Diabetes Studies Reveal How Insurance and Ethnicity Can Affect Outcomes

Two recent studies from researchers at the USC Leonard D. Schaeffer Center for Health Policy & Economics shed light on the impact of diabetes for uninsured, recently insured, and underserved patients, with a close look at race and ethnicity as factors in the disease and its complications.

“Diabetes is a top cause of death in the United States, affects 18 million non-elderly adults, and accounts for over $300 billion in costs annually. Studies have suggested that insurance coverage can increase diabetes diagnosis and treatment, setting patients on the path to manage the disease.” said Rebecca Myerson, a researcher at the USC Schaeffer Center for Health Policy & Economics and an assistant professor at the University of Wisconsin. “Yet, many people with diabetes remain uninsured and suffer from preventable complications.” Myerson was a co-author of both studies and lead researcher on the study published in Diabetes Care.

Insurance Impacts Diabetes Trajectory

The Affordable Care Act (ACA), signed into law in 2010, significantly reduced the number of uninsured Americans. For diabetes patients alone, it expanded coverage for nearly 2 million people, more than half of them low-income.

A USC Schaeffer Center study published in Diabetes Care in September looked at the impact of the ACA on patients with diabetes.

The study found that, in 2009 and 2010, 17 percent of all adults under age 65 who had diabetes were uninsured. After the ACA took effect, that number declined to 5 percent (12 percentage points).  Among low income adults with diabetes, 33 percent were uninsured before the ACA and 6 percent were uninsured after – a reduction of 27 percentage points. In all, an additional 1.9 million people with diabetes- more than half of whom were low-income – gained insurance coverage after the ACA took effect.

The CDC estimates that nearly 25 percent of the 30.3 million people in the U.S. with diabetes are undiagnosed. The Diabetes Care study found that, in 2009 and 2010, about 1 in 4 adults under age 65 with undiagnosed diabetes lacked health insurance coverage and that, after ACA implementation, the uninsured rate among the undiagnosed dropped by 17 percentage points, to just 8 percent.

This study was the first to demonstrate gains in insurance coverage under the ACA among patients with both diagnosed and undiagnosed diabetes.

“Many people who have diabetes don’t know it,” says John Romley, associate professor at the USC School of Pharmacy and an economist at the Schaeffer Center, and one of the study’s co-authors. “Access to insurance coverage through the Affordable Care Act has helped this underserved population get diagnosed and access the care it needs.”

Gains in coverage for diagnosed and undiagnosed patients could improve outcomes and health equity — particularly for low-income patients, as insurance coverage can change the health trajectory of diabetes patients by facilitating timely diagnosis and reducing the financial strain of utilizing care.

In addition to Romley and Myerson, co-authors included Schaeffer Center researchers Tommy Chiou, Anne L. Peters and Director Dana Goldman.

Tracking Trends in Diabetes Complications

Given the improvements in therapies and understanding about the disease, most complications from diabetes can be managed reasonably effectively with proper knowledge and access to care. As such, diabetes-related complication rates have declined significantly over the past two decades. However, it is unclear how complication rates have changed across different racial and ethnic groups.

A study, published in September 2019 in the Journal of General Internal Medicine, and led by USC Schaeffer Center experts found significant racial and ethnic disparities in diabetes complications—a finding that illustrates the complex nature of access to care and disease management within the diabetes population.

Their analysis showed that cardiovascular complications, while still high relative to other populations, have declined among white patients. In contrast, rates of renal complications have increased among white patients. Black and Hispanic patients experience higher rates of renal complications but lower rates of cardiovascular complications compared to whites.

Their finding of higher rates of cardiovascular complications among whites contradict the broader literature that has found that minority patients experience worse intermediate outcomes and cardiovascular risk factors. One explanation is that patients from different racial or ethnic groups have different probabilities of receiving a complication diagnosis, due to provider behavior or healthcare access.

“Documented improvements on a national level might not hold up when trends are evaluated by race or ethnicity,” says Goldman, the Leonard D. Schaeffer Director’s Chair at the USC Schaeffer Center. Adding, “when it comes to diabetes, primary and secondary prevention is the key to better health and lower costs.”

The findings highlight the importance of considering race and ethnicity when examining trends to understand how improvements are distributed and to identify opportunities for improving care for diabetes patient populations, note the researchers.

In addition to Goldman, co-authors included Chiou, Myerson, Romley and Matthew Kahn of USC and Yusuke Tsugawa of UCLA.