Millions of older Americans will soon have Medicare access to GLP-1s for weight loss. Here’s what they need to know.

Starting July 1, Medicare Part D will begin covering GLP-1 drugs prescribed for obesity — a historic policy reversal that had previously excluded weight-loss medications from Medicare coverage. Millions of eligible Americans aged 65+ now stand to gain access to drugs like semaglutide (Wegovy) and tirzepatide (Zepbound), which have already transformed the commercial market for obesity treatment.

The two dominant names are Novo Nordisk (NVO) and Eli Lilly (LLY), the makers of Wegovy and Zepbound respectively. Both have been in a fierce race to scale manufacturing, lock in formulary placement, and defend pricing — all of which will now face a new test in the price-sensitive Medicare channel, where rebate negotiations tend to compress net realized prices significantly.

The bull case is straightforward: this dramatically expands the total addressable market overnight. Medicare enrollment is large and the obesity prevalence among older adults is high. Any meaningful uptake translates into incremental script volume for LLY and NVO at a time when both companies are still ramping capacity.

The bear case, however, is real. Medicare's negotiating leverage — especially under the Inflation Reduction Act framework — could drive net prices materially lower than the commercial list price. Formulary restrictions and prior authorization hurdles may also throttle actual utilization well below the theoretical ceiling.

The key near-term watch items are formulary inclusion decisions by major Part D plans ahead of July 1, any CMS guidance on coverage criteria and prior auth requirements, and quarterly earnings commentary from LLY and NVO on Medicare channel pricing and volume expectations.