Obese children who don't have type 2 diabetes but take the diabetes drug
metformin while improving their diet and exercise habits seem to lose a bit of
weight. But it isn't much more weight than kids who only make the lifestyle
changes, according to a new review of studies.
Some evidence suggests that metformin, in combination with lifestyle
changes, affects weight loss in obese children. But the drug isn't likely to
result in important reductions in weight, said lead researcher Marian McDonagh.
Childhood obesity is a significant health problem in the United States, with
nearly 18% of kids between 6 and 19 years old classified as obese. Metformin is
approved by the US Food and Drug Administration to treat type 2 diabetes in
adults and children over 10 years old, but doctors have used it
"off-label" to treat obese kids who don't have diabetes, according to
background information included in the study.
McDonagh's team analysed 14 clinical trials that included nearly 1000
children between 10 and 16 years old. All were overweight or obese.
Based on data in adults, weight reductions of 5% to 10% are needed to
decrease the risk of serious health problems tied to obesity, the researchers
said. The additional amount of weight loss among children taking metformin in
the review, however, was less than 5% on average.
"With childhood obesity on the rise – and [its] serious long-term
implications for the child's health as an adult – clinicians and parents are
searching for interventions that will provide meaningful weight
reduction," said McDonagh, an associate professor in the department of
medical informatics and clinical epidemiology at the Oregon Health &
"Since metformin has been used to treat type 2 diabetes for many years – including in older children – and often results in weight loss, it has been
used off-label to treat obesity in children," McDonagh said.
Weight loss as byproduct
Dr David Katz, director of the Yale University Prevention Research Center,
said metformin is effective at both treating and preventing diabetes.
The drug produces weight loss as a byproduct of treating insulin resistance,
said Katz, who was not involved with the new research.
Insulin resistance is a condition in which the body's cells become less
responsive to the hormone insulin, which helps the body control blood sugar.
Insulin resistance is a step toward type 2 diabetes.
"Obese children [in the studies] were treated without specific
consideration of their insulin status, which likely explains the lacklustre
results," Katz said. "I suspect metformin is useful in some, but not
all, varieties of obesity."
Best medicine for weight loss
In contrast, eating well and being active are effective in almost all cases
of obesity, Katz said. "It seems clear the best medicine for overweight
and obese kids is better use of their feet and forks, not something from a pill
bottle," he said.
Dr William Muinos, associate director of pediatric gastroenterology at Miami
Children's Hospital, said he prescribes metformin only for the most obese
children who are at risk for type 2 diabetes.
"In that subset of children, metformin can be very helpful in improving
insulin resistance caused by increased body fat," said Muinos, who also
runs the hospital's obesity clinic.
Metformin causes modest weight loss by lowering the amount of insulin the
body produces and improving insulin resistance, Muinos said.
The drug should not be used for weight reduction alone, he said. "It's
an adjuvant treatment, but you must start lifestyle changes," he said.
"Diet and exercise – that's the key."