, it requires prompt attention shortly after the initiation of these agents owing to its severe and emergent nature.