Biguanide medicine fact sheet
Metformin
Also known as Glucophage, metformin hydrochloride
Metformin has decades of evidence for type 2 diabetes. Observational longevity signals and small mechanistic studies do not prove that it slows aging in people without diabetes.
Quick answer
Metformin is FDA approved to improve glycemic control in type 2 diabetes, not to slow aging or extend lifespan. The anti-aging case remains a research hypothesis, and controlled studies have also found tradeoffs such as blunted muscle growth during resistance training.
By the PeptideFactSheets Editorial Team. Claims are source-checked under our editorial policy; clinician review is identified only when a named reviewer is shown.
What is Metformin?
Metformin is a biguanide medicine that lowers liver glucose production and improves aspects of glucose metabolism.
Its low cost, long clinical history, and effects on metabolic and cellular pathways made it a major drug-repurposing candidate in geroscience.
Why are people interested in it?
Observational studies in people with diabetes have associated metformin use with some favorable age-related outcomes, but treatment selection and underlying health make causal interpretation difficult.
Small trials such as MILES test biomarkers and tissue responses; they do not establish that metformin prevents aging-related disease in otherwise healthy people.
Current regulatory status
Metformin is FDA approved for glycemic control in type 2 diabetes. Aging, lifespan extension, and general healthspan enhancement are not FDA-approved indications.
What is it approved for?
- Improving glycemic control in people with type 2 diabetes as specified in FDA-approved labeling
What is it being studied for?
Evidence snapshot
There is strong evidence for diabetes treatment, but no completed large randomized trial showing that metformin extends life or delays multiple age-related diseases in people without its established metabolic indications.
Potential benefits being researched
- Metformin's glucose-lowering benefits in type 2 diabetes are established.
- Geroscience studies have measured changes in gene expression and metabolic pathways, but these surrogate findings do not prove longer or healthier life.
A mechanism, biomarker, or secondary endpoint is not proof of a meaningful clinical benefit.
Known or possible risks
- FDA labeling carries a boxed warning for rare but serious lactic acidosis, with risk shaped by kidney function and other clinical factors.
- Common adverse effects are gastrointestinal; longer use can be associated with vitamin B12 deficiency.
- A randomized trial in older adults found metformin blunted muscle hypertrophy from progressive resistance training, illustrating that pathway effects may involve tradeoffs.
What we still do not know
- Whether metformin improves lifespan or healthspan in people without diabetes
- Which age, metabolic profile, or biomarker could identify a favorable risk-benefit group
- How exercise, nutrition, and other medicines modify any geroscience effect
- Whether observational associations reflect the drug or differences between patient groups
Plain-English takeaway
Metformin is an important diabetes medicine and a serious geroscience research tool. It is not a proven longevity drug for healthy people.
Research and reference links
Use these primary and authoritative sources to verify status and read beyond this summary. A study or registry entry does not by itself prove benefit.
- 1FDA prescribing information: Glucophage and Glucophage XR
Official indication, boxed warning, contraindications, and adverse reactions.
- 2ClinicalTrials.gov: Metformin in Longevity Study
Small completed mechanistic study of tissue and metabolic responses, not a lifespan trial.
- 3MASTERS randomized exercise trial
Controlled trial reporting blunted muscle hypertrophy with metformin during resistance training in older adults.