Policy Measures Lower Out-of-Pocket Insulin Costs for Medicare Part D Beneficiaries

The proportion of Medicare Part D beneficiaries not receiving the low-income subsidy who paid $35 or less for a 30-day insulin supply increased following the implementation of the Senior Savings Model and the Inflation Reduction Act, while mean out-of-pocket costs declined, according to a research letter recently published in JAMA Network Open.¹

Addressing the Gap in Insulin Affordability Data for Medicare Beneficiaries

CMS introduced the Senior Savings Model in 2021, a voluntary program that capped the out-of-pocket cost of insulin at $35 per month for certain Medicare Advantage and standalone Medicare Part D plans.² The Inflation Reduction Act expanded this benefit to all Medicare beneficiaries enrolled in Part D, effective January 1, 2023.¹

Researchers noted that both initiatives were expected to substantially improve insulin affordability, particularly for those not receiving the low-income subsidy. However, contemporary population-level data assessing changes in insulin out-of-pocket costs remain limited.

To address this gap, the investigators analyzed trends in insulin out-of-pocket costs among Medicare beneficiaries without the low-income subsidy. They used 100% Medicare Part D prescription drug claims from 2019 to 2023 to create 5 annual cohorts, each including Part D beneficiaries with at least 1 insulin claim during the calendar year.

The primary outcome was the out-of-pocket cost for a 30-day equivalent supply of insulin. For each beneficiary, the researchers divided the total annual out-of-pocket insulin cost by the total number of days supplied. They then multiplied this figure by 30 to calculate a 30-day equivalent cost. To account for inflation, all costs were adjusted to 2023 prices using the Consumer Price Index.

The researchers evaluated changes in the mean and distribution of out-of-pocket costs overall and by state of residence. However, they did not conduct statistical testing or report standard errors since the analyses encompassed the entire population of Part D beneficiaries without the low-income subsidy.

Policy Measures Lead to Substantial Declines in Insulin Out-of-Pocket Expenses

The study included 3,795,879 eligible beneficiaries, with a mean age of 70.7 years. The proportion of beneficiaries paying $35 or less for a 30-day equivalent insulin supply increased from 48% to 75% over the study period. Consequently, the mean out-of-pocket cost decreased from $50.87 to $21.98, a 55.8% relative reduction, with large declines occurring after 2020.

Additionally, in 2023, 25.1% of beneficiaries still paid more than $35 for a 30-day equivalent supply, largely due to claims for quantities not prorated to the monthly cap, like $70 for a 45-day supply, for example. Among these nonprorated claims, the researchers noted that 99.9% were for quantities not in multiples of 30 days.

Lastly, the mean out-of-pocket costs fell in all states during the study period. In 2023, the mean out-of-pocket cost for a 30-day equivalent insulin supply ranged from $10.36 in Washington, DC, to $31.09 in Minnesota, with the highest costs observed in rural Midwest states.

Building on Policy Gains to Maximize Affordability

The researchers concluded by acknowledging several of their study’s limitations, including that it did not assess whether health plans raised premiums or restricted coverage in response to insulin out-of-pocket caps. In addition, they calculated out-of-pocket costs from Part D claims, which exclude cash purchases made without insurance. Still, they emphasized the clinical significance of their findings.

“Overall, these results suggest that insulin affordability has substantially improved for Medicare beneficiaries in recent years,” the authors wrote. “Prorating out-of-pocket costs to match the Inflation Reduction Act limit for all insulin quantities may further reduce costs to patients.”

References

1. Fang M, Dun C, Wang D, et al. Trends in insulin out-of-pocket costs among US Medicare beneficiaries. JAMA. Published online March 19, 2026. doi:10.1001/jama.2026.2341
2. Inserro A, Caffrey M. Seniors in certain Part D plans, Medicare Advantage to see insulin costs capped in 2021. AJMC^®. May 26, 2020. Accessed March 23, 2026. https://www.ajmc.com/view/seniors-in-certain-part-d-plans-medicare-advantage-to-see-insulin-costs-capped-in-2021