Rapamycin vs Metformin
Written by Aaron CuhaReviewed Sep 2026
The short answer
The two drugs longevity clinics prescribe most, with opposite shapes of evidence. Rapamycin makes many kinds of animals live longer and has no human ageing result. Metformin has huge amounts of human safety data, a steady record of finding nothing in ageing research, and it blunts the muscle and fitness gains from training.
- Rapamycin people
- 25
- Rapamycin nulls
- 0
- Metformin people
- 489
- Metformin nulls
- 0
Dose
Approved medicine. No human dose established for unlabelled uses
Labeled amounts sit on the prescribing information. This page records what trials measured, not a personal dose.
FDA-approved (Rapamune); use for longevity is off-label (not what it is approved for) and investigational
Dose
Approved medicine. No human dose established for unlabelled uses
Labeled amounts sit on the prescribing information. This page records what trials measured, not a personal dose.
FDA approved for type 2 diabetes since 1994. Not approved for ageing or longevity.
First-hand reports are counted on each profile and never added together. This page sets two published records side by side. It does not pick a winner.
Column A
RapamycinRapamycin (Sirolimus, mTOR inhibitor)
An approved drug that blocks mTOR, a growth switch in cells. It makes many kinds of animals live longer. Some people take low, spaced-out doses for ageing, off-label. Studies in people are small.
Column B
MetforminMetformin hydrochloride (biguanide)
A cheap, very safe diabetes drug that many people take hoping to live longer. Big studies in people have not shown it helps with ageing. It also takes the edge off the muscle and fitness you gain from training.
Side by side, on the facts we can check
| What we compare | Rapamycin | Metformin |
|---|---|---|
| Category | Longevity | Longevity |
| FDA status | FDA-approved (Rapamune); use for longevity is off-label (not what it is approved for) and investigational | FDA approved for type 2 diabetes since 1994. Not approved for ageing or longevity. |
| Half-life | ~60 hours | 4 to 9 hours (plasma), longer in erythrocytes |
| Molecular weight | 914.2 Da | 129.2 Da (165.6 Da as hydrochloride) |
| How it works | It blocks the mTOR pathway. That copies part of what eating less does to cells, and it boosts cell clean-up and upkeep. | It blocks part of the energy machinery in mitochondria, called complex I, and switches on AMPK, a fuel sensor. That makes the liver release less sugar and helps the body respond to insulin. The AMPK story is not the whole answer. Research groups still argue over how much comes from complex I, from another enzyme called mitochondrial glycerophosphate dehydrogenase, and from effects in the gut. |
| Studies in people | 3 | 7 |
| Evidence | Limited: 2 completed trials, 25 people given it | Moderate: 3 completed trials, 489 people given it |
| Legal status, US | FDA-approved (for its labeled use), prescription only | Prescription only; approved for type 2 diabetes |
Frequently asked questions
What is the difference between Rapamycin and Metformin?
Rapamycin: An approved drug that blocks mTOR, a growth switch in cells. It makes many kinds of animals live longer. Some people take low, spaced-out doses for ageing, off-label. Studies in people are small. Metformin: A cheap, very safe diabetes drug that many people take hoping to live longer. Big studies in people have not shown it helps with ageing. It also takes the edge off the muscle and fitness you gain from training.
Which has stronger research evidence, Rapamycin or Metformin?
Each compound gets a band worked out from facts we counted, with the math shown. Rapamycin is Limited (2 completed trials, 25 people given it). Metformin is Moderate (3 completed trials, 489 people given it). That counts how much has been done in people. It does not rate whether either one works, and neither one is called the winner.
Are Rapamycin and Metformin FDA-approved?
Rapamycin: FDA-approved (Rapamune); use for longevity is off-label (not what it is approved for) and investigational. Metformin: FDA approved for type 2 diabetes since 1994. Not approved for ageing or longevity..
Related posts
Blog articles that cover Rapamycin or Metformin, newest first.
- Dispatch / Sep 27, 2026 / 8 minDispatch 001: Five Retatrutide Phase 3 Trials Have Finished And None Has Posted Results
- Longevity / Sep 27, 2026 / 12 minPeptides for Longevity: What the Evidence Actually Shows in 2026
- Longevity / Sep 27, 2026 / 9 minSenolytics in 2026: Dasatinib plus Quercetin, Fisetin, and What Human Trials Have Shown
- Longevity / Sep 27, 2026 / 9 minThe Rapamycin Dosing Debate: What PEARL Tested, the Bioavailability Problem, and What Is Unproven
Reviewed Sep 2026. This page puts two published records side by side. It is for learning, and it is not medical advice. When this site shows a dose, it is the dose a trial or a clinic actually used, or what people say they did, with the source attached. None of it tells you what to take.