Popular drug for Type 2 diabetes extends lifespan in mice

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A common Type 2 diabetes medication has been shown to have anti-aging and disease-preventing effects on mice.

A new study published on July 30 in Nature Communications shows that metformin may be able to increase the lifespan of mice by the equivalent of three to four human years.

Metformin is commonly prescribed to patients with Type 2 diabetes and those who are overweight, and works by helping with calorie restriction. In turn, this improves physical performance, insulin sensitivity and lipoprotein and cholesterol levels. The medication is also shown to have some anti-inflammatory and antioxidant properties.

"When two factors (lower blood sugar and lower weight) are improved upon, we know that people can live longer," Dr. Spyros Mezitis, an endocrinologist at Lenox Hill Hospital in New York who was not involved in the study, told CBSNews.com. "The same thing happens with caloric restriction, meaning when we tell people to eat less and they burn more than than they put in the system. That has been tied to a longer lifespan."

Previous studies have shown that metformin lowered the rate of tumor growth in melanoma patientsby 64 percent when combined with other treatments. A December 2012 study published in Cancer showed that ovarian cancer patients who took metforminincreased their survival rate by 20 percent compared to others who did not take the drug.

Despite the benefits, metformin does come with some side effects. Mezitis said that about 10 percent of patients experience gastrointestinal upset. It can also cause more liver and kidney problems in patients who have issues with those organs, which is why doctors shy away from prescribing the medication to patients who have pre-existing conditions.

For this study, researchers found that mice given a dose of 0.1 percent metformin had a 5.8 percent increase in lifespan and the drug significantly delayed the onset of age-associated diseases compared to mice not given metformin. The metformin mice also had better general fitness and weighed less than the control group, even though they ate more calories overall.

"It's clear that we are edging toward developing a pharmaceutical intervention that is going to be able to delay or postpone aging," study author Rafael de Cabo, a biogerontologist at the National Institute of Aging, who conducted the new mouse study, told USA Today. "For how much and how long I have no idea."

However, while there may be many positive aspects about metformin in several studies, Cabo cautioned that healthy individuals should not start taking the drug. The study showed that when mice were given more than 1 percent metformin, their lifespan decreased by 14.4 percent due to severe kidney problems compared to the control group.

Part of what makes researchers so excited about these findings is that the drug is relatively inexpensive, and there are many generic versions. Mezitis agrees that this study does bring up important points about the benefits of metformin, but more work needs to be done before we can say we have a pill that can combat disease and extend our lives.

"We should do these kind of studies in humans to prove that there is an improvement in health and an increase in lifespan in patients who use metformin," he said.

Tom Kirkwood, associate dean for aging at Newcastle University in Britain, told the BBC that while metformin has been known to help metabolism, it is unclear whether the drug has any effect on human longevity.

"We've known for a long time that modulating metabolism in mice can extend survival and postpone age-related conditions, and there are sound reasons why this should be the case is a small, short-lived animal," he said. "What we don't know however is whether similar effects on lifespan might be produced in humans. This is something that we cannot simply take for granted and the study's authors do well to sound a note of caution."

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