A semaglutide trial found 9% slower epigenetic aging, but the authors say it doesn't make anyone younger
Researchers at UC San Diego re-analysed a placebo-controlled trial and found that people on weekly semaglutide aged more slowly on DNA-methylation clocks. The sample was 108 adults with HIV-associated belly fat.
After 32 weeks, the semaglutide group showed a 9% slower pace of aging on the DunedinPACE clock and slowed PCGrimAge, which tracks mortality risk. The senior author's own caveat is explicit: 'We are not saying that semaglutide reverses aging.'
On HN, a geneticist said epigenetic clocks may simply read out things that don't affect healthspan.
What the trial measured
The work, published in *Nature Communications* and partly NIH-funded, led by first author Michael Corley at UC San Diego, re-examined a randomized trial of 108 adults with HIV-associated lipohypertrophy, a condition of excess abdominal fat. About half received weekly semaglutide for 32 weeks, the rest placebo. The team read DNA-methylation "epigenetic clocks" across several measures.
Semaglutide recipients showed slower biological aging on multiple clocks tied to inflammation and to blood, brain, heart, kidney, liver and metabolic health, including a 9% slower pace on DunedinPACE. A smaller 24-week pilot in people with HIV and fatty liver reported similar signals. The authors list the limits: unknown durability and dosing, a narrow population, and Corley's advisory role at a partner company, TruDiagnostic.
The clocks themselves are the weak link
"I am EXTREMELY skeptical of epigenetic clocks at the moment... Even though I personally expect them to be readouts of things that don't affect healthspan much, I don't have any more evidence than those trying to work out what they are." — epistasis, a commenter with a genetics-themed bio
Yet he defended running the studies, since otherwise the question stays open.
Press-release inflation
"When you see reporting like this it means there was some study that had some evidence of some effect that somewhat matches the description in the headline, but nothing more than that." — a commenter on how science headlines are made
A patient's data point
A commenter on semaglutide for several years said it tempered persistent autoimmune problems and let him come off steroids, adding that he lost 10-15 lbs but credits stopping steroids. He noted that exenatide has been around since 2005 and liraglutide since 2009, with thyroid concerns seen in rats but not people.
The tension in the thread: nobody doubts GLP-1 drugs help in conditions beyond weight loss; the open question is whether a methylation score is evidence of longer life.
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