Additionally, the presence of autoantibodies, such as glutamic acid decarboxylase autoantibodies (GAD), is more prevalent in patients with both T1DM and APS3, suggesting a common autoimmune mechanism [4,5]. Patients with APS3 who have T1DM typically present with an older age at diagnosis and more gradual onset, when compared to individuals with only T1DM, indicating different genetic backgrounds [5]. This evidence concerns the gene GAD1 and type 1 diabetes mellitus.