Clinical and molecular evaluation of insulin autoimmune syndrome in a woman with Graves' disease who subsequently became pregnant: A case report

Insulin autoimmune syndrome or Hirata's disease is a rare condition characterized by hypoglycemia associated with endogenous autoimmune hyperinsulinism. This report concerns the case of a 28-year-old Latin American woman with Graves' disease who developed insulin autoimmune syndrome and then subsequently became pregnant. She displayed symptoms related to severe hypoglycemia due to hyperinsulinemia, elevated C-peptide, and anti-insulin antibodies. Prior to pregnancy she was treated with corticosteroids and had ablative treatment with iodine-131. During follow-up of both conditions, the patient became pregnant, and clinically and biochemically hyperthyroid, for which total thyroidectomy was performed during the second trimester of pregnancy. Anti-insulin antibodies, blood glucose, and C-peptide remained normal throughout pregnancy. At 40 weeks of gestation she gave birth to a healthy female newborn with normal blood glucose values. Molecular genetic analysis determined the following genotypes: HLA-DRB1*03:01 / HLA-DRB1*04:01 in the mother; and HLA-DRB1*04:01 / HLA-DRB1*08:02 in the daughter. Because some HLA-DRB1*04 alleles are associated with susceptibility to insulin autoimmune syndrome induced by environmental factors, the patient was advised regarding the future use of drugs with a sulfhydryl group and possible triggering factors for insulin autoimmune syndrome. At 6-month follow-up the daughter presented normal growth and development, as well as normal plasma glucose values, and this remained the case at five-year follow-up.