INS and pancreatic insulinoma: Insulin Autoimmune Syndrome (IAS), first described by Dr. Hirata in 1970 [4], is a rare but significant cause of spontaneous, non-fasting (reactive) hypoglycemia characterized by hyperinsulinemic hypoglycemia in individuals without prior exposure to insulin or an insulinoma, and defined by very high titers of polyclonal insulin autoantibodies (IAA) [5].