Background: The association between atopic dermatitis (AD) and cardio-metabolic risk factors is not yet established. Furthermore, no validated questionnaire-based method of identifying adults with AD is currently available. Objectives: To assess the cardio-metabolic risk in adults with a history of AD using 3 different questionnaire-based diagnostic criteria. Methods: We utilized data from a general population study including questionnaire data and objective measurements of 9656 Danish adults. To identify adults with a history of AD, we used a question regarding physician-diagnosed AD and 2 versions of the UK Working Party Diagnostic Criteria. Associations between AD status and cardio-metabolic endpoints were estimated using survey weighted logistic and linear regression analysis. Results: We identified 462 (4.8%) adults with self-reported physician-diagnosed AD, whereas 903 (9.4%) and 226 (2.3%) had AD according to the UK Working Party Criteria when at least 2 and 3of 4 minor criteria were fulfilled. The populations were not comparable in terms of occurrence of cardio-metabolic risk factors. For example, the prevalence of obesity was lower in participants with physician-diagnosed AD but overall higher in UK 2/4 and UK 3/4. Conclusion: Due to the heterogeneity in the captured study populations in terms of the studied outcomes and absence of a gold standard, no conclusions regarding the cardio-metabolic risk in adults with AD in a general population could be made. This study serves as an example of the challenges that are often encountered in questionnaire-based epidemiologic studies and highlights the need of better definitions for this patient group.