Semaglutide and lifespan: what the mouse study found

Semaglutide, the medicine in Wegovy, made old female mice live longer in a study the journal Nature published on September 2, 2026 [9]. It is a mouse study. It does not show that the drug slows aging or adds years in people, and the authors themselves say long-term studies in older adults would be needed to find that out [8].

What the researchers did

The team worked in a University of California, Berkeley nutrition and metabolism department [12]. They gave female mice that were already 20 months old a daily semaglutide injection under the skin [3]. One group stayed on the drug for the rest of their lives, which is where the lifespan result comes from. A separate group was treated for 3 months so the team could measure movement, memory, muscle and cell-level signs of aging [3]. In that shorter test the drug improved physical function and reduced several markers the researchers use to track aging [1].

The lifespan number

Median lifespan was 742 days in the untreated mice and 834 days in the treated mice, a gap of 92 days [2]. Median means half the animals in each group had died by that age.

Was it just eating less?

That is the obvious question. The drug cut how much the mice ate by 24% [4], and eating less without malnutrition is itself known to slow aging and extend life in many species [11]. So the team ran a second experiment: for 5 months they compared semaglutide with a diet cut by the same 24% [5].

Most measures moved the same way in both groups. On three of them the drug group did better than the diet group: time spent exploring the open center of a test arena, a maze test of spatial memory, and glucose tolerance [6]. The authors read that as a sign the drug does more than reduce calories. That is their interpretation of mouse data, not a finding in people.

Why this does not carry over to people yet

• Only female mice were tested. The authors say they picked females to avoid the fighting and injuries seen in male mice kept together for long studies [7].
• The mice got an injection every day [3]. Wegovy for people is a once-weekly shot [13], and the study did not test any human dose or schedule.
• The authors write that long-term clinical studies in older people would be needed to know whether the drug changes aging or lifespan in humans [8].
• The paper’s competing-interests note says the University of California has filed a patent application on GLP-1 drugs for healthy aging [10].

Wegovy’s FDA label lists what it is approved to do, including long-term weight reduction in adults with obesity or overweight with a related condition [14] and lowering the risk of heart attack, stroke and cardiovascular death in adults with heart disease and obesity or overweight [15]. Slowing aging is not on the list. For all five brand-name GLP-1s, see what each GLP-1 is approved for.

What to do with this news

Nothing about your own treatment changes because of a mouse study. If you already take a GLP-1, do not change the dose or add a second product on the strength of this paper; ask the prescriber who manages it. Be careful with any seller that uses this study to market a GLP-1 product. The FDA warns that unapproved versions of semaglutide skip its review of safety, effectiveness and quality [16]. Our guide to fake and unapproved GLP-1 products lists the warning signs.