The association between timing of complementary food introduction and age at diagnosis of type 1 diabetes was investigated among 1077 children in the SEARCH for Diabetes in Youth study. Age at diagnosis was 5 months earlier for children introduced to sugar-sweetened beverages (SSB) in the first 12 months of life compared with those who were not (9.0±0.2 vs 9.5±0.1; P=0.02) independent of human leukocyte antigen (HLA) risk status. Analyses stratified by HLA risk status found that children with a high-risk HLA genotype had an earlier age at diagnosis if they were introduced to fruit juice in the first year of life (mean age at diagnosis=9.3±0.1, 9.1±0.1 and 9.6±0.2 for introduction at ⩽6 months, between 7 and 11 months and ⩾12 months, respectively; P=0.04). Introduction of SSB in the first year of life may accelerate the onset of type 1 diabetes independent of HLA risk status.