What Novo Nordisk and Eli Lilly reported on biological ageing
Eli Lilly and Novo Nordisk have presented research at the Aging Research & Drug Discovery conference suggesting that their weight-loss medicines may lower estimates of biological age by around two to three years. The findings concerned people with excess weight or diabetes, according to a New York Post report published on 11 October 2026.
The research involved semaglutide, sold as Ozempic and Wegovy, and tirzepatide, sold as Mounjaro. The companies used different laboratory methods to assess ageing, rather than measuring whether participants lived longer.
Novo Nordisk examined blood samples from 10,052 people, with half receiving semaglutide and half a placebo. Samples were taken at the beginning of the study and again months later, allowing researchers to examine changes in blood proteins over time.
Eli Lilly conducted a smaller study of tirzepatide using measurements based on DNA-related changes. The newspaper did not give the number of participants in that study.
The size of the apparent age reduction depended on the measurement used and the organ being assessed. One clock based on heart-related proteins suggested a difference of as much as four years. That was a result from a particular measure, not a finding that every participant’s body had become four years younger.
How biological clocks assess Ozempic and Mounjaro
Biological age is an estimate of the condition of cells and organs, distinct from the number of years someone has lived. Health conditions, smoking, diet, body weight and other aspects of life can influence the processes these estimates seek to capture.
Novo Nordisk used proteomic clocks. These analyse patterns in blood proteins to estimate age and mortality risk. Lilly used epigenetic clocks, which examine chemical markings associated with DNA rather than changes in the DNA sequence itself.
Both approaches offer ways to track molecular changes. A lower clock reading, however, is not equivalent to observing additional years of life. Nor does it establish that someone’s memory, mobility or independence has improved. Those are separate outcomes that require their own assessment.
Semaglutide mimics the action of GLP-1, a hormone involved in appetite and blood glucose regulation. Tirzepatide acts on both GLP-1 and GIP receptors. Their effects on appetite can help people eat less, while their effects on glucose regulation are important in treating type 2 diabetes.
The ageing research forms part of wider interest in the effects of GLP-1 medicines beyond weight loss. According to the Post, other studies have found improvements in blood pressure and cholesterol through a mixture of weight loss and mechanisms that do not depend on weight reduction.
That overlap leaves an important question: how much of a change in an ageing clock reflects better metabolic health, and how much represents a distinct effect on ageing? The report does not resolve this. As with research into GLP-1 medicines and inflammation, promising measurements need to be distinguished from established clinical benefits.
What ageing researchers and Lilly say about the findings
Steve Horvath, a geneticist known for developing ageing clocks, regarded the reported size of the effect as noteworthy. “Two years is a pretty strong effect, in my book,” he said, according to the Post.
Horvath interpreted the data as supporting the possibility that these medicines protect against biological ageing. That is an assessment of what the laboratory findings might mean, rather than evidence from a trial demonstrating longer survival.
Kevin Duffin, Lilly’s vice-president for ageing research, said the different clocks pointed towards a consistent reduction in estimated age. He also cautioned against expectations of a reversal amounting to decades.
The companies making the medicines presented the findings. The newspaper’s account does not supply a full trial-level assessment: it gives no exact follow-up duration, detailed uncertainty estimates or publication status for the analyses. Those omissions limit how closely readers can examine the strength and durability of the reported effects.
What the semaglutide research will test next
A separate research effort will examine outcomes that people can experience directly. The US agency ARPA-H is putting $38 million towards a study of whether semaglutide affects cognition, mobility and sensory acuity in healthy people over 60, the Post reported.
Studying healthy older adults addresses a gap in the company findings. Effects seen in people with obesity or type 2 diabetes cannot be assumed to occur in people without those conditions. The report does not give a start date or an expected date for results from the ARPA-H-funded work.
The balance of benefit and harm also remains relevant. These medicines can cause side effects and adverse events; a favourable change in a biological clock alone does not establish a reason for a healthy person to take them. For an anti-ageing claim to guide treatment, the unresolved questions concern not only molecular measurements, but meaningful benefits, their duration and the risks incurred in seeking them.
