Low-income adults in the U.S. likely benefited if their states expanded Medicaid in 2014 under the Affordable Care Act, suggests a new study.

Researchers found increased rates of insurance coverage, health care use and chronic disease diagnoses among low-income adults in states that expanded access to the government-funded health insurance program.

“It looks like there is better medical care for these adults,” said lead author Laura Wherry, of the David Geffen School of Medicine at the University of California, Los Angeles.

A key provision of the Affordable Care Act (ACA), sometimes referred to as Obamacare, was to force states to expand their Medicaid programs by 2014. But with a Supreme Court decision allowing states to opt out of the expansion, only 26 states actually expanded their Medicaid programs.

For the new study, the researchers analyzed 2010-2014 survey data collected from low-income U.S. adults ages 19 to 64. In the pre-expansion era, from 2010-2013, about 33 percent of people had no insurance in states that ultimately expanded Medicaid, compared to about 42 percent in states that opted out of expansion. In 2014, those rates fell to about 18 percent in states that expanded Medicaid and about 34 percent in states that didn’t.

Overall, the uninsured rate fell by about 7 percentage points more in states that expanded Medicaid than in those that didn’t. States with expanded Medicaid coverage also had a larger increase in the proportion of people who thought their insurance coverage improved over the previous year.

Additionally, there was evidence that people in states with expanded Medicaid programs were using their coverage, because they had larger increases in interactions with general physicians and overnight hospital stays. There were also more diagnoses of diabetes and high cholesterol in states with expanded Medicaid programs.

Gaining insurance likely leads to more screening for these conditions, and more diagnoses may lead to early treatment and important downstream health effects, Dr. Jeffrey Kullgren wrote in an editorial accompanying the new study.

The new study shows what’s happening in states that expand Medicaid and “what is foregone by states that reject the ACA’s opportunity to expand Medicaid,” write Kullgren, of the University of Michigan Medical School and he Veterans Affairs Ann Arbor Health System.

While the new study did not show that people felt healthier in expanded-Medicaid states, Wherry said it may be too early to see changes in that measure. “I think long-term follow up will be very important,” she said.

The results help confirm the value of the ACA for people who obtain this coverage, said John McDonough, who worked on the ACA but was not involved with the new study. He said the new findings likely won’t convince reluctant states to expand their Medicaid programs, however.

“It’s not about evidence at this point,” said McDonough, who is a professor at the Harvard T.H. Chan School of Public Health in Boston. “It’s about a political fear over Obamacare that at this point is not influenceable by meaningful evidence.”