Metformin is a drug commonly used to treat type 2 diabetes. But new research published in the Proceedings of the National Academy of Sciences (PNAS) finds the medication may also slow the aging process and increase lifespan.

Metformin belongs to a class of drugs known as biguanides. For patients with type 2 diabetes, it helps control blood sugar by reducing the amount of glucose absorbed from food and the levels of glucose produced by the liver. It also increases the body's natural response to insulin.

But studies have suggested that the health benefits of metformin may reach further than type 2 diabetes. In 2010, Medical News Today reported on two studies that suggested metformin may protect against lung cancer in smokers. A 2012 study also found that the drug may show promise in treating patients with pancreatic cancer.

Now, a research team led by Wouter De Haes of the Katholieke Universiteit Leuven (KU Leuven) in Belgium finds that metformin may be useful for halting the aging process.

Testing metformin in roundworms

To reach their findings, the team conducted a series of experiments in the roundworm Caenorhabditis elegans - a model they say is ideal for studying the aging process as it only has a 3-week lifespan.

The team found that metformin increased the number of toxic molecules released in the worms' cells, which they were surprised to find boosted their long-term strength and longevity.

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On testing metformin in the roundworm C. elegans, the researchers found the worms showed no wrinkling, aged slower and stayed healthier for longer.
Image credit: Wouter De Haes

"As they age, the worms get smaller, wrinkle up and become less mobile. But worms treated with metformin show very limited size loss and no wrinkling. They not only age slower, but they also stay healthier longer," says Haes.

But how does metformin work? The team explains that our body's cells get their energy from mitochondria - the "powerhouses" in each cell that trigger small electric currents. This process can generate highly reactive oxygen molecules.

These molecules can be harmful to the body. They can damage proteins and DNA and interfere with normal cell functioning. But the team says the molecules can also be beneficial in small amounts.

"As long as the amount of harmful oxygen molecules released in the cell remains small, it has a positive long-term effect on the cell. Cells use the reactive oxygen particles to their advantage before they can do any damage," explains Haes.

"Metformin causes a slight increase in the number of harmful oxygen molecules. We found that this makes cells stronger and extends their healthy lifespan."

Antioxidants 'may stop metformin from working'

The investigators say previous research has indicated that harmful reactive oxygen molecules are to blame for the aging process. Furthermore, it is believed that antioxidants may help prevent these molecules from causing damage.

However, the researchers note that antioxidants may counteract metformin's anti-aging effects, as they found that the harmful molecules need to be present in cells for the drug to work.

Although these findings in roundworms are promising as an effective anti-aging strategy, Haes notes that further research is needed:

"While we should be careful not to over-extrapolate our findings to humans, the study is promising as a foundation for future research."

This is not the only study to flag the anti-aging potential of metformin. Last year, Medical News Today reported on a study by researchers from the National Institutes of Aging (NIA), which found that mice who received metformin had a 5.83% increase in lifespan, compared with control mice.

Commenting on the findings of that study, Richard Hodes, director of the NIA, said:

"There is increasing interest in exploring how drugs for one use might be repurposed for another. It is exciting to discover that a drug already known to be safe and effective in humans might be further studied for a possible, alternate use for healthy aging."