Scientists from Novo Nordisk and Eli Lilly presented data at an anti-aging conference suggesting that their GLP-1 drugs slowed the molecular aging clocks of users by several years compared with placebo. Both presentations landed at the 13th annual Aging Research and Drug Discovery conference, and neither has been through peer review.

The drugs are semaglutide, sold as Ozempic and Wegovy, and tirzepatide, sold as Mounjaro and Zepbound. Tirzepatide combines GLP-1 with a second gut hormone called GIP. "Molecular clocks" here means panels of biomarkers and chemical changes that accumulate with age and can be read as an estimated biological age, separate from how many birthdays someone has had.

What the two teams measured

Novo Nordisk's scientists went back through existing clinical trial data and tracked aging-associated biomarkers in semaglutide users. Most clocks showed a slowdown of two to three years for the average user against placebo, and one clock built on heart-related proteins showed roughly four years.

Eli Lilly ran a comparable analysis on tirzepatide, looking instead at epigenetics, the chemical marks on DNA that regulate gene activity. People taking the drug appeared to age more slowly than controls on those epigenetic clocks.

"All the clocks are telling a consistent story that we're seeing a reduction in age," Kevin Duffin, vice president for aging research at Eli Lilly, said at the conference, according to MIT Technology Review. "It's not like we're going to reverse age by 30 years or something, but it's a significant reduction."

Where the evidence stops

Neither analysis has been peer reviewed, and both were run by scientists at the companies that sell the drugs rather than by independent researchers. That is two strikes before anyone argues about the biology.

The clocks themselves are the bigger open question. The field can measure age-related change, but how well an improved clock reading maps onto any tangible health outcome is not settled, and this work looked only at people with obesity or type 2 diabetes.

Bottom line

GLP-1s are already associated with reduced risk of several conditions tied to aging, including heart disease, and animal work has hinted at a longevity effect. A federally funded trial will now test directly whether GLP-1s and other drugs extend healthy aging in people over 60, which is where this question actually gets answered.