Private garden exposure and public park access in relation to type-2 diabetes incidence: a UK Biobank cohort study

BACKGROUND: Existing longitudinal studies examining the relationship between greenspace exposure and incidence of type-2 diabetes (T2D) have primarily operationalized greenspace using vegetation indices. Little is known about the effect of greenspace types (e.g., private gardens) and public park access. METHODS: We investigated the associations between residential greenspace exposure, including private gardens (determined using Ordnance Survey MasterMap™ Greenspace) and public park access, with the incidence of T2D using the UK Biobank (UKBB) data. Public park access, such as nearest distances (i.e., walkable road network and Euclidean), and the number of parks were calculated for each participant. The incidence of T2D was ascertained through linkage of hospital admissions data. Cox proportional hazard models, adjusting for covariates, were used to estimate the hazard ratios (HR) and 95% confidence intervals (CI). We also performed stratified analyses by age, sex, neighbourhood deprivation, and family history of diabetes. RESULTS: Of the 423,282 UKBB participants (mean age:56.36 years) included in the study, 19,648 developed T2D over a median follow-up of 15.41 years. Compared to the first quartile, participants in the highest quartile of private garden cover (%) had a reduced risk of T2D (HR: 0.932; 95%CI: 0.88, 0.983). For park access, nearest distance (whether walkable or Euclidean) was not associated with the incidence of T2D. However, having a higher number of parks, particularly three or more parks within an 800-m buffer of the home location, was found to lower the incidence of T2D (HR: 0.943; 95% CI: 0.906, 0.981). Stratified analyses revealed that the beneficial effects of private gardens were stronger among participants in deprived areas and those without a family history of diabetes. CONCLUSION: Private residential gardens exposure (often overlooked in greenspace-health research) and a higher number of parks around homes were found to lower the incidence of T2D. This has implications for urban planning and public health, particularly in the prevention and management of diabetes.