A New Study Suggests Medicare’s Insulin Cap Is Helping. Why Many Americans Still Pay More.

For many people on Medicare, the current $35 insulin cap appears to be doing what it was meant to do: lower out-of-pocket costs and make insulin a little easier to use as prescribed. But the new research does not mean insulin affordability problems are solved in the United States.

A study published April 6 in JAMA Internal Medicine found that after Medicare’s insulin cap took effect, beneficiaries with type 2 diabetes paid less out of pocket, used slightly more insulin, and had a small improvement in average blood sugar control. At the same time, the study also found a modest rise in severe hypoglycemia events, and it was not designed to show exactly why that happened.

The practical takeaway is twofold. If you have Medicare, it is worth knowing whether your insulin is covered under Part B or Part D and what supplies may still cost extra. If you are not on Medicare, your costs may still depend heavily on your insurance plan, your state, and whether you are insured at all.

What the new study actually looked at

This was not a randomized clinical trial. It was an observational cohort study that used interrupted time-series analysis, a method researchers use to look at what changes after a policy takes effect.

The researchers analyzed claims data from about 4.8 million Medicare Part D beneficiaries with type 2 diabetes from 2019 through 2023. They also had linked electronic health record data for a smaller subgroup, which let them look at A1c, a common measure of average blood sugar over the previous few months.

The timeline matters. Some Medicare beneficiaries began getting a $35 monthly cap in 2021, and the cap expanded to all Medicare beneficiaries in 2023.

What the study found in plain language

The biggest change was cost. Average quarterly out-of-pocket insulin spending fell by about $48 after the 2021 change and by nearly another $59 after the broader 2023 expansion, according to the study.

Insulin use also rose slightly. Average daily insulin use increased by 0.23 units in 2023. In the subgroup with linked medical records, average A1c fell by 0.06 percentage points after 2023.

Those are real changes, but they are modest. This was not a dramatic transformation in blood sugar control. Still, even small shifts can matter when a policy affects millions of people.

The study also found modest increases in severe hypoglycemia events, meaning episodes of dangerously low blood sugar that led to an emergency department visit or hospitalization. The paper shows that this happened alongside the cap, but it cannot prove the cap caused it, and it cannot tell readers exactly what drove the increase.

What the study cannot prove

Because this was an observational study, it can show associations after a policy change, not definitive cause and effect. Other changes in diabetes care, prescribing, or patient behavior over time could also have influenced the results.

The findings also should not be stretched too far. The study focused on Medicare beneficiaries with type 2 diabetes. That means it does not automatically tell us what happened for younger adults, people with private insurance, uninsured patients, or everyone with type 1 diabetes.

There is another important limitation: the A1c analysis came from a subset of about 207,000 people with linked records, not from the full 4.8 million-person study population.

How Medicare’s $35 insulin cap works now

According to Medicare, covered insulin under both Part B and Part D is capped at no more than $35 for a one-month supply, and insulin is not subject to the deductible.

But coverage depends on how you get the insulin. Part B generally covers insulin used with certain durable insulin pumps. Part D generally covers injected insulin, inhaled insulin, and insulin used with pumps that are not covered as durable medical equipment.

This is where some confusion and extra costs can still show up. Medicare says some insulin-related supplies can still cost extra depending on how your coverage works. Under Part B, for example, syringes, needles, alcohol swabs, and gauze are not covered the same way as insulin itself, and some people may end up paying for those items unless they also have Part D coverage for them.

So even with the cap, Medicare does not make every part of diabetes care inexpensive. Test strips, pumps, sensors, office visits, and other supplies or services can still affect what people pay overall.

Why this matters beyond Medicare

This is not a niche issue. The CDC’s National Diabetes Statistics Report says 40.1 million people in the United States had diagnosed or undiagnosed diabetes in 2023.

Outside Medicare, insulin protections are much less uniform. Reporting from the Associated Press notes that some people with private insurance pay little or nothing for insulin, while others still pay hundreds of dollars a month, often on top of costs for pumps, glucose sensors, and other supplies.

That uneven picture helps explain why insulin affordability remains a live policy issue even after Medicare’s cap took effect.

What the INSULIN Act of 2026 would do, if it becomes law

A newly introduced Senate bill, the INSULIN Act of 2026, is aimed at people outside Medicare. Under the bill text, commercial-market protections would start with plan years beginning on or after January 1, 2027.

The bill would require group health plans and individual-market coverage to include selected insulin products without a deductible and to limit cost sharing for a 30-day supply. For plan years beginning before January 1, 2028, that limit would be $35. After that, the bill would generally set the patient cost at the lower of $35 or 25% of the negotiated price for selected products.

That detail matters. The bill is written around selected insulin products, not every insulin product on the market, and the text also leaves room for different rules outside a plan’s network.

The measure would also create a five-year pilot grant program for 10 states to help uninsured people get affordable insulin. But as of April 16, 2026, this is still only an introduced bill. It has not passed Congress, and the Associated Press reports that it still faces legislative hurdles.

Professional groups including the American Diabetes Association have welcomed the proposal, but endorsements do not change the fact that patients outside Medicare do not yet have a new federal cap in place.

What this means for readers

If you have Medicare, the most useful next step is practical: check whether your insulin is covered under Part B or Part D, and ask what related supplies are billed separately.

If you have private insurance, do not assume Medicare’s $35 cap applies to you. Your actual cost may depend on your employer’s plan, whether your coverage is state-regulated, which insulin product you use, and whether your plan has separate cost-sharing rules for devices or supplies.

If you are uninsured, this new study offers encouraging evidence that lower cost-sharing can help people get insulin more consistently, but it does not create new protections for you on its own.

The broader lesson is promising but limited: lowering insulin cost-sharing appears to help many Medicare beneficiaries, yet insurance design, supply costs, and the gaps outside Medicare still shape whether insulin is truly affordable.

Sources

This article is for general informational purposes only and is not medical advice. Research findings can be early, limited, or subject to change as new evidence emerges. For personal guidance, diagnosis, or treatment, consult a licensed clinician. For current outbreak or public health guidance, follow your local health department, the CDC, or another relevant public health authority.