Triolo TM, et al. - In the present study, researchers analyzed the development of islet autoantibodies (Ab+) and type 1 diabetes, as well as the impacts of genetic factors and common environment on Ab+ in identical twins (IT), nonidentical twins (NT), and full siblings (FS). Study participants from the TrialNet Pathway to Prevention Study were screened from 2004 to 2015 for Ab+. For initially multiple and single Ab+ IT and multiple Ab+ NT, the risk of type 1 diabetes at 3 years was high. Significant risk factors for the development of Ab+ in twins were genetic predisposition, age, and male sex.