T-Cell-Mediated Autoimmunity May Be Involved in Fulminant Type 1 Diabetes

According to the new classification of diabetes by the American Diabetes Association (1,2), type 1B diabetes is considered to be “idiopathic,” i.e., of unknown origin. However, the existence of type 1B diabetes itself has not yet been defined. Recently, a subtype of type 1B diabetes, so-called “fulminant” type 1 diabetes, has been proposed (3). This type of type 1 diabetes is characterized by the following criteria: 1) no detectable “islet-associated” autoantibody; 2) regardless of diabetic ketoacidosis, near-normal HbA_1c levels, suggesting extremely acute onset; and 3) high levels of pancreatic exocrine enzymes. On pancreatic biopsy in this type of type 1 diabetes, no insulitis is found, although infiltration of T-cells in exocrine tissue is observed. On the other hand, Tanaka et al. (4) reported that, at autopsy, clear CD8-dominant insulitis …