The mediating role of the food environment, greenspace, and walkability in the association between socioeconomic position and type 2 diabetes — The Maastricht Study

Aims: This study investigates the interplay between socioeconomic position (SEP), the residential food environment, walkability, greenspace, and type 2 diabetes (T2D), particularly whether the environmental factors mediate the association between SEP and T2D. Methods: SEP, T2D status, residential Food Environment Healthiness Index (FEHI), number of fast-food outlets (FF), walkability index (WI), and proportion of greenspace (GS) were ascertained in 9188 participants. The associations between SEP, the environment and T2D were modeled with logistic regression and survival analysis. The proportion of mediation of the association between SEP and T2D was estimated with causal mediation analysis. Results: Lower SEP was associated with higher risk of T2D. Hazard ratios (HR) were 2.03 (95 % CI 1.60–2.58), 1.79 (1.40–2.30) and 1.77 (1.21–2.58) for an interquartile range decrease (IQR) of education, income, and occupation, respectively. HRs for IQR changes of the environmental factors were: FEHI 1.20 (1.00–1.43), FF 0.87 (0.76–0.99), WI 1.23 (0.95–1.58) and GS 1.16 (0.96–1.43). Regression on prevalent T2D yielded similar results. Lower socioeconomic position was associated with a less healthy environment (e.g., FEHI -0.10 (-0.12–-0.07) for education). Environmental exposures mediated between 0.1 % (-0.7–0.9) and 2.6 % (0.4–5.2) of the cross-sectional associations and 0.3 % (-8.6–8.6) and 8.5 % (2.3–27.4) of the longitudinal associations. Conclusions: People with lower SEP had higher risk and prevalence of T2D and lived in a slightly less healthy residential environment. The association between SEP and T2D is not strongly mediated by FEHI, FF, WI, or GS.