EAT-Lancet diet, accelerated biological aging, and type 2 diabetes risk: a cohort study from the UK Biobank

Background The EAT-Lancet planetary health diet emphasizes dietary patterns that may benefit both human health and environmental sustainability. Although adherence to this diet has been associated with lower chronic disease risk, its relationship with incident type 2 diabetes (T2D) and the potential mediating role of biological aging remain unclear. Methods We included 155,413 UK Biobank participants without T2D at baseline who had completed at least one 24-h dietary recall and had available biological aging indicators. Adherence to the EAT-Lancet diet was assessed using the Stubbendorff and Knuppel indices. Biological aging was evaluated using Klemera-Doubal method biological age (KDM-BA) and PhenoAge acceleration. Multivariable linear regression, Cox proportional hazards models, restricted cubic splines, interaction analyses, and mediation analyses were performed, respectively. Results Higher adherence to both EAT-Lancet diet indices was associated with lower accelerated biological aging and lower T2D risk. In fully adjusted models, participants in the highest quartile of the Knuppel and Stubbendorff indices had lower T2D risk than those in the lowest quartile (HR 0.83, 95% CI: 0.74–0.92; and HR 0.85, 95% CI: 0.78–0.92, respectively). While, accelerated biological aging was statistically associated with higher T2D risk; the highest quartiles of KDM-BA and PhenoAge acceleration showed HRs of 2.36 (95% CI: 2.18–2.56) and 2.84 (95% CI: 2.58–3.11), respectively. Exploratory mediation analyses suggested that KDM-BA and PhenoAge acceleration statistically accounted for approximately 33–44% of the observed association between EAT-Lancet diet adherence and incident T2D. Conclusion Greater adherence to the EAT-Lancet diet was associated with lower risk of incident T2D, and this association was partly mediated by slower biological aging. These findings support integrated prevention strategies that promote healthy dietary patterns and mitigate accelerated aging.