GAD1 and type 1 diabetes mellitus: Also in children and adolescents with T1DM, previous studies agree on the age and gender effect (1,3,4,17,18), while there are very limited studies on the significance of the persistence of anti-GAD (4,16), the age at diabetes diagnosis (1,4), and diabetes duration (4,18,19) on the development of thyroid antibody positivity.