Little is known about environmental determinants of type 2 diabetes. The authors hypothesized that insulin resistance is positively related to distance to a wealthy area and to local neighborhood poverty. Data were derived from The Multi-Ethnic Study of Atherosclerosis, a study of adults aged 45-84 years in six US locales, and the 2000 US Census. The homeostasis model assessment (HOMA) index was used to measure insulin resistance. Linear regression was used to estimate associations between area characteristics and insulin resistance after adjustment for age, sex, income, education, and race/ethnicity and for the potential mediators diet, physical activity, and body mass index (n = 4,821). Among persons not treated for diabetes, distance to a wealthy area was associated with HOMA independent of local poverty and person-level covariates: per 4.4-km change, the relative increase in HOMA was 13% (95% confidence interval: 7%, 19%), similar to the effect of a body mass index increase of 1.7 kg/m(2) on HOMA. This association was reduced after adjustment for physical activity, diet, and body mass index (relative increase = 9%, 95% confidence interval: 3%, 15%). Local neighborhood poverty was also positively, but more weakly associated with insulin resistance, with no association after adjustment for race/ethnicity. This study shows that proximity to resources in high-income areas is related to insulin resistance.