OBJECTIVE: Earlier studies suggest that children with type 1 diabetes are more likely to have a subsequent diagnosis of celiac disease. However, research is sparse on the risk of subsequent type 1 diabetes in individuals with celiac disease. We sought to determine the risk of subsequent type 1 diabetes diagnosed before the age of 20 years in children and adolescents with celiac disease in a national, general population-based cohort. RESEARCH DESIGN AND METHODS: We identified 9,243 children with a diagnosis of celiac disease in the Swedish national inpatient register between 1964 and 2003. We then identified five reference individuals matched at time of diagnosis for age, calendar year, sex, and county (n = 45,680). Only individuals with >1 year of follow-up after study entry (diagnosis of celiac disease) were included in the analyses. RESULTS: Celiac disease was associated with a statistically significantly increased risk of subsequent type 1 diabetes before age 20 years (hazard ratio 2.4 [95% CI 1.9-3.0], P