WASHINGTON, July 2 -- They knew the drugs worked. What they did not have was $1,350 a month to prove it.

On Tuesday, the Centers for Medicare & Medicaid Services officially launched its Medicare GLP-1 Bridge program, making weight-loss medications available to roughly 10 million eligible seniors at $50 a month. It is the first time in Medicare's six-decade history that the program has covered GLP-1 drugs specifically for obesity, rather than requiring a diabetes diagnosis that until now had served as the only coverage gateway.

"The sheer cost of these medications is a huge barrier to access," Dr. Mehmet Oz, the CMS administrator, said at Tuesday's launch. "That ends today."

The program covers four medications: Eli Lilly's Foundayo tabl...