The Chicago Childhood Diabetes Registry is a city-wide registry of cases of diabetes in youth aged 0–17 years in Chicago, Illinois. Youth included in the registry meet the following criteria: 1) diagnosis of diabetes based on ICD-9 codes 250.00–250.91, 2) diagnosis on or after 1 January 1985, and 3) diabetes not secondary to another condition. Youth are classified as non–type 1 diabetic if there was a diagnosis or other evidence of type 2 diabetes, such as type 2 diabetes–like clinical course, treatment with pills or no medications, obesity at diagnosis, polycystic ovary syndrome, or acanthosis nigricans (10). Over the study period (1 January 1994 through 31 December 2003), 1,252 patients, representing 92% of registered cases, had complete address and ethnic identity information to be included in the current analysis.

An income diversity index, developed by the Metro Chicago Information Center, was used to contextualize neighborhood socioeconomic characteristics. Household income data collected from the U.S. Census between 1970 and 2000 were used to categorize neighborhoods as stable diversity, emerging low income, emerging high income, desertification, and emerging bipolarity (11). Briefly, stable-diversity neighborhoods consist of 19 neighborhoods that have maintained a socioeconomically diverse population between 1970 and 2000. Emerging low-income neighborhoods (n = 11) have experienced a loss of high-income families, while the reverse has occurred with emerging high-income neighborhoods (n = 21), where the majority of low-income families has decreased. Desertification neighborhoods (n = 11) show patterns of entrenched levels of poverty with a predominantly African American population. Finally, emerging bipolarity neighborhoods (n = 15) show an increase in both high- and low-income residents.

Year 2000 census counts of children aged 0–17 for each of Chicago's 77 community areas (i.e., neighborhoods) were used to provide denominators for calculating incidence rates. Stable-diversity neighborhoods were used as the referent group for Poisson regression analyses using SAS release 8.02 (SAS Institute, Cary, NC).

Compared with stable-diversity neighborhoods, significant associations for type 1 diabetes were found for male subjects in emerging low-income neighborhoods (relative risk 0.45 [95% CI 0.32–0.64]) and emerging high-income neighborhoods (0.75 [0.57–0.99]). For female subjects, emerging low-income, emerging bipolarity, and emerging high-income neighborhoods were found to be protective (0.61 [0.45–0.84]; 0.74 [0.55–0.99]; 0.71 [0.53–0.95]) for type 1 diabetes (Table 1). For non–type 1 diabetes, male subjects residing in emerging low-income neighborhoods were at 38% lower risk (0.62 [0.39–0.99]) (Table 1).

Children aged 0–9 years residing in emerging low-income neighborhoods were at 44% lower risk (0.56 [95% CI 0.36–0.90]) for type 1 diabetes compared with children in stable-diversity neighborhoods. Youth aged 10–17 years residing in desertification (1.38 [1.02–1.87]) and emerging high-income neighborhoods (1.52 [1.17–1.98]), however, were at higher risk for type 1 diabetes (Table 1). For older youth residing in desertification neighborhoods, there was also higher risk for non–type 1 diabetes (1.47 [1.09–1.99]) compared with those from stable-diversity neighborhoods.

Hispanic youth residing in emerging bipolarity neighborhoods had increased risk for both type 1 diabetes (relative risk 1.78 [95% CI 1.78–2.73]) and non–type 1 diabetes (2.15 [1.23–3.77]) (Table 1). Hispanics residing in emerging high-income neighborhoods were also found to have higher risk for non–type 1 diabetes (2.05 [1.15–3.67]). However, in emerging low-income neighborhoods, only non-Hispanic white youth were at higher risk for both type 1 diabetes (2.00 [1.07–3.74]) and non–type 1 diabetes (3.09 [1.07–8.89]) compared with youth in stable-diversity neighborhoods.