Residents' View of Neighborhood Affects Type 2 Diabetes Risk

Marcia Frellick

June 29, 2015

Increasing the availability of healthy food and outlets for physical activity in neighborhoods may help decrease the risk of type 2 diabetes over the long term, new research shows.

The findings may be especially important in narrowing disparities, since large numbers of low-income and minority populations are clustered in neighborhoods lacking such resources, say Paul Christine, MPH, from the department of epidemiology at the University of Michigan, Ann Arbor, and colleagues in their paper, published online June 29 in JAMA Internal Medicine.

The results showed that greater cumulative exposure to physical opportunities — including sports, green space, and gyms — was associated with a 21% lower risk of developing type 2 diabetes over 10 years. Access to healthy foods was linked to a 12% lower risk.

Importantly, resident's perception of their neighborhoods appears to be a key variable, the researchers say.

"Most discussion of diabetes prevention is focused on individuals. Our study points to the need to consider neighborhood environments as potentially useful public-health targets that may complement and strengthen individual-based prevention programs," Mr Christine told Medscape Medical News

Healthcare providers should be aware that patients' lifestyle decisions may be influenced by their neighborhoods, and clinicians and hospital systems should partner with public-health agencies, city planners, and community organizations to ensure that modifying neighborhood environments is part of the diabetes-prevention discussion, he stresses.

Survey Answers Were Most Informative

The study used data from the Multi-Ethnic Study of Atherosclerosis, which followed 5124 subjects ages 45 to 84 who were free of type 2 diabetes at baseline for 10 years. It is the first to examine the longitudinal effects of exposure to healthy foods and physical activity in a large, multiethnic, geographically diverse sample, the authors explain.

During a median follow-up of 8.9 years, 616 of the 5124 participants (12%) developed type 2 diabetes.

The researchers determined access in two ways, and the results varied depending on this. The first calculated geographic density of healthy-food sellers and physical-activity outlets within a one-mile radius of a study participant's home.

The second used survey information in which residents of the community were asked to rate availability of healthy food and walking environment.

After adjustment for confounders, including alcohol and tobacco use, a lower risk of developing type 2 diabetes — defined as a fasting glucose level of at least 126 mg/dL or use of insulin or oral antihyperglycemic agents — was associated with greater cumulative exposure to indicators of neighborhood healthy food (hazard ratio [HR], 0.88) and physical-activity resources (HR, 0.79).

The associations with type 2 diabetes onset were found only with the survey answers, however, and not with the neighborhood environment.

Mr Christine says this indicates that just adding more grocery stores isn't the answer. People have to consider such outlets accessible, which may be affected by factors including cost and convenience.

"That's an area that needs further research," he explained.

The researchers also found that environmental resources were differentially related to diabetes risk for individuals with higher vs lower incomes.

Clues to Which Activities Will Make a Difference, and Where and When

In an invited commentary, Nancy Adler, PhD, and Aric Prather, PhD, of the Center for Health and Community at University of California, San Francisco, say "although we do not yet know what elements of neighborhoods are most essential for generating better health, these researchers provide important clues about which elements have an effect and for whom."

This includes the "notable finding" that type 2 diabetes wasn't predicted by counts of the density of food stores and recreational facilities, but rather by the shared perceptions of people in the community regarding the availability of healthy food and nearby places to be active, they observe.

This is consistent with other studies that have shown relatively weak associations between the proximity of supermarkets and outcomes such as body mass index (BMI) and fruit and vegetable consumption, they state.

A second "informative" discovery was the fact that low-income participants living in areas viewed as having less social cohesion and being less safe for walking were more likely to develop diabetes.

Such views were less relevant for those with higher incomes, suggesting they need worry less about the social climate of the areas they live in relation to physical activity, because they can afford to join fitness centers, for example.

More study is therefore needed on which activity resources will be most effective and who would use them and at what times.

"Building more facilities in neighborhoods that lack them is a component of an overall strategy to address the national rise in obesity, but this strategy needs to be informed by an understanding of when such facilities are actually used and the characteristics of the individuals who use them," they conclude .

This research was supported by the National Institutes of Health and the National Center for Research Resources. The study and commentary authors report no relevant financial relationships.

JAMA Intern Med. Published online June 29, 2015. Article, Editorial

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