Objective: To evaluate the likely prognostic significance of ICAs in children with no family history of IDDM.
Research design and methods: We examined the prevalence of ICAs in 2925 English schoolchildren aged 9-13 yr and in 274 age-matched siblings of children with diabetes from the same region, and we compared the estimated risk of progression to diabetes within 10 yr in the two groups.
Results: ICAs were present at levels > or = 4 JDF U in 2.8% of schoolchildren and 6.6% of siblings and at > or = 20 JDF U in 0.8% of schoolchildren and 2.2% of siblings. Although ICAs are only 2-3 times more prevalent in siblings than schoolchildren, the estimated cumulative risk that siblings will progress to diabetes by age 21 is 13 times greater (2.8 vs. 0.21%).
Conclusions: ICAs are unexpectedly prevalent in English schoolchildren, but only a small minority, with this evidence of immune activation directed against islet cells, will progress to diabetes. Although ICAs alone have limited predictive value in the general population, combining two or more predictive tests in series could achieve a level of prediction equivalent to that now obtained in first-degree relatives.