title: Autoimmune hypoglycemia in a patient with characterization of insulin receptor autoantibodies.
abstract: BACKGROUND
  Type B insulin resistance syndrome is a manifestation of autoantibodies to the insulin receptor that results in severe hyperglycemia and acanthosis nigricans. However, the mechanisms by which these autoantibodies induce hypoglycemia are largely unknown. In this paper, we report the case of patient with type B insulin resistance syndrome who presented with frequent severe fasting hypoglycemia and acanthosis nigricans.
  
  
  METHODS
  To evaluate the mechanism of hypoglycemia, we measured the inhibition of insulin binding to erythrocytes and IM9 lymphocytes in a sample of the patient's dialyzed serum before and after immunosuppressive therapy.
  
  
  RESULTS
  In the patient's pre-treatment serum IgG, the binding of (125)I-insulin to erythrocytes was markedly inhibited in a dose-dependent manner until the cold insulin level reached 10(-9) mol/L. We also observed dose-dependent inhibition of insulin binding to IM9 lymphocytes, which reached approximately 82% inhibition and persisted even when diluted 1:20. After treatment with glucocorticoids, insulin-erythrocyte binding activity returned to between 70% and 80% of normal, while the inhibition of insulin-lymphocyte binding was reduced by 17%.
  
  
  CONCLUSIONS
  We treated a patient with type B insulin resistance syndrome showing recurrent fasting hypoglycemia with steroids and azathioprine. We characterized the patient's insulin receptor antibodies by measuring the inhibition of insulin binding.
authors.affiliation: Department of Endocrinology and Metabolism, Kyung Hee University School of Medicine, Seoul, Korea.
authors.forename: Suk
authors.initials: S
authors.lastname: Chon
authors.forename: Moon Chan
authors.initials: MC
authors.lastname: Choi
authors.forename: Yun Jung
authors.initials: YJ
authors.lastname: Lee
authors.forename: You Cheol
authors.initials: YC
authors.lastname: Hwang
authors.forename: In-Kyung
authors.initials: IK
authors.lastname: Jeong
authors.forename: Seungjoon
authors.initials: S
authors.lastname: Oh
authors.forename: Kyu Jeung
authors.initials: KJ
authors.lastname: Ahn
authors.forename: Ho Yeon
authors.initials: HY
authors.lastname: Chung
authors.forename: Jeong-Taek
authors.initials: JT
authors.lastname: Woo
authors.forename: Sung-Woon
authors.initials: SW
authors.lastname: Kim
authors.forename: Jin-Woo
authors.initials: JW
authors.lastname: Kim
authors.forename: Young Seol
authors.initials: YS
authors.lastname: Kim