Medicare Part D covers injectable insulin that you administer with pens, syringes, or disposable pumps, as well as inhaled insulin. Every Part D plan must cap your cost at $35 per one-month supply for each covered insulin product, and you don’t have to meet your annual deductible before that price kicks in.
What Part D Covers vs. Part B
The dividing line is simple: if you use a traditional, durable insulin pump, your insulin falls under Part B as part of the durable medical equipment benefit. Everything else goes through Part D. Specifically, Part D covers injectable insulin delivered by vials and syringes, insulin pens, needle-free injectors, and disposable pump systems. Inhaled insulin is also a Part D benefit.
Part B does not cover insulin pens or any injection supplies like needles, syringes, alcohol swabs, or gauze. Those items are all Part D territory when used for insulin injections. Some Part D plans also cover the disposable pump devices themselves, not just the insulin that goes in them.
The $35 Monthly Cap
Since 2023, federal law caps the cost of each Part D-covered insulin at $35 for a one-month supply. This applies to every Medicare Part D plan, whether it’s a standalone prescription drug plan or drug coverage bundled into a Medicare Advantage plan. The cap is per insulin product, so if you use both a long-acting and a rapid-acting insulin, your maximum out-of-pocket cost is $35 for each one per month.
Two details make this cap especially valuable. First, insulin is exempt from the Part D deductible (which is $590 in 2025). You pay no more than $35 from the very first fill of the year. Second, the cap holds through every phase of Part D coverage, including the coverage gap that used to cause prices to spike. There is no point in the year where your insulin cost jumps above $35 per month.
Which Insulin Brands Are Covered
Every Part D plan maintains its own formulary, the list of drugs it covers. Plans typically include a mix of rapid-acting insulins (used around meals), long-acting insulins (used for baseline blood sugar control), intermediate-acting options, and premixed combinations. The $35 cap applies to whichever insulin products your specific plan includes on its formulary.
This means two things matter when you’re choosing or reviewing a plan: whether your particular insulin brand appears on the formulary, and whether the plan places any restrictions on it like prior authorization or step therapy. The fastest way to check is Medicare’s Plan Finder tool at medicare.gov/plan-compare, where you can enter your ZIP code and the names of your medications to compare costs across available plans. If your current insulin isn’t on your plan’s formulary, you can ask your plan for a formulary exception or switch to a covered alternative with your doctor.
Supplies Covered Under Part D
Part D doesn’t just cover the insulin itself. Federal regulations define “medical supplies associated with the injection of insulin” as a covered Part D drug category. This includes syringes, needles, alcohol swabs, gauze, and any supplies directly associated with delivering insulin into the body. Insulin pen cartridges, pen needles, and needle-free syringes also fall under Part D when they aren’t covered by Part B.
These supplies do not get the $35 cap, though. They’re subject to your plan’s normal cost-sharing rules, which means they may count toward your deductible and will have their own copay or coinsurance amounts depending on the formulary tier your plan assigns them to.
The $2,000 Annual Out-of-Pocket Limit
Starting in 2025, Part D includes a hard annual cap of $2,000 on total out-of-pocket drug spending. Once your combined costs for all covered prescriptions hit that threshold, you pay nothing for the rest of the year. Your insulin copays count toward this limit alongside costs for any other medications you take. For someone whose only significant prescription expense is insulin, the $35 monthly cap means insulin alone would not push you to the $2,000 ceiling. But if you take multiple medications, knowing that all your costs are working toward a single annual maximum can provide real financial relief.
Extra Help for Lower Incomes
If your income and resources are limited, Medicare’s Extra Help program (also called the Low-Income Subsidy) can reduce your drug costs even further. Qualifying beneficiaries pay roughly $5 for generic drugs and about $13 for brand-name drugs per prescription. Once your total drug costs reach $2,100 in a year, you pay $0 for every covered drug for the remainder of the year. People who also have full Medicaid coverage through the Qualified Medicare Beneficiary program pay no more than about $5 per covered drug at any point. Since the $35 insulin cap already applies to all Part D enrollees, Extra Help can bring insulin costs below that level for those who qualify.
How to Verify Your Coverage
Your plan’s formulary can change from year to year, so it’s worth checking each fall during open enrollment (October 15 through December 7) to make sure your insulin and supplies are still covered. You can call the number on the back of your plan membership card, visit your plan’s website, or use Medicare’s Plan Finder to search by drug name. If you’re newly enrolling, entering all of your current medications into the Plan Finder will show you estimated annual costs for each plan available in your area, making it straightforward to pick the option that covers your insulin at the lowest total cost.