Can GLP-1 drugs slow biological aging?

Obesity has been linked to faster biological aging at the cellular level, not just to more years on a chart.1 A trial registered by the Second Affiliated Hospital, School of Medicine, Zhejiang University, is now directly testing whether two GLP-1-based weight-loss drugs can slow that process, measured by a specific epigenetic test rather than by weight or blood sugar alone.

What is the trial actually testing?

The official title is "Assessing the Role of GLP-1 Receptor Agonist Semaglutide and Dual GLP-1/GIP Receptor Agonist Tirzepatide in Delaying Genetic Aging in Adult Obese Patients Using the iWatchAge Technology," registered as NCT07293325.1 It is a prospective, randomized, parallel-group, open-label study - everyone involved knows which treatment each participant is receiving, which can introduce bias into self-reported or subjectively assessed outcomes, though the core measurement here is a lab test, not a questionnaire.

Researchers are enrolling 66 adults and assigning them to one of three 24-week treatment arms.1

Source: ClinicalTrials.gov record NCT07293325.1 Metformin, a decades-old diabetes drug with separately studied anti-aging signals, serves as the active comparator rather than a placebo.

How is "biological age" measured here?

The primary outcome is the change in DNA methylation-based biological age from baseline to week 24, measured using a technology called iWatchAge.1 DNA methylation clocks estimate biological age from chemical marks on DNA that shift in measurable, age-correlated patterns - distinct from chronological age, and theoretically capable of detecting whether a treatment slows or reverses that internal clock independent of how many candles are on someone's birthday cake.

The trial also tracks aging-related biomarkers, inflammatory factors, and standard metabolic parameters such as weight and glucose control, giving researchers context for whether any epigenetic-age change tracks with conventional metabolic improvement or appears to move independently of it.

"A epigenetic clock is not a crystal ball - it is a hypothesis-generating measurement, and this trial exists to test that hypothesis, not to confirm it in advance."

Who can join, and who is excluded?

Eligible participants are adults aged 18 to 75 with a BMI of 30 kg/m² or above.1 Exclusions include secondary obesity (obesity caused by another diagnosed condition), prior use of weight-loss medications without a three-month washout period, type 1 or type 2 diabetes requiring treatment, a history of pancreatitis, and pregnancy.

Excluding anyone with diabetes requiring treatment is notable: it isolates the obesity-and-aging question from the glucose-control variable, but it also means results will not directly apply to the large share of GLP-1 users who take these drugs primarily for diabetes management.

Why is this small trial worth tracking?

With only 66 participants split across three arms, roughly 22 people per group, the trial is sized to detect a large effect, not a subtle one.1 An academic sponsor with no GLP-1 drug to sell is a different funding profile than most large semaglutide and tirzepatide trials, many of which are sponsored by Novo Nordisk or Eli Lilly.2 Including metformin, a drug separately studied for its own anti-aging signal in trials like TAME, gives the comparison an active reference point rather than an untreated control.

What this does not mean - yet

NCT07293325 has produced no epigenetic-age outcome data. It cannot be cited as evidence that semaglutide or tirzepatide slow biological aging - that is the hypothesis under test, not a finding. The trial began recruiting June 2, 2025, and is listed as actively recruiting, with study completion not expected before June 2, 2027.

In one sentence: a small, academically sponsored trial in China is testing whether semaglutide or tirzepatide slow DNA-methylation-measured biological aging more than metformin, the trial has no results yet, and its small size means even a positive finding in 2027 would need confirmation in a larger study before it changes anything.