Feb 26 (Reuters) - Medicare spending on some diabetes drugs, including popular treatments such as Ozempic, surged nearly five-fold to $35.8 billion between 2019 and 2023, a U.S. government watchdog's report showed this week.

Medicare, the government-backed program for adults aged 65 and older and those with disabilities, only covers the use of GLP-1 drugs for diabetes, but not for weight loss.

Spending on older medicines like metformin, used only for diabetes, declined. But that of popular GLP-1 drugs such as Novo Nordisk's NOVOb.CO Ozempic surged over the five years, the report by the U.S. Department of Health and Human Services' Office of the Inspector General showed.

Ozempic, which has also been used off-label for obesity, saw a more than 16-fold rise in spending to $9.2 billion in 2023 from 2019 - roughly doubling every year.

Surge in their use merits further inquiry into whether the claims were paid for appropriate use, the watchdog said.

The report comes three months after former US president Joe Biden's outgoing administration proposed expanding coverage of GLP-1 drugs to weight loss. It would be effective in 2026 if President Donald Trump's administration backs the move.

"The data brief may provide ammunition for HHS Secretary Robert Kennedy Jr. and others who see the surge in GLP-1 use as a symptom of 'overmedication' more generally in the US," said TD Cowen analyst Rick Weissenstein.

He added that the data could give Kennedy a reason to kill the proposed rule.

Kennedy has criticized drugs like Ozempic, which Novo also sells under the brand Wegovy for weight loss, saying it focused on symptoms of the obesity crisis rather than fixing the food system.

The list included popular GLP-1 drugs like Novo's Ozempic, Rybelsus and Victoza, as well as Eli Lilly's LLY.N Mounjaro and Trulicity.

The drugmakers did not immediately respond to a Reuters request for comment on the report.

(Reporting by Sriparna Roy in Bengaluru; Editing by Leroy Leo)

((Sriparna.Roy@thomsonreuters.com;))