What the Analysis Found
Patients using GLP-1 drugs paid less out of pocket even as the total cost of those drugs to the health system climbed steeply.
Northwestern University researchers analyzed Medical Expenditure Panel Survey data covering nearly 1,900 participants who reported using a GLP-1 medication, publishing in the Journal of the American Heart Association. Average out-of-pocket costs fell 26% among adults without diabetes and 39% among those with diabetes across the study period.
Total spending moved the other way. The gap between what patients paid and what the system paid widened, which is the finding driving the coverage.
One limitation belongs up front rather than buried. The study period ran from 2017 to 2022. It captured the 2017 approval of Ozempic for type 2 diabetes and the 2021 approval of Wegovy for weight management, but it did not include tirzepatide products such as Mounjaro and Zepbound, which arrived afterward. The data end four years ago, before the weight-loss boom that produced today's spending picture.
Why This Matters
When patients pay less and payers pay more, payers respond. That response is what a household actually experiences, and it does not arrive as a press release. It arrives as a letter saying a medication is no longer covered.
The last two years have demonstrated this concretely, and in both directions.
What Actually Happened with Zepbound
Your plan document is a moving target, and the clearest recent example runs contrary to the assumption that coverage only tightens.
CVS Caremark removed Zepbound from its standard commercial formulary effective July 1, 2025, leaving Wegovy as the preferred option. The disruption was measurable. A Truveta analysis of 700,907 patients found monthly switching away from tirzepatide rose from roughly 0.6% before May 2025 to 10.2% in the June to July period that followed.
Then it reversed. CVS Caremark announced in May that it will add Zepbound back to its commercial formularies as an additional preferred option effective October 1, 2026, and removed the new-to-market block on Foundayo, an oral GLP-1, effective June 1. The company said it worked with the manufacturer to secure a lower cost, and that eligible commercially covered patients may pay as little as $25 a month for either product.
The lesson for patients is not that coverage is getting worse. It is that coverage is volatile, and a patient stabilized on one drug can be moved off it and back again within roughly a year through no clinical decision of their own.
What This Could Mean for Household Health Decisions
The practical translation is that formulary status is worth checking annually rather than assuming continuity.
Plan sponsors that use a pharmacy benefit manager's template formulary retain discretion to customize coverage for their members, so two people with the same PBM can have different coverage. Employer plans also make separate decisions about whether to cover weight-management indications at all, and roughly one in five employer plans did as of 2025.
The Medicare picture is separate again. The Medicare GLP-1 Bridge demonstration began July 1 and may allow eligible Part D beneficiaries to pay $50 per month for certain obesity medications, but it is a time-limited pilot rather than a permanent benefit.
Who Faces the Greatest Burden
The people most exposed are those without a diabetes diagnosis, since obesity-only coverage is where restrictions concentrate and where cost-offset evidence is weakest.
Patients who have already switched drugs once face the highest risk of switching again, because they are the ones whose coverage has proven sensitive to formulary decisions. Switching between these medications is not clinically neutral, since dosing, titration schedules and side effect profiles differ.
People paying cash face a different calculation. Manufacturer direct-to-consumer programs have brought some list prices down substantially from where they started, and for someone with no coverage at all, comparing a direct-purchase price against a plan's non-covered price is worth doing rather than assuming insurance is always cheaper.
What the Evidence Shows and What It Does Not
The out-of-pocket decline is a real measurement from a nationally representative survey, but it describes 2017 to 2022 and cannot tell you what patients pay today.
It also reflects averages across a changing population. As more people gained coverage for these drugs during the study period, the mix of who was taking them shifted, and a falling average out-of-pocket cost can reflect who is using the drug as much as what any individual pays.
The study does not establish that lower patient costs caused higher system spending, or predict what payers will do next. The formulary examples above are recent history, not a forecast.
What You Can Do Now
Ask your plan three specific questions before renewal: is this drug on the formulary for the coming plan year, does it require prior authorization, and is there a duration limit. Get the answer in writing if you can.
Read plan mail about formulary changes rather than discarding it. Notice of a mid-year or annual formulary change is usually the only warning a patient gets.
If a drug is dropped, ask the prescriber about a formulary exception or appeal before switching, particularly if you are stable and doing well. Ask about manufacturer copay assistance and, if uninsured or not covered, compare the direct-to-consumer price.
Do not stop or switch a prescribed medication on your own because of a coverage letter. Titration matters, and an abrupt change should be managed by a clinician.
What Happens Next
CVS Caremark's Zepbound reinstatement takes effect October 1, which falls before most open enrollment periods close, so patients should confirm rather than assume their specific plan adopts it. CMS will assess the Medicare GLP-1 Bridge demonstration as it decides on permanent coverage. MedicalDaily will track formulary announcements ahead of the 2027 plan year.
The Bottom Line
The confirmed finding is that GLP-1 out-of-pocket costs fell 26% to 39% between 2017 and 2022 while total spending rose, and that formulary coverage since then has swung in both directions. The households most affected are those without diabetes and those already stabilized on a specific drug. The useful step is confirming formulary status and prior authorization rules before renewal. The central uncertainty is what payers do for 2027, and that will not be visible until fall.
