Have you ever wondered why certain drugs are called “wonder drugs”?

Sometimes it’s because of the tremendous health benefits the drug provides for a particular condition, like insulin for type 1 diabetes or antibiotics for pneumonia. Or it may be because the drug is good for many different conditions: aspirin has often been called a wonder drug because it can relieve pain, treat or prevent cardiovascular disease and even prevent cancer.

Could metformin be on this list? It is approved in the United States for the treatment of type 2 diabetes when used with diet and exercise in people 10 years of age and older. But in recent years, interest has grown in its potential to prevent or treat a number of other conditions, including aging. Yes, aging. If true, “wonder drug” may be an understatement.

What is metformin?

The history of metformin goes back hundreds of years. In Europe, the medicinal herb Galega officinalis was popular for digestive health and for treating urinary problems and other ailments. In 1918, a scientist discovered that one of its ingredients, guanidine, could lower blood sugar. Medicines containing guanidine, such as metformin and phenformin, were developed to treat diabetes. But they fell out of favor due to serious side effects caused by phenformin and the discovery of insulin.

Metformin was rediscovered decades later and approved as a treatment for diabetes in Europe in the 1950s. It was not until 1995 that the FDA approved it for use in the United States. It has since become the most widely used medication for people with diabetes who cannot control their blood sugar through diet and exercise alone.

Metformin’s benefits may extend far beyond diabetes

For decades, we’ve known that metformin does more than just lower blood sugar in people with diabetes. It also offers them cardiovascular benefitsincluding lower death rates due to cardiovascular disease. And it sometimes helps people with diabetes lose excess weight.

Metformin may also have health benefits for people who do not have diabetes. Doctors have long prescribed it off-label — that is, to treat conditions outside of its approved use, including:

• Prediabetes. People with prediabetes have elevated blood sugar levels that are not yet high enough to qualify as diabetes. Metformin may possibly delay the onset of diabetes or even prevent it among people with prediabetes.
• Gestational diabetes. Pregnant women may develop high blood sugar that returns to normal after delivery. Metformin can help control blood sugar during pregnancy in such women.
• Polycystic ovary syndrome (PCOS). This disorder tends to affect young women whose ovaries develop multiple cysts. Menstrual irregularities and fertility problems are common. Although the results of clinical studies are mixed, metformin has been prescribed for years for women with PCOS to help with menstrual regulation, fertility and high blood sugar.
• Weight gain from antipsychotic medication. Antipsychotics are powerful medications prescribed for psychiatric illnesses such as schizophrenia. A common side effect is significant weight gain. Metformin may possibly decrease weight gain in some people who take these drugs.

In addition, researchers are investigating the potential of metformin for

Because the vast majority of research on metformin included only people with diabetes or prediabetes, it is unclear whether these potential benefits are limited to people with these conditions, or whether people without diabetes can also have benefits.

What about side effects?

The safety profile of metformin is quite good. Side effects include nausea, upset stomach, or diarrhea; these tend to be mild. More serious side effects are rare. They include severe allergic reactions and a condition called lactic acidosisa build-up of lactic acid in the bloodstream. The risk of this is higher among people with significant kidney disease, so doctors tend to avoid prescribing metformin for them.

Bottom line

Metformin is a first-line treatment for type 2 diabetes according to current diabetes guidelines. It is relatively inexpensive and its potential side effects are well understood.

If you have diabetes and need metformin to help lower your blood sugar, its other potential health benefits are a wonderful—not harmful—side effect. And if you don’t have diabetes? Well, its role in preventing or treating disease, and possibly even slowing aging and extending lifespan, is much less clear.

Although the research so far is promising, we need more convincing evidence before we approve its widespread use in people without diabetes. But for clinical researchers hoping to repurpose an old drug as a new wonder drug, metformin would seem like a good place to start.

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