Preventing Metabolic Syndrome with Diet, Exercise, and Medicine

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Orchard TJ, Temprosa M, Goldberg R, et al.: The effect of metformin and intensive lifestyle intervention on the metabolic syndrome: The Diabetes Prevention Program randomization trial. Ann Intern Med 142:611-619, 2005.

What is the problem and what is known about it so far?

Millions of Americans have metabolic syndrome (a group of signs and symptoms including high blood pressure, large waist size, poor blood glucose control, and high levels of fat in the blood). But little is known about how to prevent metabolic syndrome in people with poor glucose tolerance, a condition where the body does not use glucose properly. Metabolic syndrome raises our chances of getting cardiovascular disease (disease of the heart and blood vessels), other disabilities, and dying.

Why did the researchers do this particular study?

They wanted to find out how common metabolic syndrome is among people in a diabetes prevention study, and to see whether diabetes medication or lifestyle changes (like a healthy diet and exercise) lower a person's chances of getting metabolic syndrome.

Who was studied?

The study included 3,234 people in the Diabetes Prevention Program, all of whom had poor glucose tolerance.

How was the study done?

Each participant had a physical examination and blood drawn for laboratory tests.

Participants were given 850 mg of metformin (a drug that stimulates the body to make more insulin) twice a day, or a placebo (a "sugar pill" that has no effect), or were given intensive lifestyle training. The lifestyle training was designed to reduce weight by at least seven percent, by following a low-calorie, low-fat diet with at least 150 minutes of physical activity per week.

Participants were followed for three years, with a physical exam and blood tests repeated yearly.

What did the researchers find?

More than half of the participants had metabolic syndrome at the study's beginning. Forty-one percent of those who made lifestyle changes no longer had metabolic syndrome at study's end. In addition, 17% of the participants who took metformin no longer had metabolic syndrome at study's end.

What were the limitations of the study?

The study included people with poor glucose tolerance but not diabetes, so the results may not apply to other groups of people.

Researchers did not get detailed information about what participants ate, which could have an impact on health.

What are the implications of the study?

Therapies intended to treat glucose intolerance also help prevent metabolic syndrome. In addition to improving glucose control, people who make lifestyle changes and take metformin may reduce their chances of developing disease of the heart and blood vessels.