Higher neighborhood drivability is associated with a higher diabetes risk in younger adults: a population-based cohort study in Toronto, Canada

Objective — Car dependency contributes to physical inactivity and, consequently, may increase the likelihood of diabetes. We investigated whether neighborhoods that are highly conducive to driving confer a greater risk of developing diabetes and, if so, whether this differs by age.

Research Design and Methods — We used administrative healthcare data to identify all working-age Canadian adults (20–64 years) who were living in Toronto on 1 April 2011 without diabetes (type 1 or 2). Neighborhood drivability scores were assigned using a novel, validated index that predicts driving patterns based on built environment features divided into quintiles. Cox regression was used to examine the association between neighborhood drivability and 7-year risk of diabetes onset, overall and by age-group, adjusting for baseline characteristics and comorbidities.

Results — Overall, there were 1,473,994 adults in the cohort (mean age 40.9 ± 12.2 years), among whom 77,835 developed diabetes during follow-up. Those living in the most drivable neighborhoods (quintile 5) had a 41% higher risk of developing diabetes compared with those in the least drivable neighborhoods (adjusted hazard ratio 1.41, 95% CI 1.37–1.44), with the strongest associations in younger adults aged 20–34 years (1.57, 95% CI 1.47–1.68, P < 0.001 for interaction). The same comparison in older adults (55–64 years) yielded smaller differences (1.31, 95% CI 1.26–1.36). Associations appeared to be strongest in middle-income neighborhoods for younger residents (middle income 1.96, 95% CI 1.64–2.33) and older residents (1.46, 95% CI 1.32–1.62).

Conclusions — High neighborhood drivability is a risk factor for diabetes, particularly in younger adults. This finding has important implications for future urban design policies.