Written by Hirotsugu Suwanai, MD, PhD
Journal Club of the Suwanai · Metabolism & Aging
Semaglutide is used to treat diabetes and obesity. Could its effects reach beyond blood glucose and body weight?
On September 2, 2026, Nature published a study reporting that semaglutide extended the lifespan of aged female mice. Beyond lifespan, the authors described improvements in tests of motor function and memory and in cellular markers of aging. Read the original paper ↗
Key point: did stem cells really “rejuvenate”? ↓
How did a late-life intervention change lifespan?
Treatment began in C57BL/6 female mice at 20 months of age — not as early prevention, but after the animals were already old. In the lifespan experiment, 39 control mice and 40 semaglutide-treated mice were compared, with treatment continued for life.
Median total lifespan from birth. Source: Feng et al., Nature (2026), Fig. 1a.
The difference in medians was 92 days — an extension of about 12.4% relative to controls. Note that this refers to total lifespan from birth, not a 12.4% increase in remaining life after treatment began. Methods and results
Changes in function and at the cellular level
In separate cohorts treated for three months, performance improved in tests of motor coordination, endurance, spatial memory and glucose tolerance. Markers of inflammation and cellular senescence decreased, and changes related to mitochondrial function were reported. These are individual tests and markers, however, and do not show that the whole body was uniformly “rejuvenated.”
Did stem cells “rejuvenate”? Hematopoiesis and neurogenesis
A highlight of the paper is its analysis of age-related changes in hematopoietic stem cells and neurogenesis, summarized in Fig. 2 for 20-month-old female mice treated for three months.
Hematopoietic stem cells: function beyond numbers
With age, cells classified as stem cells by surface markers increase, while regenerative capacity declines and blood production skews toward the myeloid lineage. With semaglutide, the frequency and number of LSK cells and hematopoietic stem cells decreased, while bone-marrow cellularity adjusted for body weight was maintained (Fig. 2a–d).
In colony-forming assays, colonies became fewer but larger (Fig. 2e–h), which the authors interpret as a possible improvement in per-cell regenerative capacity. The proportion of myeloid-biased stem cells and myeloid skewing in peripheral blood also decreased (Fig. 2i–l).
Hippocampus: two markers of neurogenesis increased
In the dentate gyrus, which supports memory, BrdU-positive cells (a marker of DNA synthesis and proliferation) and DCX-positive cells (immature neurons) increased, which the authors take to suggest enhanced neurogenesis. BrdU and DCX, however, do not measure the “age” of stem cells themselves.
Journal Club view: how to read “rejuvenation”
“Rejuvenation” here is best understood as improvement in age-related functional decline, lineage skewing and markers of neurogenesis, not proof that stem cells returned fully to a youthful state.
Colony-forming assays use whole bone-marrow cells and cannot by themselves establish restored long-term reconstitution or self-renewal. Whether the effects are direct on stem cells or mediated by systemic changes such as food intake or inflammation — and whether they cause the lifespan extension — are questions still to be untangled.
Can reduced food intake explain it?
A key issue is the effect of eating less: food intake fell by about 24% with semaglutide. In a separate experiment, the team directly compared semaglutide with calorie restriction matched to the same intake.
Both preserved function, but semaglutide performed better in exploratory behavior, spatial memory and aspects of glucose regulation — suggesting effects not fully explained by reduced intake. Still, this comparison does not show that semaglutide extends lifespan more than calorie restriction.
From mice to humans: open questions
Will lifespan be extended in people? This study alone cannot answer that.
Only female mice of one strain were studied. Results in males and other genetic backgrounds, and long-term efficacy and safety in humans, need testing. The extension seen in mice cannot be mapped directly onto human lifespan.
The study’s significance is in showing that late-life intervention at the GLP-1 receptor may influence multiple aging-related changes beyond metabolism. It is too early to call semaglutide a “longevity drug,” but it is a report worth following for anyone interested in the links between metabolism and aging.
REFERENCE
Feng Y, Barthez M, Wang Y, et al. Late-life semaglutide treatment slows ageing and extends lifespan in female mice. Nature. 2026;657:469–476.
doi:10.1038/s41586-026-10940-7 ↗ / Full text (PMC) ↗
This article is an independent English summary and commentary based on the original paper (© The Author(s) 2026, published under a CC BY 4.0 license). No figures are reproduced.
