COMPARISON OF A NEW ANTI-GLUTAMIC ACID DECARBOXYLASE (GAD) ENZYME-LINKED-IMMUNOSORBENT-ASSAY (ELISA) WITH RADIOIMMUNOASSAY METHODS - A MULTICENTER STUDY

Several methods are available for the measurement of antibodies to glu tamic acid decarboxylase (anti GAD). These antibodies are valuable too ls for the immunodiagnosis of insulin-dependent (type 1) diabetes mell itus (IDDM) and for the assessment of risk for the future development of IDDM. We here describe a new enzyme-linked immunosorbent assay (ELI SA) for the detection of anti-GAD which was tested in a multicenter st udy. The results of the new anti-GAD ELISA correlate well with those o btained by radioimmunoassays (RIA) and they have a higher sensitivity (69%) and specificity (98%) compared to other anti-GAD enzyme immunoas says as determined in the IDW Proficiency Test Program for the detecti on of GAD antibodies. The new ELISA is simple and easy to perform, wit h convenient handling of the reagents. Quantitative and reproducible t est results are available within approximately four hours. The new ant i-GAD ELISA can be used for large scale population screening to indica te a prediabetic state as well as to diagnose autoimmune diabetes in a dults (LADA) and the risk for IDDM in pregnant women with gestational diabetes.