Medicare beneficiaries face higher costs, near-universal prior authorization for GLP-1 drugs

Medicare Part D coverage of glucagon-like peptide-1 receptor agonists (GLP-1RAs) — widely prescribed for diabetes and increasingly sought for obesity and related conditions — has remained broad. As of 2025, most beneficiaries still had access to the drugs, with coverage rates of 85% or higher for oral semaglutide (84.8%), dulaglutide (87.5%), tirzepatide (96.2%) and injectable semaglutide for diabetes (98.0%).

A research letter published Sept. 24 in JAMA, found that insurers have sharply increased restrictions.

Nearly all GLP-1 prescriptions now require prior authorization — up from 2.8% to 5% in 2020-2023 to nearly 100% in 2025.

Coverage for non-diabetes indications remains minimal. No beneficiaries had coverage for tirzepatide prescribed for obstructive sleep apnea, and just 1% had coverage for semaglutide for cardiovascular disease.

Patient costs climb under new rules

The study also highlights rising patient costs. Average monthly out-of-pocket (OOP) expenses for established GLP-1 drugs increased from $75-$138 in 2024 to $122-$167.

Standalone Part D plans accounted for the steepest increases. Between 2024 and 2025, monthly costs in these plans jumped from $99-$109 to $175-$196. By contrast, Medicare Advantage Part D plans saw smaller increases, from $52-$64 to $93-$101.

The spike coincides with a shift from flat copayments to percentage-based coinsurance. In 2025, 49% to 77% of beneficiaries faced coinsurance requirements, up from 27% to 36% in 2024.

Policy shifts

Researchers noted that the Inflation Reduction Act (IRA), which introduced a $2,000 annual OOP cap starting in 2025, may be partly responsible for the changes. Because the IRA increased plans' financial responsibility for catastrophic drug costs, insurers may be offsetting that liability by tightening prior authorization rules and raising patient cost-sharing.

"From 2020 to 2025, prior authorization for GLP-1RAs became near universal and OOP costs rose substantially in 2025, as plans increasingly required coinsurance," the authors wrote. They added that, while Medicare Advantage plans can buffer costs through rebates and incentives tied to medication adherence, standalone Part D plans have fewer options.

The authors cautioned that the study did not account for deductibles or the new $2,000 OOP maximum. Even so, the findings suggest that beneficiaries face growing barriers to accessing GLP-1 therapies, despite widespread formulary inclusion.

Looking ahead

With GLP-1s now among the highest-cost drugs in Medicare, coverage decisions are likely to remain under scrutiny. The authors concluded that, "given the budgetary impact of GLP-1Ras for Medicare, ensuring beneficiary access and affordability will remain challenging."