ABSTRACT
Autoimmune insulin syndrome is characterized by insulin autoantibody, hyperinsulinemia, and fasting hypoglycemia without previous insulin immunization. This syndrome shows discordant levels between immunoreactive insulin and C-peptide. Negative results of an anatomic study of the pancreas and an inability to reproduce hypoglycemia during a prolonged fast may be helpful in excluding insulinoma. Symptomatic hypoglycemia usually develops during an oral glucose tolerance test. This syndrome is a self-limited disorder. Recently, we experienced one case that developed symptomatic hypoglycemia during both the fasting & oral glucose tolerance test, and another that developed symptomatic hypoglycemia during the oral glucose tolerance test but not the fasting test. Hereby, we present these cases with a review of the literature.