Diabetic ketoacidosis after the second dose of SARS-CoV-2 mRNA vaccination in a patient with pembrolizumab-induced fulminant type 1 diabetes

We report a case of 77-year-old woman with fulminant type 1 diabetes (T1D) who developed diabetic ketoacidosis (DKA) after the second dose of SARS-CoV-2 vaccine tozinameran. The patient had been diagnosed as having T1D associated with an immune-related adverse event caused by pembrolizumab at the age of 75. After the second dose of tozinameran, she developed DKA and needed intravenous insulin infusion and mechanical ventilation. Although the direct causal relationship between the vaccination and the DKA episode could not be proven in this case, published literatures had suggested the possibility of developing DKA after SARS-CoV-2 vaccination in patients with T1D. As the magnitude of the risk of the combination of the known adverse drug reactions of SARS-CoV-2 mRNA vaccine and T1D patients’ vulnerability to sick-day conditions is not yet thoroughly assessed, future studies such as a non-interventional study with adequate sample size would be required to address this issue.