Diabetes Metab J.  2020 Apr;44(2):260-266. 10.4093/dmj.2019.0007.

Glutamic Acid Decarboxylase Autoantibody Detection by Electrochemiluminescence Assay Identifies Latent Autoimmune Diabetes in Adults with Poor Islet Function

Affiliations
  • 1Department of Endocrinology, Sir Run Run Hospital, Nanjing Medical University, Nanjing, China
  • 2Department of Endocrinology, The First Affiliated Hospital, Nanjing Medical University, Nanjing, China
  • 3Department of Metabolism and Endocrinology, The Second Xiangya Hospital, Central South University, Changsha, China
  • 4Key Laboratory of Diabetes Immunology (Central South University), Ministry of Education, National Clinical Research Center for Metabolic Diseases, Changsha, China

Abstract

Background
The detection of glutamic acid decarboxylase 65 (GAD65) autoantibodies is essential for the prediction and diagnosis of latent autoimmune diabetes in adults (LADA). The aim of the current study was to compare a newly developed electrochemiluminescence (ECL)-GAD65 antibody assay with the established radiobinding assay, and to explore whether the new assay could be used to define LADA more precisely.
Methods
Serum samples were harvested from 141 patients with LADA, 95 with type 1 diabetes mellitus, and 99 with type 2 diabetes mellitus, and tested for GAD65 autoantibodies using both the radiobinding assay and ECL assay. A glutamic acid decarboxylase antibodies (GADA) competition assay was also performed to assess antibody affinity. Furthermore, the clinical features of these patients were compared.
Results
Eighty-eight out of 141 serum samples (62.4%) from LADA patients were GAD65 antibody-positive by ECL assay. Compared with ECL-GAD65 antibody-negative patients, ECL-GAD65 antibody-positive patients were leaner (P<0.0001), had poorer β-cell function (P<0.05), and were more likely to have other diabetes-associated autoantibodies. The β-cell function of ECLGAD65 antibody-positive patients was similar to that of type 1 diabetes mellitus patients, whereas ECL-GAD65 antibody-negative patients were more similar to type 2 diabetes mellitus patients.
Conclusion
Patients with ECL-GAD65 antibody-negative share a similar phenotype with type 2 diabetes mellitus patients, whereas patients with ECL-GAD65 antibody-positive resemble those with type 1 diabetes mellitus. Thus, the detection of GADA using ECL may help to identify the subtype of LADA.

Keyword

Autoantibodies; C-peptide; Glutamate decarboxylase; Latent autoimmune diabetes in adults
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