Occurrence of Type 1 Diabetes in Graves' Disease Patients Who Are Positive for Antiglutamic Acid Decarboxylase Antibodies: An 8-Year Followup Study

Glutamic acid decarboxylase antibodies (GADAs) are one of the markers of islet cell autoimmunity and are sometimes present before the onset of type 1 diabetes (T1D). GADA can be present in Graves' patients without diabetes; however, the outcome of GADA-positive Graves' patients is not fully understood, and the predictive value of GADA for the development of T1D in Graves' patients remains to be clarified. We investigated the prevalence of GADA in 158 patients with Graves' disease and detected GADA in 10 patients. They were followed up to discover whether or not T1D developed. In the course of eight years, 2 patients with high titers of GADA developed T1D, both had long-standing antithyroid drug-resistant Graves' disease. Thus, Graves' disease with high GADA titer seems to be at high risk for T1D.