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.