What it means
You get Part D either as a standalone drug plan added to Original Medicare or as part of a Medicare Advantage plan. Each plan has its own formulary, premium, deductible and rules such as prior authorization and quantity limits. Since 2025, Part D has had a yearly cap on out-of-pocket drug costs, adjusted each year.
By law, Part D has long excluded drugs used for weight loss alone. Plans can cover GLP-1 medicines for other approved uses, such as type 2 diabetes, lowering heart risk in adults with heart disease, or obstructive sleep apnea.
In 2025 and 2026, Medicare announced programs meant to widen coverage of weight-management medicines. Start dates, eligibility and costs have been changing, so check medicare.gov and your own plan for the current rules.
Manufacturer savings cards cannot be used with Part D.
Why it matters
Medicare coverage of GLP-1 medicines depends on the reason they are prescribed, and the rules are in flux.