A Patient with Type 1 Diabetes Mellitus and Graves' Disease with a High-titer of Anti-Glutamic Acid Decarboxylase Antibody

Abstract

A 57-year-old Japanese woman admitted in April 2000 with diabetes associated with hyperthyroidismlasting 10 months had been treated with insulin for diabetes mellitus, but not for hyperthyroidism.Graves'disease was diagnosed by the presence of thyroid stimulating receptor antibody and increased uptake ofTc-99 m on thyroid scintigraphy, and treated with thiamazole. Decreased 24-hour urinary C-peptide output(8.7, μg/day)and the presence of islet cell antibodies and high titer(74, 100 U/ml)antiglutamic acid decarboxylaseantibody yielded a diagnosis of type 1 diabetes.She underwent intensive conventional insulin therapy.Immunoblotting using the patient's serum showed 65 kDa protein in the rat pancreas, thyroid, and adrenaltissues.
A possible common autoimmune abnormality may underlie the pathogenesis of the 2 disorders.