Metformin, a cheap and widely prescribed diabetes drug, is now at the centre of a debate that links everyday medication, ageing biology and the chance of reaching 90 and beyond. A new study in older women hints that this long‑standing treatment might do more than control blood sugar.
A diabetes prescription that might change the clock
The new analysis comes from the Women’s Health Initiative, a huge US research project that has followed hundreds of thousands of postmenopausal women for more than three decades.
For this work, researchers focused on women over 60 who had just been diagnosed with type 2 diabetes. All needed treatment. Some started on metformin. Others were given a different class of glucose‑lowering drugs known as sulfonylureas.
Those two groups were tracked for more than 15 years. During that time, the team looked at who reached very old age and who did not.
Women taking metformin had about a 30% lower risk of dying before 90 compared with those on sulfonylureas.
The findings, published in May 2025 in The Journal of Gerontology, do not prove cause and effect. They do show a strong association between metformin use and survival to advanced age in this specific group: older women with recently diagnosed type 2 diabetes.
How the study tried to mimic a clinical trial
This was not a classic randomised clinical trial, where patients are randomly assigned to treatment A or B. Instead, the team used a method called a “target trial emulation”.
In simple terms, they reconstructed, using medical records, the kind of trial they would have liked to run in real life.
- They set clear eligibility rules: women over 60, recently diagnosed with type 2 diabetes.
- They compared two starting treatments: metformin versus sulfonylureas.
- They followed outcomes over many years: did participants reach 90, or did they die earlier?
By carefully adjusting for age, weight, smoking status, blood pressure, cholesterol and other health factors, they tried to reduce bias. That long follow‑up is key. Proper randomised trials rarely last 15 years for a single drug, especially when the outcome of interest is survival to 90 or 95.
➡️ “My landlord didn’t believe it” – until I fixed mould using just salt and an old sock
➡️ Buying a military drum: best options, prices and quality
➡️ We think we are protecting our children but modern parenting rules are doing more harm than good
➡️ Remote work is silently destroying office culture and it is already too late to fix it
➡️ A basic household product washed down the pipes restored perfect flow leaving repair workers stunned
What metformin seems to do beyond lowering sugar
Metformin is usually introduced early in type 2 diabetes. It helps the body use insulin more effectively and reduces how much sugar the liver releases into the blood. Its track record on safety is strong, which is one reason doctors reach for it first.
But the new study, and a pile of previous lab work, suggest it might act more broadly on ageing processes themselves.
Metformin appears to influence several cellular pathways linked to slower ageing: oxidative stress, DNA damage, inflammation and genes tied to longevity.
Inside the cell: why ageing researchers care
In experiments on cells, worms and rodents, metformin has shown multiple effects that interest gerontologists:
- It reduces oxidative stress, the buildup of reactive molecules that damage proteins, fats and DNA.
- It activates energy‑sensing pathways in cells, which are also affected by calorie restriction.
- It appears to stimulate genes such as FOXO3, which have been linked to longevity in humans.
- It lowers chronic, low‑grade inflammation, a hallmark of ageing sometimes dubbed “inflammageing”.
In mice, early and sustained metformin treatment has extended average lifespan in some studies, delayed tumour formation and improved certain aspects of brain function. Not all experiments match perfectly, and doses used in animals do not translate directly to humans, but the pattern has been intriguing enough to earn metformin a new label in research papers: a “geroprotective” drug, meaning a drug that might protect against multiple age‑related diseases.
Beyond ageing, metformin is also being examined for potential effects on cancer risk, heart disease and dementia. Observational studies have hinted at benefits, but the picture is mixed and still under active study.
Can we call it an anti‑ageing drug yet?
The short answer from scientists is no. The new study in older women is promising, yet it remains observational. That means people were not randomly allocated to metformin or sulfonylureas. Doctors chose treatments based on their judgement, and patients lived their lives as usual.
That opens the door to hidden differences between groups. Perhaps women given metformin were slightly healthier at baseline. Perhaps they had better kidney function, or used other medicines that improved survival, or were more actively engaged with the healthcare system. Even sophisticated statistical methods cannot fully remove those uncertainties.
The study shows a strong link between metformin use and reaching 90, but it does not prove that metformin itself adds years to life.
Another point: there was no placebo group. Every woman took some sort of diabetes medication. The data might simply reflect that sulfonylureas carry more risk in very old age, for example due to episodes of low blood sugar, rather than metformin conferring extra protection.
Who was actually studied?
The participants were all postmenopausal women, most of them in the United States. That means the results do not automatically apply to men, younger adults, or people with different ethnic backgrounds or healthcare systems.
Type 2 diabetes itself varies widely in severity. Some people develop complications quickly, while others remain relatively stable for decades. The study did not fully capture those nuances, which could influence survival.
The TAME trial and the race to test ageing drugs
To move from hints to hard proof, researchers have proposed a large randomised trial called TAME, for “Targeting Aging with Metformin”. The idea is to enrol older adults who do not necessarily have diabetes, give half of them metformin and half a placebo, and then track multiple age‑related diseases.
| Question | What TAME aims to check |
|---|---|
| Does metformin delay common age‑related illnesses? | Measure time until heart disease, cancer, dementia or death occurs. |
| Is it safe in older people without diabetes? | Watch for side effects like stomach upset, B12 deficiency, lactic acidosis. |
| Can one drug affect several diseases at once? | Test the concept of targeting ageing biology, not just single diseases. |
TAME has attracted huge interest, but it also faces funding and regulatory hurdles. Ageing itself is not officially listed as a disease, which makes it harder to design and approve trials with “delaying ageing” as the main goal.
Should healthy people start taking metformin?
Right now, most experts say no. Outside of clinical trials, metformin is licensed for blood sugar control in type 2 diabetes and some related conditions, such as prediabetes or polycystic ovary syndrome. Using it purely in the hope of living longer remains speculative and off‑label.
The drug is generally well tolerated, yet it is not completely risk‑free. Common side effects include gastrointestinal upset, such as nausea, diarrhoea and abdominal discomfort, especially when treatment starts or doses increase. Longer‑term use can reduce vitamin B12 levels, which may contribute to anaemia and nerve problems if left unmonitored.
Very rarely, metformin has been linked to lactic acidosis, a serious build‑up of lactic acid in the blood. That risk rises in people with severe kidney disease or advanced heart failure, which is why prescribers check kidney function before and during treatment.
For healthy people without diabetes, the potential gains of metformin are still hypothetical, while the side effects are real.
What this could mean for women with type 2 diabetes
For women over 60 already living with type 2 diabetes, the new findings might simply reinforce current practice. Many guidelines already recommend metformin as the first‑line drug unless there is a clear reason not to use it.
In that context, this long‑term survival signal could be viewed as an extra possible advantage compared with some older drugs, especially sulfonylureas, which carry a higher risk of low blood sugar events in frail adults.
Still, personal treatment choices should reflect the whole picture: kidney health, heart conditions, other medications, and individual preferences. No single study should push someone to change their prescription without speaking to their doctor.
Ageing, metabolism and the broader conversation
The metformin story fits into a wider shift in thinking about ageing. Many scientists now see ageing not just as the passing of time, but as a set of biological processes that might be slowed or modified.
Metabolism sits at the centre of that discussion. How the body handles sugar, fat and energy shapes the risk of heart disease, stroke, dementia and some cancers. Drugs that improve metabolic health, such as metformin or newer weight‑loss injections, may reshape those risks over decades.
Imagine two women in their early 60s, both with newly diagnosed type 2 diabetes. One starts metformin, keeps active and improves her diet. The other relies on medication alone and remains sedentary. Even if metformin has some direct anti‑ageing effect, lifestyle differences will probably matter as much, or more, for who reaches 90 in good shape.
Key terms and practical takeaways
Several technical expressions around this topic can sound opaque. Two are especially useful to unpack:
- Type 2 diabetes: a long‑term condition where the body does not respond properly to insulin, leading to raised blood sugar. It is strongly linked to weight, inactivity, genetics and ageing.
- Longevity: not just living longer, but reaching older ages with less disease and better function.
For readers wondering what to do today, the most solid levers for healthy ageing remain very familiar: regular physical activity, not smoking, a balanced diet rich in plants, good sleep and control of blood pressure, cholesterol and blood sugar. If metformin eventually joins that list as a proven longevity aid, it will likely be in combination with, not instead of, those basics.
The new study in older women does not close the case on metformin as a life‑extending drug. It does, though, raise a serious question: could some of the medicines already sitting in our bathroom cabinets be quietly nudging our ageing process, for better or for worse?