High-Titer Autoantibodies against Glutamic Acid Decarboxylase Plus Autoantibodies against Insulin and IA-2 Predicts Insulin Requirement in Adult Diabetic Patients

• Published in: Journal of autoimmunity Vol. 12; no. 2; pp. 131 - 135
• Main Authors: Kasuga, Akira, Maruyama, Taro, Nakamoto, Shinya, Ozawa, Yukako, Suzuki, Yutaka, Saruta, Takao
• Format: Journal Article
• Language: English
• Published: London Elsevier Ltd 01.03.1999; Elsevier
• Subjects: Adult; Autoantibodies - blood; Autoantigens; Biological and medical sciences; Biomarkers; Diabetes Mellitus, Type 1 - drug therapy; Diabetes Mellitus, Type 1 - immunology; Diabetes. Impaired glucose tolerance; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Female; GAD antibody, HLA class II, IAA, IA-2 antibody, type 1 diabetes; Glutamate Decarboxylase - immunology; Histocompatibility Antigens Class II; Humans; Insulin - therapeutic use; Insulin Antibodies - blood; Male; Medical sciences; Membrane Proteins - immunology; Middle Aged; Protein Tyrosine Phosphatase, Non-Receptor Type 1; Protein Tyrosine Phosphatases - immunology; Receptor-Like Protein Tyrosine Phosphatases, Class 8; GAD antibody, HLA class II, IAA, IA-2 antibody, type 1 diabetes; Endocrinopathy; Pancreatic hormone; Replacement therapy; Class II histocompatibility antigen; Biological marker; IA 2 antigen; Autoimmune disease; Lyases; Protein hormone; Immunological investigation; Carboxy-lyases; Predictive value; Adult; Human; Immunopathology; Enzyme; Antibody; Langerhans islet; Autoantibody; Glutamate decarboxylase; Insulin; Carbon-carbon lyases; Chemotherapy; Treatment; Follow up study; Insulin dependent diabetes
• ISSN: 0896-8411; 1095-9157
• DOI: 10.1006/jaut.1998.0261

Antibodies against glutamic acid decarboxylase (GADA) is known to be a good predictive marker for insulin-dependency among adult diabetic patients. However, since not all of the GADA-positive patients will develop insulin requirement, we investigated whether other markers, that is, antibodies against IA-2 (IA-2A), insulin autoantibodies (IAA) and HLA class II type, would affect its predictive value for insulin requirement. Adult diabetic patients in the non-insulin-requiring stage were screened for GADA and registered in the study if positive. At the end of the follow-up period, 15 of the 43 GADA-positive patients required insulin. Among GADA-positive patients, the GADA titers of the insulin-requiring patients were significantly higher (199Uvs.5.8U,P<0.001) and high-titer GADA was more frequently detected among insulin-requiring patients (80%vs.11%,P<0.0001). IAA was more frequently detected in insulin-requiring patients (40%vs.0%,P<0.001), and IA-2A was detected only among insulin-requiring patients. Combinations of these three antibodies (GADA with either IAA or IA-2A) had 100% positive predictive value. In conclusion, the GADA test is a good screening test for predicting insulin requirement in adult diabetic patients and both the IAA and IA-2A tests are useful second line tests.