In January, Jeff La Marca received a prescription for Zepbound, the popular weight-loss drug. But the $750 monthly price tag was out of reach.

When Medicare later launched an 18-month pilot program offering GLP-1 medications to some enrollees for $50 a month, La Marca believed he might finally be able to afford treatment.

“I thought, ‘Thank God, there’s a path,’” said La Marca, who lives in Basking Ridge, New Jersey, and has tried numerous diets and exercise regimes.

But the 68-year-old’s relief was brief.

His application to the pilot program was denied.

La Marca has severe obstructive sleep apnea, one of several diagnoses that exclude patients from the Bridge program’s $50 monthly price. The denial notice did not explain why he was rejected. La Marca believes that without that diagnosis, he would qualify based on his weight.

“I’m obese, morbidly obese, BMI 42. I had quadruple heart bypass surgery. I’m at risk for stroke. I’m prediabetic. And yet I can’t get it. I’m livid,” he said.

A temporary fix for a long-standing gap

About 1 in 5 American adults have taken a GLP-1 medication, and most of them — including people with health insurance — say the drugs are difficult to afford. Federal law has long barred Medicare from covering drugs prescribed solely for weight loss, which helped make the Medicare GLP-1 Bridge program a major development when it launched in July.

The short-term pilot program gives Medicare coverage for three GLP-1 drugs for weight loss and weight management, in an effort to determine whether the coverage could save Medicare money over time. To qualify, patients must be enrolled in Medicare Part D, the prescription drug benefit attached to Medicare. Although Part D enrollment is required, the prior authorization request does not go through the insurer. Instead, it is submitted through a separate system run by a contractor for the Centers for Medicare & Medicaid Services.

The pilot covers Wegovy, the KwikPen formulation of Zepbound, and the oral medication Foundayo.

Under the program, many Medicare beneficiaries with a body mass index of 35 or higher — the upper end of obesity — qualify for coverage of one of the drugs if prescribed. People with a BMI between 27 and 34 may also qualify if they have certain conditions, including prediabetes or cardiovascular disease.

But a key distinction buried in the fine print is causing problems for patients like La Marca: the $50 price under Bridge applies only to people taking the drug solely for weight loss. Anyone with a qualifying medical condition that the Food and Drug Administration has approved GLP-1s to treat, including Type 2 diabetes or moderate to severe obstructive sleep apnea, is instead routed back to their Medicare Part D prescription drug plan, which can require copays of hundreds of dollars a month for GLP-1s.

“The Bridge program was designed to target those people who can’t get GLP-1 coverage through Part D but would benefit from taking one for weight loss,” said Juliette Cubanski, who directs the Program on Medicare Policy at KFF, a health information nonprofit that includes KFF Health News.

How much the program will cost Medicare depends largely on how many people use it, and the federal government has not released an estimate.

Cubanski has estimated that 3.8 million people meet the criteria and that if a quarter of them enroll in Bridge and stay on treatment for the program’s full 18 months, Medicare would spend about $3.3 billion. If three-quarters enroll, the cost could rise to $10 billion.

If the government expanded the program to include the additional 5.9 million people who are overweight and already eligible for GLP-1 coverage through Medicare Part D, the cost would increase by billions more.

CMS spokesperson Timothy Foster said the first weeks of the demonstration have been positive and that most prior authorization requests have been completed in under 12 hours.

“This has allowed thousands of eligible beneficiaries to access GLP-1 medications for weight loss at pharmacies nationwide,” Foster said.

GLP-1s aren’t covered

For patients like La Marca, the result is a difficult contradiction: they may qualify for Part D coverage of a GLP-1, but the drug still comes with much higher cost sharing.

“‘Coverage’ doesn’t always mean ‘affordable,’” said primary care physician Taylor Lacy, who describes herself as a “big proponent” of GLP-1s and practices at Sunflower Medical Group in Roeland Park, Kansas.

Lacy said the Bridge program is leaving behind patients with the greatest medical need. She noted that many Medicare patients must already navigate prior authorization and spend months trying alternate, often cheaper treatments — a process known as step therapy — before finally receiving approval, only to discover at the pharmacy counter that their GLP-1 copays will be $200 to $600 a month, or more.

Researchers studying how Medicare insurers cover GLP-1s have found that recipients have faced higher out-of-pocket costs and that nearly all plans now require prior authorization, making access more difficult.

Chris Bond, a spokesperson for the insurance industry trade group AHIP, blamed drugmakers’ prices, “which they alone set and they alone can lower.”

La Marca’s insurer declined to answer specific questions about his case.

Left waiting

For now, La Marca’s GLP-1 prescription remains unfilled. The severe sleep apnea diagnosis that helps establish his medical need is also what excludes him from the discount program that would put the drug within reach.

Reflecting on his appeals and repeated dead ends, La Marca paused, his eyes filling with tears of frustration.

“This is now my quest, because it’s my only chance to improve my health,” he said. “It’s the only thing left. I’ve tried everything.”

KFF Health News is a national newsroom that produces in-depth journalism about health issues and is one of the core operating programs at KFF, an independent source of health policy research, polling, and journalism.

This article first appeared on KFF Health News and is republished here under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. This story was originally featured on Fortune.com