Social environment and year of birth influence type 1 diabetes risk for African-American and Latino children.

OBJECTIVE: Credible epidemiological data, primarily from European-origin populations, indicate that environmental factors play an important role in the incidence of type 1 diabetes. RESEARCH DESIGN AND METHODS: A population-based registry of incident cases of type 1 diabetes among African-American and Latino children in Chicago was used to explore the influence of individual and neighborhood characteristics on diabetes risk. New cases of insulin-treated diabetes in African-American and Latino Chicagoans aged 0-17 years for 1985-1990 (n = 400) were assigned to one of 77 community areas based on street address. Census tables provided denominators, median household income, percentage of adults > or = 25 years old who had completed high school and college, and a crowding variable for each community area individual-level data were birth cohort, sex, and ethnicity. Outcomes in Poisson regression were sex-, ethnic-, and birth cohort-specific incidence rates. RESULTS: Significant univariate associations between diabetes risk and ethnicity, birth cohort, crowding, and the percentage of adults in each community area who had completed high school and college were observed. African-Americans had a relative risk (RR) of 1.42 (95% CI, 1.14-1.76) compared with Latinos. Risk varied significantly by birth cohort in both ethnic groups. For every 10% increase in the proportion of adults who completed college, the RR for diabetes increased by 25% (RR, 1.25 [95% CI, 1.09-1.44]). Social class variables were significant determinants of risk for African Americans, but not for Latinos. CONCLUSIONS: The strong birth cohort and social class associations observed in this study implicate an infectious exposure linked with age.