Risk factors for IDD have been studied in relatives of patients, in whom the risk is far higher than in the children from the background population. Several factors have been identified as the genetic background at the HLA level (DR and DQ regions) and autoantibodies like islet cells antibodies (ICA) and insulin autoantibodies (IAA). 8,363 sera from schoolchildren (age 6-17 yr) have been tested for the presence of ICA. 150 sera (1.8%) were found positive; the prevalence rate of high ICA titres (> or = 20 uJDF) was very low: 0.2%. ICA titres remained stable over a 8 mth follow-up period. IAA have been measured on the first 2,000 sera and the prevalence rate was 1.2%. Only 3 sera were found positive for the two antibodies, one coming from a diabetic girl. The distribution of the susceptibility alleles at the DQ-HLA region was similar among the ICA-positive and ICA-negative children.