Since the 1980s, we have been gaining knowledge about the pathogenesis of type 1 diabetes and found that the measurement of diabetes-associated autoantibodies against insulin, glutamic acid decarboxylase, insulinoma-associated protein 2, and zinc transporter 8 has a central role in recognition of early stages of the disease in asymptomatic people. In the 1990s, large prospective studies were established in Finland (the Diabetes Prediction and Prevention [DIPP] study1), Germany (the BABYDIAB study2), Sweden (Diabetes Prediction in Skåne Study3), and the USA (the Diabetes Autoimmunity Study in the Young [DAISY]4) that followed up children with a high genetic risk of developing type 1 diabetes from birth until diagnosis of clinical type 1 diabetes.