GAD1 and diabetes mellitus: The weak correlation and the discrepancy between RIA and ELISA was reported in other literature comparing commercial kits of anti-GAD antibodies in the diagnosis in type 1 diabetes mellitus, probably due to the differences in assay method (Kawasaki et al., 2019; Kobra Rahmati et al., 2008; Murata et al., 2017; Oikawa et al., 2019), but both ELISA and RIA have high sensitivity for detecting GAD antibodies in type 1 diabetes mellitus.