Study: Medicare insulin cap cut costs, raised use for high-cost patients
A JAMA analysis found the $35 Medicare insulin cap reduced out-of-pocket costs, with use gains concentrated among patients who had paid the most.
By Tom Brennan · Health & Medicine Correspondent
3 min read
The Inflation Reduction Act’s $35 monthly insulin cap for Medicare beneficiaries lowered what patients paid and was linked to better insulin use among those who had faced the steepest bills, according to a study published in JAMA. The findings suggest the policy helped some patients with diabetes, though researchers said its reach was limited because many Medicare insulin users already had relatively low costs.
Researchers from Emory University, the University of Southern California and the University of Wisconsin–Madison examined insulin spending and use after the cap began in 2023. According to JAMA, the analysis covered more than 2.8 million Medicare Part D beneficiaries who used insulin.
The team compared costs per 30-day insulin supply, prescription fills, adherence and persistence before and after the policy took effect. The study found that out-of-pocket insulin costs became lower and less volatile under the cap; before the policy, some beneficiaries could see insulin costs double within the same calendar year, according to the researchers.
Across the full group studied, out-of-pocket insulin spending fell by about $5 for each 30-day supply, or roughly 21%, according to JAMA. The largest change in insulin use appeared among beneficiaries whose pre-policy costs were high.
For about 250,000 people who had been paying at least $58 for a 30-day insulin supply before the cap, insulin fills rose 8%, according to the study. The share of days covered by insulin also increased 5% in that higher-cost group.
The researchers said the cap affected only a relatively small portion of Medicare insulin users because Part D beneficiaries are already insured and many had support from other programs. According to the study, just 13% of insulin fills in 2021 and 2022 would have been above the $35 limit.
JAMA reported that many insulin users in Medicare had already benefited from affordability efforts such as Medicare’s Senior Savings Model or the Low-Income Subsidy Program. The people who gained most from the cap were more often non-Hispanic white, male, ages 65 to 75, covered by fee-for-service insurance and less likely to live in an urban area, according to the researchers.
The study authors linked the adherence gains among high-cost patients to a broader concern in diabetes care: when patients skip insulin to save money, they can face avoidable and potentially life-threatening health problems. The authors said the findings point to the need for further policies aimed at insulin affordability.
Rebecca Myerson, an associate professor of health policy and management at Emory University’s Rollins School of Public Health, said patients with high insulin costs improved adherence after the cap, which suggests cost had been leading some to skip doses. She said future caps would have the greatest effect if they reached people with high out-of-pocket costs, including uninsured patients.
Dana Goldman, a co-author and founding director of the USC Schaeffer Institute for Public Policy & Government Service, said reducing patients’ out-of-pocket costs is a policy tool that can support medication use.
The IQVIA Institute estimated that a nationwide $35 cap covering all insulin prescriptions would have saved U.S. insulin users $170 million in out-of-pocket costs in 2024, according to data cited by Emory University.
This story draws on original reporting from Medical Xpress.