TUESDAY, July 30 (HealthDay News) -- A new study in mice hints
that the widely used diabetes drug metformin might have
life-extending benefits beyond its effects on diabetes.
The study found that a small dose of metformin, given regularly
in middle age, boosted the health of mice and extended their lives,
while a larger dose shortened their lives.
"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," study leader Rafael de Cabo, of the U.S.
National Institute on Aging (NIA), explained in a U.S. National
Institutes of Health news release.
The drug was given to the mice beginning in middle age and two
doses of metformin -- 0.1 percent and 1 percent -- were tested by
the international team of scientists. The mice that received the
0.1 percent dose lived nearly 6 percent longer than mice in a group
that received no metformin, the researchers said.
But the mice that received the larger dose of metformin had
their lifespans shortened by an average of more than 14 percent
compared to mice not on the drug, likely due to kidney failure.
On the other hand, the lower dose of metformin did not appear to
have any effect on the kidneys, according to the study published in
the July 30 issue of the journal
According to the study, metformin appears to boost the use of
fat for energy in mice and it also helped them maintain body weight
as they aged, a characteristic that other studies have found is
associated with longer survival.
The mice that received metformin also had lower rates of
cataracts, a common health problem in the strain of mice used in
the study. Metformin also prevented the onset of metabolic syndrome
-- a group of symptoms that increase the risk for type 2 diabetes
and heart disease -- and appeared to have some antioxidant effects
in the rodents.
Metformin, which has been used for decades to treat type 2
diabetes, improves insulin sensitivity, spurs sugar to be converted
to energy and prevents sugar buildup in the liver. It also reduces
risk of health issues associated with metabolic syndrome.
One expert said the study does seem promising.
"This study is highly credible and suggests that metformin may
be useful to treat a range of age-related diseases, possibly
including cancer in humans," said Charles Mobbs, a professor of
neuroscience, endocrinology and geriatrics at the Icahn School of
Medicine at Mount Sinai in New York City.
"It should be noted that mice do not develop diabetes with age
(their blood glucose actually tends to fall with age) so the
protective effects of metformin to increase lifespan is probably
not due to its anti-diabetic effects, per se," he added.
According to the study's authors, the new findings suggest that
metformin may mimic some of the health benefits of calorie
restriction -- limiting the amount of calories taken in each day
from food -- that have been seen in some studies with animals.
While the findings of the new study are promising, scientists
note that research involving animals often fails to produce similar
results in humans.
"The mechanism of action of metformin, by increasing insulin
sensitivity and reducing inflammation, corroborate its
health-improving effects," said Dr. Spyros Mezitis, an
endocrinologist at Lenox Hill Hospital in New York City.
However, Mezitis, who was not involved in the new research,
cautioned that "studies in humans should confirm the health
improvement data in mice."
Still, Mobbs remained optimistic.
"Metformin is widely prescribed to diabetic patients, and
produces among the lowest mortality rate in these patients compared
to other drugs used to treat diabetes," Mobbs said. "Several
studies have demonstrated the drug extends lifespan and reduces
tumor burden in other animal models, so the present results are
He added that "obviously, metformin should only be used under
the care of a physician. At present the drug is only approved for
use to treat diabetes, though this may change."
The American Academy of Family Physicians outlines
good health habits at age 60 and beyond.