Social Inequalities in the Association between Diabetes and Complete Edentulism

Complete edentulism represents the endpoint of oral diseases and can impair quality of life. Although diabetes is linked to oral inflammation, less is known about its relationship with complete edentulism, particularly by diabetes type. This cross-sectional study examined associations between type 1 and type 2 diabetes and complete edentulism using datasets from Denmark and Sweden and assessed whether socioeconomic status modified these associations. A total of 557,316 adults aged 18 to 75 y were included. Complete edentulism was assessed via clinical examination (register data, Sweden) or self-reporting (survey, Denmark). Diabetes was classified using validated register-based definitions. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for complete edentulism by diabetes type, adjusting for potential confounders. Age-stratified prevalence and effect modification by income and education, using additive and multiplicative scales, were examined. Complete edentulism was more prevalent among individuals with type 2 diabetes (Denmark: 4.3%, 95% CI: 4.1 to 4.6; Sweden: 1.7%, 95% CI: 1.5 to 1.7) than among those with type 1 diabetes (Denmark: 2.1%, 95% CI: 1.6 to 2.7; Sweden: 0.7%, 95% CI: 0.6 to 0.8) and without diabetes (Denmark: 1.9%, 95% CI: 1.7 to 2.0; Sweden: 0.7%, 95% CI: 0.6 to 0.7). Adjusted models showed higher odds of complete edentulism in type 1 diabetes (Denmark: OR 1.77, 95% CI 1.31 to 2.39; Sweden: OR 1.27, 95% CI 1.07 to 1.50) and type 2 diabetes (Denmark: OR 1.89, 95% CI 1.68 to 2.12; Sweden: OR 1.73, 95% CI 1.63 to 1.84). Effect modification analyses revealed a consistent direction of association, with an additive effect of lower income and educational attainment, as indicated by positive relative excess risk due to interaction estimates (Denmark: 0.96 to 2.31; Sweden: 0.26 to 1.83). In conclusion, diabetes types 1 and 2 were associated with complete edentulism, especially among socioeconomically disadvantaged groups.