Residential Urbanicity is Associated with glycosylated hemoglobin levels in Older Adults

Abstract

Introduction:Environmental pollutants have been previously associated with increased risk of diabetes mellitus (DM) and perturbations in glucose homeostasis. Little is known however about how, and to what extent, neighborhood urbanicity may impact biomarkers of glucose control.Methods:We used mixed effects multiple regression models to evaluate neighborhood urbanicity and glycosylated hemoglobin (HbA1c) levels among 4,121 individuals >57 years of age enrolled in the National Social Life, Health, and Aging Project. We also examined for effect modification by race/ethnicity, socioeconomic status, health status, BMI, and age. Secondary analyses examined whether associations were mediated by PM2.5, NO2, and physical activity. Urbanicity measurements were calculated as the percentage of low- and high-intensity residential, and industrial/ commercial/ transportation land use within 1 km of each participants residence, using data obtained from the US Geological Survey National Land Cover Dataset. HbA1c levels were measured from dried blood spots and were log transformed prior to inclusion in models. All models were adjusted for demographic, socioeconomic, health behavior, medical history, and current medications which have been previously shown to affect HbA1c and DM risk.Results:Each IQR increase in surrounding urban landcover was associated with a 1.0% (95% CI 0.1, 1.8) increase in HbA1c levels. In effect modification models, the associations were found to be over four times stronger among Black participants (4.7%, 95% CI: 0.7 -8.9) relative to White participants (0.8%, 95% CI: 0.0, 1.7; Pinteract 0.04). No significant mediation was observed by any investigated variables.Conclusions:In a cohort of older US men and women, neighborhood urbanicity was significantly associated with HbA1c, with significantly larger affects in Black participants. These associations suggest that urbanicity may be an important contributor to perturbed glucose metabolism in older adults.