By Parker Brown, MedPage Today Reviewed by Robert Jasmer, MD for everydayhealth.com
Living in a neighborhood with resources to support exercise and with access to healthy food was associated with a lower incidence of type 2 diabetes, found a new prospective, longitudinal study.
Researchers found that 12 percent of the more than 5,000 people in the study developed diabetes within the average 8.9 years of follow-up. But patients who lived in areas that had access to more physical activity resources had a lower risk, as did those who had access to healthy foods, of developing diabetes.
The social environment of a neighborhood was not associated with the incidence of type 2 diabetes, found the researchers, who were led by Paul Christine, MPH, at the University of Michigan School of Public Health. They published their results today in JAMA Internal Medicine.
“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,” wrote Nancy Adler, PhD, and Aric Prather, PhD — both at the Center for Health and Community at the University of California San Francisco — in an accompanying editorial. “In brief, the risk for type 2 diabetes mellitus is a combination of both person and place, and our national strategies need to understand and intervene across these levels.”
Christine and colleagues also found that environmental resources mattered differently to those with higher and lower incomes. Poorer patients in areas being viewed as having less social activity and as being more dangerous to go outside in were more likely to develop type 2 diabetes. But overall, neighborhood safety and social cohesion were “largely unassociated” with diabetes, according to the authors.
The data were taken from the multi-ethnic study of atherosclerosis (MESA) and included non-institutionalized adults from six different cities. Those with clinical cardiovascular disease were excluded, as were those who had type 2 diabetes at baseline.
Diabetes status was determined by fasting plasma glucose levels at an examination. Information about family history of type 2 diabetes, chronic stress, socioeconomic factors, alcohol consumption, and smoking status was also collected. To determine how healthy the food was and how easily accessible exercise resources were in a particular neighborhood, researchers used two methods.
The first used geographic information system-based measures of access to supermarkets and fruit and vegetable markets for healthy food, and exercise-related facilities like gyms, dance studios, golf courses, racquetball courts, and water activities. As a secondary measure, the researchers used surveys to collect data about availability of healthy foods, walking environment, and social environment. They then calculated the mean of the survey responses within 1 mile of each respondent’s residential address and formed a neighborhood measure.
Neighborhood resources were less available for racial and ethnic minorities, the researchers found. Hispanics, African Americans, those with lower income, poor education, low levels of physical activity, a higher body mass index, and a family history of type 2 diabetes were more likely to develop diabetes.
“Our results suggest that modifying specific features of neighborhood environments, including increasing the availability of healthy foods and physical activity resources, may help to mitigate the risk for T2DM although additional intervention studies with measures of multiple neighborhood features are needed,” wrote Christine and colleagues. “Such approaches may be especially important for addressing disparities in T2DM given the concentration of low-income and minority populations in neighborhoods with fewer health-promoting resources.”
Joel Zonszein, MD, at the Albert Einstein College of Medicine, said the the study was important in establishing that the environment plays a large role in diabetes. “While type 2 diabetes has an important genetic factor, the persistent favorable changes in environment may play a role in the incidence of the disease,” he said in an email to MedPage Today.
Adler and Prather, in their editorial, added that the research is important because the behavioral causes of obesity often take place before the patient even interacts with their physician.
“The behavioral causes of obesity — diet and exercise — are … strongly rooted in factors outside the healthcare system,” they wrote. “Traditional medical treatments alone cannot substantially lower the prevalence and impact of obesity without changes in the obesogenic environment.”
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In the study, access to supermarkets and fruit and vegetable markets was not associated with risk of developing diabetes. Adler and Prather noted that onset of type 2 diabetes wasn’t predicted solely by the geographic information system data, but it was by the survey data. A person’s perception of the availability of food might be more important than just having a supermarket, they said: “Unless the available resources are widely known and viewed as accessible, ‘if you build it, they will come’ may not apply.”
In addition, Adler and Prather noted that precision medicine — which has so far been used mainly to focus on the genomics of tumors for cancer treatment — could be used to treat chronic conditions like type 2 diabetes. “If precision medicine is to fulfill it potential to improve health, it needs to encompass the entire range of determinants of disease onset and progression, ranging from a person’s genetic code to his or her ZIP code,” they wrote.
Limitations of the study include the possibility of residential self-selection, where participants with certain risk profiles choose to live in certain areas. There may also be factors unaccounted for in the study like traffic safety and availability of green spaces. In addition, nearly a quarter of MESAs participants were lost to follow-up by the last examination.
The work was supported by grants from the National Heart, Lung and Blood Institute and from the National Center for Research Resources.
Researchers reported no relevant relationships with industry.
Adler and Prather reported no relevant relationships with industry.