A Neighborhood's Affluence May Be Linked to Residents' Risk of Diabetes

People living in a high-poverty area were more likely to be obese and more likely to have diabetes than those in a low-poverty census tract. The researchers characterize the association as "modest but potentially important."

Chief author Jens Ludwig of the University of Chicago stated that, "The effects we see in the study are comparable to what you see from targeted lifestyle interventions or with providing people with medications to prevent the onset of diabetes." "The results show how important our environment is to our health."

The study did not directly prove cause and effect. In addition, it only measured height and weight, and recorded diabetes status, at the end of the study, not at the beginning.

The conclusion comes from about 4,500 mothers living in public housing where at least 40% of the residents in the neighborhood had incomes below the federal poverty level.

From 1994 to 1998, under the U.S. government's Moving to Opportunity program, 1,788 were given housing vouchers that were only good in neighborhoods where the poverty level was less than 10%. Another 1,312 were given vouchers that were good anywhere. Both groups also got counseling on moving. The remaining 1,398 received no special vouchers and no counseling.

More than a decade later, the government did a follow-up study on the women.

Among everyone regarded as obese, with a body-mass index of 30 or higher, the neighborhood made no difference. But among seriously obese women with a BMI of 35 or higher, the voucher for moving into a low-poverty neighborhood seemed to have made a difference; about 31% of those who got the voucher had BMI's of 35 or higher, compared to about 36% who didn't get a voucher.

And 14% of the people who got vouchers that let them move into a better neighborhood were morbidly obese (with a BMI of 40 or higher) compared to 18% of those who did not get a voucher. Furthermore, 16% of women who received a voucher to move into a low-poverty neighborhood were diabetic, versus 20% of those who did not get a low-poverty voucher.

The results are complicated by the fact that only about half of the vouchers for moving into low poverty areas were actually used. In addition, most people in the study ended up living in better neighborhoods anyway. At baseline, the average poverty rate in neighborhoods where the people lived was about 53%; the mean rate had dropped to 33% or below by the 10-year mark.

Ludwig expressed confidence in the results even though measurements of height, weight and diabetes were not done at the start of the study. He said the Department of Housing and Urban Development (HUD) measured 57 other variables and found that the three groups were comparable at the beginning of the study, so it's logical that obesity and diabetic levels were comparable as well.

And the fact that half the people given the special voucher to move into a low-poverty area didn't use it was not a problem "because we've pooled everyone together" and found a difference even when including those who didn't move, he said.

"This was an experiment that was not done by HUD to change obesity and diabetes levels. Seventy-five percent signed up for reasons of safety; they wanted to get away from the crime," said Ludwig. "HUD was thinking, 'We hope this will improve their labor market outcome and get better schools for the kids.' It turns out the effect on diabetes is the same as the best medical interventions we know of. That seems pretty remarkable."

Moving to neighborhoods with less poverty could provide easier access to health care and supermarkets with healthy food, relieve everyday stress that can affect eating habits, and make it easier to find a safe place to exercise, he said. "It could be something as simple as decent sidewalks."

Co-author Dr. Robert Whitaker of Temple University said in a written statement, "Given that diabetes and obesity are associated with a large number of health complications and higher cost for medical care, the findings from this study suggest that improving the environments of low-income urban neighborhoods might improve the duration and quality of life for the residents and lower health care expenditures."

N Engl J Med Nov 26 2011