Most of us don’t expect much from our medications beyond doing the job they’re prescribed to do — hopefully with minimal side effects. But sometimes a pill packs some welcome surprises. For example, metformin is FDA approved to treat type 2 diabetes, but people taking it sometimes notice additional advantages like weight loss and more regular menstrual cycles.
From heart health to anti-aging effects, researchers are uncovering a growing list of metformin benefits. Whether you’ve been prescribed metformin or are just curious about what it might offer, here’s a closer look at the latest science behind this old-standard drug.
What is metformin?
Metformin is an oral medication that doctors have prescribed for more than three decades as a first-line treatment for type 2 diabetes. Part of a class of drugs called biguanides, it helps control blood sugar by reducing the amount of glucose that the liver produces and that the intestines absorb from food, as well as possibly increasing insulin sensitivity.
The tablet comes in two forms: an immediate-release version that’s usually taken twice daily, and an extended-release option designed for once-a-day dosing, typically with dinner. Although metformin itself is a generic medication, it’s also found in several brand-name combinations, such as Glucophage, Riomet, Janumet, Invokamet, and Synjardy, that pair it with other active ingredients.
9 metformin benefits beyond diabetes treatment
“Metformin may also have anti-inflammatory properties, partly because of the improvement in insulin sensitivity,” says Dr. Disha Narang, M.D. endocrinologist and director of obesity medicine at Endeavor Health System in Chicago. “This can impact and potentially protect against cardiovascular disease, cancer, and cognitive changes.” Here are some of the extra benefits metformin may have beyond blood sugar control — with the reminder that many of these still need a lot more research.
Metformin and weight loss
Research has found that around 30% of people taking metformin lose more than 5% of their weight over the course of a year — and maintain that weight loss over the long term while taking it. “Unlike newer weight loss medications, metformin does not target the brain centers that regulate hunger and satiety,” says Dr. Jaime Almandoz, M.D., associate professor of internal medicine and medical director of the Weight Wellness Program at UT Southwestern Medical Center. “It works by reducing the amount of sugar produced by the liver and improving how the body responds to insulin. These changes may help decrease appetite and lead to lower calorie intake in some individuals.”
Metformin and diabetes prevention
Along with treating type 2 diabetes, metformin can also help ward it off, especially for those at highest risk for developing type 2 diabetes. In studies of the National Diabetes Prevention Program, metformin worked to keep diabetes at bay just as effectively as lifestyle modification (diet and exercise) in participants with prediabetes and a body mass index (BMI) over 35. In women with prediabetes and a history of gestational diabetes, those who took metformin reduced their risk of developing type 2 diabetes by 31% — a big impact but less than making lifestyle modifications. Still, based on research like this, the American Diabetes Association (ADA) recommends metformin for people with prediabetes to lower the likelihood of it progressing to type 2 diabetes.
Metformin and cancer
Promising early research has sparked a wave of interest in metformin’s potential anti-cancer properties. While results have been mixed, a 2024 National Cancer Institute meta-analysis of 166 studies found that taking metformin reduced the relative risk of cancer overall by up to 45%. The drug may help shut down certain proteins in the body that cause cells to grow too fast – which is one way cancer can start – as well as activate other proteins that help slow down cell growth, explains Narang. Most studies in the analysis involved people with diabetes, so more research is needed to understand whether metformin can help prevent cancer in the general population.
Metformin and fertility
Metformin has long been prescribed off-label to women with polycystic ovary syndrome (PCOS), since improving insulin sensitivity may help lower the high levels of androgen hormones and regulate the irregular menstrual cycles that are characteristic of PCOS. This, in turn, helps increase ovulation and improve fertility. Metformin can be used before or during IVF treatment to boost the chances of success in women with PCOS and may lower the risk of early miscarriage. It’s also an option for treating pregnant women with gestational diabetes. That said, the evidence for fertility-related benefits of metformin is mixed, and there may be other medications that are more effective — your provider will be able to talk with you about your options.
Metformin and aging
An anti-aging pill sounds too good to be true, but some believe metformin could be just that: Early research suggests that metformin may be able to slow down the biological clock and add years to your life, due in part to its anti-inflammatory action and possible decreased risk of cancer. “Anti-inflammatory effects are important since aging is associated with chronic low-grade inflammation,” says Naranga. Metformin may help at the cellular level, by helping cells throughout the body use energy more efficiently and repair damage more effectively. While evidence of a longevity boost is still controversial, scientists agree that metformin can improve your “healthspan” — meaning the number of years you spend feeling healthy.
Metformin and cardiovascular diseases
Studies show that people with diabetes who take metformin have a lower risk of developing heart disease and dying from cardiovascular causes than those on other diabetes medications or a placebo. “The improvement in insulin sensitivity and blood sugar control [that metformin provides] has an anti-inflammatory effect, which can help lower cholesterol and blood pressure levels and benefit blood vessels, improving heart health,” says Narang. Clinical trials are underway to determine if these metformin health benefits extend to people without diabetes.
Metformin and renal diseases
While it’s shown promise in improving renal (kidney) health in animal studies, research on humans has not yet shown a direct impact of metformin on kidneys. And in fact, severe kidney disease raises the risk of a rare but serious side effect of metformin called lactic acidosis. “If someone already has kidney disease, we would give a lower dose of metformin or avoid it altogether,” says Narang.
Metformin and liver diseases
Metformin may improve insulin resistance and liver enzyme levels in people with mild liver conditions, like early-stage MASLD (metabolic dysfunction-associated steatotic liver disease; formerly called non-alcoholic fatty liver disease), but the effects are generally modest and not necessarily associated with an improvement in health. And in people with type 2 diabetes and compensated cirrhosis (an early stage of liver scarring), studies show metformin use is linked to lower risk of death. However, if you have advanced liver disease, your liver may not clear lactic acid from your body as it should, upping the risk of lactic acidosis, a rare but life-threatening side effect of metformin.
Metformin and COVID-19
A 2023 clinical trial concluded that taking metformin after getting COVID-19 reduced the risk of developing long COVID by up to 40% in people with overweight or obesity. In 2024, researchers looked at whether the effect held true for people already taking metformin for type 2 diabetes who got COVID-19 and found that they had a 13-21% lower incidence of long COVID or death following a COVID-19 infection than people with diabetes taking different medications. Metformin may do this in two ways: by having a direct antiviral effect when taken early after a COVID diagnosis, and by calming down inflammation that can linger after the infection and contribute to long COVID symptoms.
Metformin and dementia
Metformin reduces inflammation, improves blood flow, lowers oxidative stress, and increases insulin sensitivity throughout the body — including your brain. That may be why people with type 2 diabetes who take metformin have a 24% lower risk of dementia, according to a 2025 meta-analysis.
Side effects of metformin
Metformin is fairly well-tolerated, but about 30% of people taking it experience gastrointestinal side effects, such as nausea, vomiting, diarrhea, gas, and abdominal pain. Using an extended-release version of metformin and taking the pill with meals can reduce the chance of GI upset. Other potential side effects include headache, weakness, and vitamin B12 deficiency.
Metformin is labeled with a warning for lactic acidosis, a rare but serious buildup of acid in the body. Severe kidney disease and heavy alcohol consumption increase the risk of lactic acidosis when taking metformin. For a complete list of metformin side effects, see the package insert.
The bottom line
Metformin has long been prescribed for type 2 diabetes as well as off-label for things like modest weight loss and more regular ovulation, but emerging research shows that this drug has the potential to offer an even wider range of benefits. Possible future uses of metformin include cancer prevention, reducing your risk for dementia, and preventing long COVID. While the medication isn’t prescribed for these reasons today, if you’re taking metformin already, the extra health benefits are a nice bonus.
FAQs
High blood sugar can make you feel tired or weak. Because metformin lowers your blood sugar, you may feel relief from these subtle symptoms of diabetes or prediabetes. There’s also some research suggesting that insulin resistance is associated with depression and anxiety, and that metformin may improve these symptoms.
The main sign that metformin is working is lower blood glucose readings, either in at-home blood sugar checks or in your A1C results (a routine blood test done every three months as a measure of long-term blood sugar levels in people with diabetes). You may also notice that you feel less hungry, and you may have lost several pounds over a month or two.
Though metformin lowers the amount of glucose your body absorbs from food and produces in the liver, it’s unlikely to cause hypoglycemia (low blood sugar) when taken as prescribed, even if you don’t have diabetes.
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This content is for informational purposes only and does not constitute medical advice, diagnosis or treatment. It should not be regarded as a substitute for guidance from your healthcare provider.