Evidence of a relationship between the built environment and obesity risk has been growing but few studies have looked at the relationship between the built environment and insulin resistance (IR), which is related to type 2 diabetes, which is closely linked to obesity. The purpose of this study was to examine the relationship between characteristics of children's neighborhood built environment and IR using accurate laboratory measures that take into account fat distribution and body composition and weight status.
This study utilized pre-existing data from studies conducted at the University of Southern California Childhood Obesity Research Center linked to a database of food and physical activity (PA) environment characteristics, and community-level sociocultural characteristics. A decade (2001-2011) of archived data from six studies of non-diabetic, Hispanic youth without IR in the Los Angeles area contributed 453 participants for analysis, aged 8–18 years. These data were paired with neighborhood built environment characteristics and 2000 Census data. The food environment was measured by the density of six common fast-food chains and convenience stores within certain distances from the home. The PA environment was characterized by acres of park space within specific buffer zones around the home. Two-mile walking distance buffers were built around participants' homes. Dual x-ray absorptiometry and waist circumference were used to measure body composition and fat distribution. Although Hispanic ethnicity per se may not contribute directly to obesity or diabetes, Hispanic communities often live in low-SES neighborhoods. Residence in these communities has been shown to increases risk for obesity and related disorders. Also, acculturation, for example measured by the absence of a family member who speaks English well (linguistic isolation) may also be predictive of risk of developing a metabolic disorder. The relationship between acculturation and the development of metabolic disorders is not well-understood.
The authors hypothesized that (1) increased access to fast-food would predict increased IR, (2) increased access to convenience stores would predict increased IR, (3) increased access to parks would predict decreased IR, (4) increased walkability would predict decreased IR, and (5) neighborhood-level acculturation would predict increased IR. Multiple regression analyses for each gender, and adjusted for various neighborhood and sociocultural variables, were used to measure the ability of park space, food access, walkability, and neighborhood acculturation to predict IR.
Even controlling for the obesity measures of body composition and fact distribution, greater fast-food restaurant density was related to higher IR. Specific findings differed by gender. For boys, fast food density within 1 mile and more acres of park space within 2 miles, as well as neighborhood linguistic isolation, were related to lower IR. For girls, park space within a ½ mile buffer was associated with lower IR, but linguistic isolation was related to increased IR. For girls, there was also a significant interaction between waist circumference and linguistic isolation suggesting that greater linguistic isolation is associated with higher IR, but only among girls with lower waist circumferences. The authors suggest that boys are more likely to have freedom to travel around their communities than girls, giving them increased access to fast food as well as to parks farther away from home. Girls' more limited mobility explains the effect of park space close to home on IR but not park space farther from home. The authors conclude that reducing access to fast food and increasing public park space could help reduce IR risk and type 2 diabetes, but effects may vary by gender.
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