Neighbourhood 'walkability' may influence diabetes risk

By Eleanor McDermid

A Canadian study shows that the walkability of a person's neighbourhood influences their risk of developing diabetes.

The researchers found that people in neighbourhoods that were easier to walk around were less overweight and less likely to develop diabetes over about a decade of follow-up.

In an editorial accompanying the study in JAMA, Andrew Rundle (Columbia University, New York, USA) and Steven Heymsfield (LSU System, Baton Rouge, Louisiana, USA) say that "urban design for neighborhood walkability is an attractive avenue for public health interventions to reduce the risk of developing obesity or diabetes".

However, they note that social features, such as pedestrian safety and levels of crime "may interact with, or perhaps overwhelm, urban design features that support pedestrian activity."

Researcher Gillian Booth (Institute of St Michael's Hospital, Toronto, Ontario, Canada) and colleagues gauged neighbourhood walkability using a validated method based on population and residential density, walkable destinations and street connectivity. They awarded the neighbourhoods, each containing about 400-700 people, a walkability score between 0 and 100. Scores were generally fairly low; when the team split the neighbourhoods into quintiles of walkability, the median score for the top quintile was just 35.2.

Nonetheless, neighbourhoods in the top quintile had the lowest prevalence of overweight and obesity in 2001, at 43.3% versus 53.5% in the bottom quintile (median score 10.1), after accounting for age, gender, income, and ethnicity.

And the prevalence increased only slightly in the top quintile between baseline and 2012, by a nonsignificant 2.1%, whereas it increased significantly in the bottom three quintiles, eg, by 5.4% in the bottom quintile.

There was a similar trend for the incidence of diabetes, with this decreasing in the top two walkability quintiles over time, compared with no significant change in the least walkable neighbourhoods. For example, the incidence declined from 7.7 to 6.2 per 1000 persons in the top quintile - an absolute reduction of 1.5, compared with a nonsignificant 0.65 reduction in the bottom quintile.

People living in more walkable neighbourhoods made more journeys on foot or by bicycle or public transport than people living in less walkable neighbourhoods did, consequently making fewer journeys by private car.

By contrast, other health behaviours, such as fruit and vegetable consumption, leisure time physical activity and smoking were not associated with neighbourhood walkability. Rundle and Heymsfield note that this serves as a "conceptual negative control", strengthening the overall results.

They say that the study "will make a prominent contribution to the research base that informs the urban design and health policy debates for years to come."

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