Diabetes Treatment Expands Lifespan in Male Mice

Mice given an anti-diabetes drug have been shown to live longer, new research form the US National Institute on Aging (NIA) suggests.

Middle-aged male mice that were given a low dose of the type-2 diabetes drug metformin had improved health and saw a six percent increase in lifespan compared to a control group.

Higher doses of metformin were found to be toxic to the mice.

Human implications of the research are unclear, though scientists say metformin may mimic the effects of extreme calorie restriction, an effect which may show promise in expanding human longevity.

"Aging is a driving force behind metabolic syndrome and diabetes. Given that metformin is clinically proven to alleviate symptoms of these conditions, and reduce risk of cancer, we thought perhaps it was a good candidate to study for its broader effects on health and lifespan," said Rafael de Cabo of the NIA's Intramural Research Program.

Metformin, which has been prescribed as a type-2 diabetes treatment since the 1960s, is known to enhance insulin sensitivity, prompt sugar to be converted to energy, and prevent sugar build up in the liver, the NIA reports.

The drugs also reduces risk of health issues associated with metabolic syndrome, a condition characterized by an increased chance for heart disease and stroke, as well as type-2 diabetes.

"There is increasing interest in exploring how drugs for one use might be repurposed for another," notes Richard J. Hodes, M.D., director of the NIA. "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."

For the study, groups of mice were given a treatment containing 0.1 percent metformin or 1 percent metformin and monitored. A control group of mice given no metformin was also studied.

The mice given the smaller dose of metformin had a 5.83 percent increase in lifespan. But mice given the higher 1 percent dose showed a 14.4 percent shorter lifespan compared to the control group.

Researchers state there was a "clear health benefit" to mice given the 0.1 percent metformin treatment.

"These mice had improved general fitness and weighed less than the control group mice, despite consuming more calories," the NIA states. Metformin increased the mice's use of fat for energy and the mice on metformin tended to preserve body weight with age, a characteristic associated with increased survival in other studies.

"These are very promising results that need to be translated to humans via clinical studies," de Cabo told the BBC.

Whether the same effects will be shown in humans, however, remains unknown.

"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," Tom Kirkwood, associate dean for ageing at Newcastle University, told the BBC.

"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."