Seroprevalence of ZnT8, GAD65, IA2 were 17.5%, 51.3% and 12.8% in T1D patients and 2.0%, 2.1%, 6.5% in control participants.***Participants were initially only clinically diagnosed, and 50% were positive for GAD65 despite having long-duration diabetes. This evidence concerns the gene GAD2 and diabetes mellitus.