Prospective evaluation of risk factors for the development of islet autoimmunity and type 1 diabetes during puberty--TEENDIAB: study design.

Type 1 diabetes (T1D) has a peak incidence in childhood and adolescence. The TEENDIAB study investigates the period of puberty and adolescence in the natural course of T1D development. Evidence suggests that the immune phenotype of children developing autoimmunity during puberty and adolescence differs from that in childhood. We hypothesize that these differences reflect heterogeneity in the genetic and environmental factors that influence the development of autoimmunity in puberty versus early infancy. TEENDIAB is an observational cohort study that enrols and follows 1500 children aged 8-12 and who have a first degree relative with T1D to test this hypothesis. Data collection and analyses will focus on determining the phenotype of islet autoimmunity, genotypes of T1D- and type 2 diabetes-associated genes, insulin resistance, and β-cell function, growth, obesity, and physical exercise. The findings of this study will increase the understanding of pathogenetic mechanisms behind the increasing diabetes incidence in youth and the impact of obesity on diabetes development in this age period.