The seroprevalence of GAD in T1D, T2D and controls was 29%, 3.5% and none. The seroprevalence of ICA in the different groups was 21%, 2.7% and none while IAA was 27%, 16% and 2%. IA-2A was absent in all groups.***This results show that GAD continues to be positive in one-third of T1D patients even at a mean of 6 years of disease duration.***The positivity rates of IAA maybe due to insulin treatment in both the T1D and T2D groups (37/86), which may result in false positive results. This evidence concerns the gene GAD1 and type 1 diabetes mellitus.