Longitudinal Associations Between Neighborhood Physical and Social Environments and Incident Type 2 Diabetes Mellitus: The Multi-Ethnic Study of Atherosclerosis (MESA)

Abstract

Importance: Neighborhood environments may influence the risk for developing type 2 diabetes mellitus (T2DM), but, to our knowledge, no longitudinal study has evaluated specific neighborhood exposures.

Objective: To determine whether long-term exposures to neighborhood physical and social environments, including the availability of healthy food and physical activity resources and levels of social cohesion and safety, are associated with incident T2DM during a 10-year period.

Design, setting, and participants: We used data from the Multi-Ethnic Study of Atherosclerosis, a population-based cohort study of adults aged 45 to 84 years at baseline (July 17, 2000, through August 29, 2002). A total of 5124 participants free of T2DM at baseline underwent 5 clinical follow-up examinations from July 17, 2000, through February 4, 2012. Time-varying measurements of neighborhood healthy food and physical activity resources and social environments were linked to individual participant addresses. Neighborhood environments were measured using geographic information system (GIS)- and survey-based methods and combined into a summary score. We estimated hazard ratios (HRs) of incident T2DM associated with cumulative exposure to neighborhood resources using Cox proportional hazards regression models adjusted for age, sex, income, educational level, race/ethnicity, alcohol use, and cigarette smoking. Data were analyzed from December 15, 2013, through September 22, 2014.

Main outcomes and measures: Incident T2DM defined as a fasting glucose level of at least 126 mg/dL or use of insulin or oral antihyperglycemics.

Results: During a median follow-up of 8.9 years (37,394 person-years), 616 of 5124 participants (12.0%) developed T2DM (crude incidence rate, 16.47 [95% CI, 15.22-17.83] per 1000 person-years). In adjusted models, a lower risk for developing T2DM was associated with greater cumulative exposure to indicators of neighborhood healthy food (12%; HR per interquartile range [IQR] increase in summary score, 0.88 [95% CI, 0.79-0.98]) and physical activity resources (21%; HR per IQR increase in summary score, 0.79 [95% CI, 0.71-0.88]), with associations driven primarily by the survey exposure measures. Neighborhood social environment was not associated with incident T2DM (HR per IQR increase in summary score, 0.96 [95% CI, 0.88-1.07]).

Conclusions and relevance: Long-term exposure to residential environments with greater resources to support physical activity and, to a lesser extent, healthy diets was associated with a lower incidence of T2DM, although results varied by measurement method. Modifying neighborhood environments may represent a complementary, population-based approach to prevention of T2DM, although further intervention studies are needed.

Figure. Adjusted Hazard Ratios (HRs) for Type 2 Diabetes Mellitus (T2DM) Incidence Corresponding to an Interquartile Range (IQR) Increase in Exposure to Neighborhood Resources, 2000 to 2012

Model 1 adjusts for baseline age, sex, family history of T2DM, household per capita income, educational level, smoking status, and alcohol use. Model 2 adjusts for all covariates in model 1 and adds neighborhood socioeconomic status. All exposures correspond to cumulative mean exposures over time. An IQR increase in exposure corresponds to the following changes for each exposure: 2.2 for geographic information system (GIS)-based supermarkets and/or fruit and vegetable (FV) markets; 0.6 for survey-based healthy food resources; 2.1 for combined healthy food resources; 3.2 for GIS-based commercial recreational establishments; 0.4 for survey-based physical activity (PA); 1.2 for combined PA; 0.3 for social cohesion; 0.7 for safety; and 2.0 for combined social environment.