We studied dietary risk factors by analysing a questionnaire administered at birth, 1 year and 2(1/2) years of age, as well as the level of glutamic acid decarboxylase autoantibodies (GADA) and tyrosine phosphatase autoantibodies (IA-2A), in 7208 2(1/2)-year-old children from the All Babies in Southeast Sweden cohort, using the 95th percentile cut-off for autoantibodies to identify children at risk of type 1 diabetes. A total of 657 children had either IA-2A (n 360) or GADA (n 335), and thirty-eight children had both GADA and IA-2A. In univariate analysis, male gender and maternal coeliac disease implied a risk of possessing IA-2A. Maternal type 2 diabetes, a high consumption of fresh cows milk at the age of 1 year and a late introduction of gluten were associated with a risk of GADA. Early cessation of breast-feeding (< 2 months of age) was associated with a risk of the simultaneous occurrence of both IA-2A and GADA. In logistic regression analysis, a high consumption of milk at the age of I year (odds ratio 2.6)represented a risk for GADA, and maternal coeliac disease (odds ratio 2.9) represented a risk for IA-2A. The combination of an early introduction of cows milk formula and a late introduction of gluten-containing food gave an odds ratio of 6.0 for positivity for at least one autoantibody at 1 and 21 years of age. The induction of autoantibodies by the age of 2(1/2) years has a male preponderance and is more common in children with maternal type 2 diabetes or maternal coeliac disease. Dietary risk factors for the induction of beta-cell autoantibodies in 21-year-old children are a short duration of breast-feeding, an early introduction of cows milk formula and a late introduction of gluten, as well as a high consumption of milk at the age of I year.