Mapping Census Tract Clusters of Type 2 Diabetes in a Primary Care Population

PEER REVIEWED

Diabetes and prediabetes prevalence across 2 diagnostic criteria is substantial in the Chicago community area of Belmont-Craigin for this patient population. In this neighborhood, ICD-9 and ICD-10 diagnostic diabetes cluster cores correspond to areas of high diabetes prevalence, determined by measuring HbA1c levels, with neighboring tracts often characterized as prediabetes hot spots. Isolated tract outliers of diabetes hot spots occur in Austin, Portage Park, and Irving Park. Isolated cold spots determined by using ICD codes occur in Avondale, Logan Square, and Humboldt Park; however, these areas also neighbor tracts of high diabetes prevalence determined by using measured HbA1c levels. Humboldt Park, which contains the health center, also has areas of high diabetes and prediabetes prevalence, determined by using ICD codes and measures of HbA1c. Consistent cold spots of low diabetes incidence are farthest from the health center, on the west side of the service area, in Austin and Montclare.

This map shows areas with significantly high and significantly low prevalence of diabetes and prediabetes in a health center population in Chicago. Prevalence was determined by ICD (International Classification of Diseases) codes and measured hemoglobin A1_c (HbA_1c). The map highlights regional clusters and isolated areas of diabetes prevalence that could be targeted with interventions to improve health outcomes. Diagnoses determined by ICD codes are shown in colors as hot and cold spot cluster cores corresponding to “high–high” (HH) and “low–low” (LL) LISA (local indicator of spatial autocorrelation) statistics, where selected census tracts and neighboring tracts both have high rates (HH) or both have low rates (LL) of diabetes. Hot spot outliers have high diabetes rates compared with neighboring tracts (“high–low” [HL]), whereas cold spot outliers have low diabetes rates compared with neighboring tracts (“low–high” [LH]). Hot spots of prediabetes and diabetes determined by measured HbA_1c levels are also shown. LISA significance set at P < .05. Supermarket data are from Kolak et al (1). Census tract and community area boundary data are from the Chicago Data Portal (2,3). Basemap imagery is from OpenStreetMap, Leaflet, and Carto.

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