The Affordable Care Act (ACA) provided health insurance for an estimated 1.9 million people with diabetes, according to a newly published study.

In 2009 and 2010, 17 percent of adults who were under age 65 and had diabetes were uninsured. After the ACA took effect, that percentage declined by 12 percentage points and by 27 percentage points among those with low income.

Coverage gains were particularly strong among people whose diabetes was undiagnosed. In 2009 and 2010, approximately one in four adults under age 65 with undiagnosed diabetes lacked health insurance coverage. After the ACA was implemented, the uninsured rate in this group dropped by 17 percentage points to eight percent.

Rebecca Myerson, MPH, PhD, assistant professor of population health sciences at University of Wisconsin School of Medicine and Public Health, was the principal author of the study, which was conducted while she was on the faculty at the School of Pharmacy and Schaeffer Center for Health Policy and Economics at the University of Southern California. The findings were published in the journal Diabetes Care.

The research team analyzed information from 11 years of the National Health and Nutrition Examination Survey, which gathers data that are nationally representative of the civilian population. The biennial survey includes biomarkers, including HbA1c, a measure of blood-sugar control. Using the NHANES data allowed the researchers to identify those with undiagnosed diabetes.

The sample used in the study included 2400 US citizens (ages 26-64) with diabetes, defined as an HbA1c level at or greater than 6.5 percent or a diabetes diagnosis by a health-care professional. Prior studies have found that about one-third of all US adults with diabetes do not know they have it.

“Insurance coverage can change the health trajectory of people with diabetes by providing access to diagnosis and treatment,” said Myerson. “But just as importantly, increasing coverage rates can also enhance health equity, because people with undiagnosed or untreated diabetes disproportionately belong to under-served groups.”

The researchers estimate that, of the 1.9 million people with diabetes who gained coverage under the ACA, 1.2 million had low income (defined in the study as below 138 percent of the federal poverty level).

Myerson has received grant funding from Bristol-Myers Squibb for other research. Two other members of the research team also reported honoraria or research funding from various companies. The team had full access to all of the data in the study.