Thus, we aimed to investigate the association between GAD65 antibody levels measured using a competition assay, which increases the precision of the assessment of autoantibody positivity, and incident adult-onset diabetes in a large, multi-centre, population-based prospective study in eight European countries in people who were over 40 years of age and free of known diabetes at baseline. This evidence concerns the gene GAD2 and type 2 diabetes mellitus.