Adherence to the EAT-Lancet reference diet and risk of type 2 diabetes, mediation by body mass index

BACKGROUND: Prevalence of diabetes has more than tripled since 1980. Urbanization, more sedentary lifestyles, and modern diets high in fat, sugar and salt are among the main causes of this increased incidence. A diet rich in healthy plant-based products is a way to prevent T2D (4) but has also impact on the natural resources and environment. In 2019 the EAT-Lancet Commission proposed a planetary, healthy, and reference diet, designed to reduce the global health-environmental double burden of current dietary patterns. The objective of this study was to investigate the association between the EAT-Lancet reference diet and type 2 diabetes (T2D) risk. METHODS: The study was conducted using data from 88,964 adults participating to the French NutriNet-Santé cohort 2009-2022 (78.8 % female; mean (SD) baseline age of participants was 43.8 (14.5) y). The endpoint was incident T2D. The main exposure was the EAT-Lancet Diet Index (ELD-I) modelled as sex-specific quintiles (Qs). Hazard Ratios (HRs) and Confidence Intervals (CIs) were assessed by Cox proportional hazards models adjusted for potential confounders. A mediation analysis was also implemented. The role of body mass index (BMI) as a potential mediating factor in the relationship was investigated. FINDINGS: During follow-up (median = 6.79 y), 812 incident T2D cases occurred. The ELD-I ranged from −192 to 429 points with a mean (SD) score of 43.4 (25.7) points. Compared with the participants who had lower adherence to the EAT-Lancet reference diet, those with higher had a 29 % lower risk of T2D (HRQ5vs.Q1: 0.71; 95% CI: 0.56, 0.89; Ptrend = 0.0024). The association studied was mediated up to 58 % by BMI. INTERPRETATION: In this large cohort study, higher adherence to the EAT-Lancet reference diet was associated with a decreased risk of T2D beyond body weight change. These results support previous findings and highlights the interest of the EAT-Lancet reference diet as a healthy and sustainable diet. KEY MESSAGES: • Higher adherence level to the EAT-Lancet reference diet was associated with a decreased of type 2 diabetes risk. • The association between the EAT-Lancet reference diet and the occurrence of type 2 diabetes is partially mediated by BMI.