Anti-GAD antibody-positive fulminant type 1 diabetes developed following SARS-CoV-2 vaccination

Vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been used worldwide since the 2020 coronavirus pandemic. However, several negative side-effects of these vaccines have been reported. Herein, we present a case of a patient with fulminant type 1 diabetes that developed shortly after administration of the SARS-CoV-2 vaccine. A 47-year-old man with no medical history presented with hyperglycemia-related symptoms shortly after receiving the third messenger ribonucleic acid SARS-CoV-2 vaccine. Based on hyperglycemia, diabetic ketoacidosis at onset, relatively low hemoglobin A1c levels, and complete depletion of endogenous insulin secretion, the patient was diagnosed with fulminant type 1 diabetes and insulin therapy was initiated. Through human leukocyte antigen genotyping, the disease-susceptible alleles for type 1 diabetes, DRB1*04:05 and DQB1*04:01, were identified. The patient tested positive for serum anti-glutamic acid decarboxylase antibodies, which are normally negative for fulminant type 1 diabetes, implying that immunomodulation triggered by SARS-CoV-2 vaccination influenced the onset of type 1 diabetes.