Role of perceived neighbourhood crime in the longitudinal association between perceived built environment and type 2 diabetes mellitus: a moderated mediation analysis

Background: We examined to what extent perceived neighbourhood crime moderates, associations between type 2 diabetes mellitus (T2DM) and perceived local amenities, recreational facilities, footpaths and public transit, and potential mediation of environmental characteristics-T2DM association by physical activity, social contact, sleep and body mass index (BMI). Methods: The 45 and Up Study data of 36, 224 individuals collected from 2010 to 2015 were analysed in 2019 using multilevel logistic regression to examine the association between T2DM and clustering of unfavourable built environment, and any difference in the association with increasing unfavourable environment and area disadvantage. We performed causal mediation analyses stratified by crime to examine whether crime moderated the strength of identified local amenities-T2DM pathways. Results: The results showed that irrespective of crime, perceived lack of local amenities was associated with increased odds of developing T2DM, and BMI mediated 40% and 30.3% of this association among those who reported unsafe and safe daytime crime, respectively. The proportion mediated by BMI among those who reported unsafe and safe night-time crime was 27.3% and 35.1%, respectively. Walking mediated 5.7% of the local amenities-T2DM association among those who reported safe daytime crime. The odds of T2DM increased with rising unfavourable environment and area disadvantage. Conclusions: The results suggest that the availability of neighbourhood amenities may lower T2DM risk by increasing walking and reducing BMI regardless of area crime. Policies to enhance access to local amenities and prevent crime, especially in disadvantaged areas, may support healthy behaviour and physical health that can potentially reduce T2DM risk