ISLET-CELL ANTIBODIES PREDICT INSULIN-DEPENDENT DIABETES IN UNITED-STATES SCHOOL-AGE-CHILDREN AS POWERFULLY AS IN UNAFFECTED RELATIVES

Islet cell antibodies (ICA) in the sera of nondiabetic relatives of pa tients with insulin-dependent diabetes (IDD) are predictive of the dis ease, a finding that permits the design of intervention strategies to prevent it. However, 85% or more of patients with new onset IDD have n o affected relative. We therefore screened 9,696 schoolchildren betwee n the ages of 5 and 18 yr (mean age 10.7 yr) in Pasco County, Florida for ICA in three surveys during 1984/5, 1987/8, and 1990/1 and have fo llowed them prospectively. Approximately 4,000 of these children have been followed for nearly 8 yr. ICA titers greater than or equal to 10 Juvenile Diabetes Foundation units on replicate tests were detected in 57 of the children (0.59%). 10 children have developed diabetes so fa r, and all had ICA detected beforehand. The likelihood of developing I DD among the ICA-positive children was compared with 2,959 age-matched nondiabetic first degree relatives of IDD probands who were screened for ICA by our laboratory during the same time period and also followe d prospectively. Of 103 (3.5%) ICA-positive relatives, 31 have develop ed IDD. Life table analysis reveals no statistically significant diffe rences in the probability of developing IDD between the ICA-positive s choolchildren and ICA-positive first degree relatives (P = 0.3). The e stimated risk of developing IDD by 7 yr in the ICA-positive schoolchil dren was 45% (95% confidence interval 15-74%) compared with 43% (confi dence interval 22-63%) in the relatives. We conclude that ICA appear t o be as predictive of IDD in low-risk schoolchildren as they are in hi gh-risk relatives. These data suggest that it is feasible to predict I DD by screening a general population of schoolchildren for ICA and tha t those found to be positive could be considered, in addition to relat ives, for intervention protocols to prevent the disease.