Effects of historic redlining persist to elevate risk of death from diabetes

A recent study investigated the effects of historic residential redlining practices on current health outcomes, focusing on death rates from diabetes and premature death due to diabetes. The study showed significantly worse health outcomes in those who lived in “redlined” areas that were previously graded as less desirable, compared to those who did not, with this negative impact on health persisting for decades. Formalized in 1934 by the Federal Housing Administration and prohibited later in 1968, residential redlining was the systemic practice of denying various services, such as credit access and insurance, to residents of neighborhoods—populated primarily by racial and ethnic minority groups—that were graded as “declining” and “hazardous” in maps created by the Home Owners’ Loan Corporation (HOLC). Recent data show persistent effects of structural racism and inequities, such as health, preterm birth, and COVID-19 outcomes.

In new research, scientists sought to determine whether people with chronic medical needs and high medical cost burden, such as people with diabetes, are disproportionately and negatively impacted by historic redlining. Their analysis combined three sets of data—a digitized copy of the HOLC map of Seattle, Washington; census data; and data on mortality rate and years of life lost (an estimate of the average years a person would have lived if they had not died prematurely). They found that mortality rate and years of life lost in general were significantly higher in areas with exposure to worse HOLC grading, showing clinically meaningful differences in health outcomes. However, these differences were much bigger when they examined mortality and years of life lost specifically due to diabetes, showing an approximately 50 percent increase in the rate of diabetes mortality in areas with a 1-unit-higher HOLC grade (e.g., those with a “hazardous” rather than a “declining” grade); similar results were observed for years of life lost. Results also showed persistence of these differences over the course of 25 years from 1990 to 2014, even though redlining was formally prohibited in 1968.

Current residents in areas with previous exposure to redlining are more likely to experience social risk factors such as poverty, discrimination, and poor educational attainment and employment opportunities. While this study does not establish redlining as a direct cause of increased diabetes mortality, it is the first study to show that redlining, as a surrogate for structural racism, can be a critical link between structural racism and diabetes disparities. It also highlights the important role that our living environment and social factors play in health and diabetes care, while underscoring the urgent need to identify and implement targeted interventions that will stop perpetuating inequities in order to close the gap on diabetes health disparities.