Aims/hypothesis: To examine the prevalence of sub-: clinical islet autoimmunity in children from two countries with a twofold to threefold difference in incidence of childhood Type I (insulin-dependent) diabetes mellitus.
Methods: Sera were collected from 2,860 English and 3,053 Lithuanian non-diabetic schoolchildren according to the same protocol. Occult diabetes was excluded by blood glucose measurement. Antibodies to GAD and the protein tyrosine phosphatase IA-2 were measured with standardised radiobinding assays in a single laboratory. Islet cell antibodies and insulin autoantibodies were additionally measured in all samples with GAD and/or IA-2 antibody levels above the 97.5th centile of the English schoolchildren.
Results: Of Lithuanian schoolchildren 2.7 % had GAD antibodies above the 97.5th centile of the English schoolchildren but only 0.2 % had antibodies to IA-2 above this threshold (p < 0.001). Islet cell and/ or insulin autoantibodies above the 97.5th centile were found in 22 Lithuanian and 16 English schoolchildren and the overall prevalence of two or more antibodies on or above the 97.5th centile was similar [0.7 % (0.5-1.1) vs 0.6 % (0.4-1.0)] in the two cohorts.
Conclusion/interpretation: The prevalence of multiple antibody markers was similar in the cohorts from the two populations, despite the two to three-fold difference in incidence of diabetes. The unexpectedly high prevalence of subclinical islet autoimmunity suggests that the incidence of diabetes in Lithuania is likely to increase in the near future.