Background: The development of type 1 diabetes mellitus is preceded by autoimmunity against islet beta cells.
Objective: To determine the risk for islet autoimmunity and childhood diabetes in offspring of affected parents.
Design: Prospective cohort study.
Setting: German BABYDIAB study.
Participants: 1610 offspring of parents with type 1 diabetes.
Measurements: Autoantibodies to islet autoantigens were measured at 9 months, 2 years, 5 years, and 8 years of age.
Results: By 5 years of age, the frequency of islet autoantibodies was 5.9% (95% CI, 4.6% to 7.2%), the frequency of multiple islet autoantibodies was 3.5% (CI, 2.5% to 4.5%), and the frequency of diabetes was 1.5% (CI, 0.9% to 2.1%). The risk for diabetes was highest in offspring with multiple autoantibodies (40% within 5 years vs. 3% in offspring with single autoantibodies; P = 0.005). Progression to multiple islet autoantibodies was fastest in children who were autoantibody positive by age 2 years (P < 0.001), and progression to diabetes was inversely related to the age of positivity for multiple autoantibodies (P = 0.02).
Limitations: The findings are limited to childhood diabetes in affected families.
Conclusions: Childhood autoimmune diabetes is associated with autoimmunity that starts before 2 years of age.