Study Evaluates Impact of Food Environments on T2D Risk

Neighborhood food environment measures are associated with type 2 diabetes (T2D) among US veterans living in multiple community types, according to results of a national cohort study. Findings, published in JAMA Network Open, also suggest food environments serve as potential avenues for action to address the burden of diabetes, researchers wrote.

Since the late 1990s, diabetes risk has increased in all regions of the United States. However, research has revealed “substantial geographical disparities in diabetes prevalence and incidence,” while “county-level analyses have highlighted age-adjusted prevalence of diabetes ranging from 1.5% (mostly counties in the West) to as high as 33% in others (mostly counties in the Southeast),” authors explained.

Previous studies on limited geographical regions have also showed neighborhood resources, like suitability for physical activity and availability of healthy food, also impact diabetes rates.

Using data from the CDC’s Diabetes Location, Environmental Attributes, and Disparities (Diabetes LEAD) network, investigators explored the association between presence of fast-food establishments and supermarkets on T2D incidence among US veterans. To generate neighborhood food environment measures, the researchers devised 5-year mean counts of fast-food restaurants and supermarkets relative to other food outlets at baseline.

“The association between food environment and time to incident diabetes was examined using piecewise exponential models with 2-year interval of person-time and county-level random effects stratifying by community types,” they wrote.

Participant information was gleaned from the Veteran’s Affairs electronic health record, and “all baseline neighborhood-level attributes were defined at cohort entry date.” In addition, relative food environment measures were identified, and “all US Census tracts were categorized by the Diabetes LEAD network into 1 of 4 community types using a modified measure of the 2010 Rural-Urban Commuting Area: high-density urban (HDU), low-density urban (LDU), suburban or small town (suburban), and rural,” the authors wrote.

They included those enrolled in the program between 2008 and 2016 and followed up with veterans through 2018, for a median (IQR) follow-up time of 5.5 (2.6-9.8) person-years.

Over 4 million individuals were included in the final analysis with a mean (SD) age of 59.4 (17.2) years at enrollment. At baseline, no participants had diabetes. The majority of participants were male, and those living in rural communities tended to be slightly older than those in urban communities. Most individuals were non-Hispanic White and either had a disability or were low income.

A total of 13.2% (539,369 participants) met T2D criteria throughout the follow-up window, with cumulative incidence highest among those aged 60 to 79 years.

Analyses revealed:

• The relative density of fast-food restaurants was positively associated with a modestly increased risk of T2D in all community types
• The adjusted HR was 1.01 (95% CI, 1.00-1.02) in HDU communities, 1.01 (95% CI, 1.01-1.01) in LDU communities, 1.02 (95% CI, 1.01-1.03) in suburban communities, and 1.01 (95% CI, 1.01-1.02) in rural communities
• The relative density of supermarkets was associated with lower T2D risk only in suburban (aHR, 0.97; 95% CI, 0.96-0.99) and rural (aHR, 0.99; 95% CI, 0.98-0.99) communities
• Non-Hispanic Black adults had the highest incidence of type 2 diabetes (16.9%) compared with other racial and ethnic groups
• Adults with disability and those with low income but no disability had higher incidence than those with neither disability nor low income
• The mean proportion of fast-food restaurants compared with other food outlets was 26% (14%) in HDU communities, 31% (13%) in LDU communities, 32% (10%) in suburban communities, and 29% (15%) in rural communities
• No significant association was found between supermarket availability and T2D incidence in urban communities

The esearchers hypothesized the lack of association between T2D and supermarket availability in urban communities could be due to public transportation and cars, which could increase access to supermarkets, noting “interventions targeting the placement or zoning of supermarkets may be more appropriate in suburban and rural communities.”

Furthermore, policies restricting siting of fast-food restaurants and healthy beverage default laws could help reduce T2D incidence in all community types, although these measures may be more beneficial in urban areas.

The observational nature of this study and the lack of data on residual lifestyle confounders mark limitation to the analysis. Findings may also not be generalizable to nonveteran populations.

“Tailored interventions targeting availability of supermarkets may be more appropriate in suburban and rural communities than urban communities, whereas restrictions on fast-food restaurants could possibly help in all community types,” the authors concluded.

“These actions, combined with increasing awareness of the risk of T2D and the importance of healthy diet intake, might be associated with a decrease in the burden of T2D among adults in the United States.”

Reference

Kanchi R, Lopez P, Rummo PE, et al. Longitudinal analysis of neighborhood food environment and diabetes risk in the veterans administration diabetes risk cohort. JAMA Netw Open. Published online October 29, 2021. doi:10.1001/jamanetworkopen.2021.30789