Fulminant type 1 diabetes is a newly identified subtype of type 1 diabetes, characterized by pancreatic islet cell destruction, rapid hyperglycemia, and ketoacidosis. During the onset, the hemoglobin A1c (HbA1c) levels are normal or near-normal.Diabetic ketoacidosis (DKA) and complete β-cell destruction occur within a short period of time. The disease is more likely to develop during the third trimester of pregnancy. 1,2) The dis-