Environmental factors associated with changes in county-level diabetes prevalence in the United States, 2004-2017

Abstract

BACKGROUND AND AIM: The prevalence of diabetes among adults in the United States (US) has increased steadily in recent years. Although individual risk factors and diagnostic and treatment changes are important, evidence suggests that contextual risk factors have contributed to these increases. We hypothesize that poor environmental quality might also explain increases in diabetes prevalence in the US. METHODS: We obtained age-adjusted estimates of diabetes prevalence among adults from the CDC for all US counties for 2004-2017 and examined changes in these estimates over time within four county strata using the US Department of Agriculture’s Rural Urban Continuum Codes (RUCC) classifications: RUCC1 (metropolitan urbanized), RUCC2 (non-metro urbanized), RUCC3 (less urbanized), and RUCC4 (thinly populated). We obtained estimates of the county-level environmental quality index (EQI) from the US EPA representing 2006-2010, reflecting five domains: air, water, land, sociodemographics, and built environment. Analysis of changes in diabetes prevalence using growth mixture modeling is in progress; we will compare latent classes of county-level diabetes prevalence trajectories with EQI measures. RESULTS:A total of 3,137 counties were included in this analysis (RUCC1 n = 1166, RUCC2 n = 306, RUCC3 n = 1026, RUCC4 n = 639). Mean (SD) percentage change in age-adjusted diabetes prevalence between 2004-2017 was: 6.8 (23)% (RUCC1), 10.8 (25)% (RUCC2), 12.6 (32)% (RUCC3), and 5.4 (34)% (RUCC4); each RUCC strata included counties where diabetes prevalence decreased. Except for RUCC4 (thinly populated) counties, mean EQI values were higher among counties that had a net decrease in diabetes prevalence compared to those with an increase between 2004-2017. CONCLUSIONS:There was substantial heterogeneity in the percent change in age adjusted diabetes prevalence across all RUCC strata between 2004-2017. Environmental quality may be related to this increase. KEYWORDS: environmental epidemiology; obesity and metabolic disorders