On October 6, 2026, Eli Lilly and Novo Nordisk each presented new data at the Aging Research & Drug Discovery conference in Boston suggesting their GLP-1 drugs may slow measures of "biological aging," not just reduce weight and blood sugar. The findings made headlines quickly, but they come with significant caveats that are easy to miss in the coverage.

What Was Actually Presented

Novo Nordisk described an analysis of roughly 10,000 participants, split evenly between semaglutide and placebo, using a "proteomic clock" that estimates biological age from patterns of proteins circulating in blood. The company reported an overall reduction of about two to three years on this clock, with a larger effect, up to four years, specifically on proteins associated with heart tissue. Eli Lilly presented a separate analysis using an "epigenetic clock," which estimates biological age from chemical modifications to DNA, and reported a broadly similar two-to-three-year effect for tirzepatide.

Why "Aging Clocks" Are Hard to Interpret

Biological aging clocks are a genuine and active area of research, but they are not a single, standardized measurement. Different clocks (proteomic, epigenetic, and others) are built from different biological signals and don't always agree with each other on the same patient. A result that shows up strongly on one clock, such as the heart-protein signal Novo highlighted, may not show up the same way on another. That variability by clock type and by organ system is itself something researchers in the field consider when evaluating these kinds of claims, and both companies' presentations were explicit that results differed depending on which clock and which tissue was examined.

What's Missing From This Picture

Several things are worth keeping in mind before treating this as established fact. First, neither dataset has been published in a peer-reviewed journal or independently verified; this was a conference presentation of findings sponsored and generated by the drugs' own manufacturers. Second, the participants in these analyses were people being treated for obesity or type 2 diabetes, the exact populations these drugs are already approved for, so it isn't yet clear whether a similar effect would appear in healthy, normal-weight people. Third, both companies' own data acknowledged that weight loss on these drugs comes with some loss of lean muscle mass, a separate safety and functional consideration that any aging-related benefit would need to be weighed against. A federally funded study specifically designed to examine effects in healthy adults over 60, with a reported budget of about $38 million, was already slated to begin enrollment in January 2026 and should eventually provide an independent, non-industry-funded data point.

Regulatory Status

Semaglutide and tirzepatide remain FDA-approved for type 2 diabetes and, in several formulations, for chronic weight management; neither drug is FDA-approved for an anti-aging or longevity indication, and this presentation does not change that status. Any discussion of "slowing aging" at this point describes an exploratory research finding, not an approved use of either medication.

The Bottom Line

This is a real, dated development worth tracking, two major manufacturers independently reporting a consistent direction of effect using two different aging-clock methods. But it is early-stage, company-generated, unpublished data in people already being treated for metabolic disease, not a demonstrated anti-aging benefit in the general population. Anyone curious about what this might mean for their own treatment should raise it with their prescribing physician rather than treating a conference presentation as clinical guidance.