Development of Fulminant Type 1 Diabetes Mellitus in the Course of Treatment with Atezolizumab for Hepatocellular Carcinoma

A 71-year-old woman with recurring stage IV hepatocellular carcinoma (HCC) was admitted to our hospital while being treated with atezolizumab and bevacizumab and complained of fatigue, vomiting, and appetite loss. The following were noted on admission: serum glucose level, 633 mg/dL; metabolic acidemia (HCO(3)(−) of 19.5 mmol/L); remarkably low serum and urinary C-peptide levels (0.16 ng/mL and ≤1.5 μg/day, respectively); and urinary ketone body level, 4,197 μmol/L. She was diagnosed with atezolizumab-induced fulminant type 1 diabetes mellitus (T1DM), and insulin therapy improved the symptoms. To our knowledge, this a novel report of atezolizumab-induced fulminant T1DM in an HCC patient.