Objectives:The aim of the study was to evaluate the gluten-free diet (GFD) adherence after 1 year of follow-up in children with screening-detected celiac disease (CD) in a general population.Methods:A total of 18,325 twelve-year-olds were invited to participate in a population-based CD screening (Exploring the Iceberg of Celiacs in Sweden), of whom 13,279 participated. In 240 children, CD was detected through elevated anti-tissue transglutaminase antibodies 2 (TG2-IgA) and verified by a small-intestinal biopsy. This substudy included 210 children with TG2-IgA, evaluated both at the initial biopsy occasion and at 1-year follow-up. GFD adherence was evaluated by a combination of TG2-IgA measurements and self-reported adherence (n=193).Results:After 1 year, 85% (179/210) had normalized TG2-IgA levels (less than5 U/mL). Among those who had greater than50 U/mL at diagnosis, 25% (16/63) still had elevated TG2-IgA, but for the majority their initial values were more than halved. Most reported a high level of GFD adherence (always 82% [158/193] and often 16% [30/193]), and 75% [145/193] reported always adhering combined with normalized TG2-IgA. Although reporting that they were always adherent, 13 (6.7%) had not yet normalized their TG2-IgA levels completely; however, a majority of these initially had the highest TG2-IgA levels.Conclusions:GFD adherence is high in adolescents with CD detected by screening of the general population of Swedish 12-year-olds. Almost all of them had normalized serology and reported GFD adherence at the 1-year follow-up. A few adolescents who reported GFD adherence, however, had elevated TG2-IgA levels, suggesting more severe disease and/or nonadherence.