Diet Drug May Help Prevent Diabetes

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May 10, 2000 -- Not only can the diet drug Xenical help overweight people drop weight and keep it off, the weight loss can leave them less likely to develop diabetes -- even if they shed only a few pounds, an international team of researchers has found.

Researcher Steven B. Heymsfield, MD, tells WebMD that the study, published in Archives of Internal Medicine, will help sweep away the misconception that overweight people need to lose a great deal of weight to gain health benefits.

Participants in the research started out at an average of 220 pounds, Heymsfield, of the College of Physicians and Surgeons at Columbia University in New York, tells WebMD. "At best, they lost about 10% of their body weight, which puts them at about [200 pounds]. By any measure that is [still] overweight," he says. Yet the study showed that their ability to handle glucose was significantly improved.

Obesity is a major risk factor for type 2 diabetes, which results from the body's inability to respond to insulin and leads to a higher than normal level of sugar, or glucose, in the bloodstream.

To test their theory that losing a small amount of weight would improve glucose regulation, Heymsfield and colleagues from the U.S., Finland, England, and Sweden looked at the results of three clinical trials of Xenical involving 675 obese men and women. The drug, which is approved by the FDA for treating obesity, works by blocking the enzyme that breaks down fat, meaning less dietary fat is absorbed by the body.

The men and women who took Xenical three times a day and followed a moderately low-calorie diet lost an average of almost 15 pounds. Others, who took a placebo and followed the same diet, lost an average of about eight pounds. At the end of the second year, the Xenical group had maintained a weight loss that was about six pounds greater than the placebo group.

At the beginning of the study, the men and women had a blood test to detect how well their bodies used glucose. The test was repeated at the end of the study.

The researchers found that the dieters who had impaired glucose tolerance before taking Xenical progressed to type 2 diabetes more slowly than those who took the placebo. They also found that modest weight loss brought about improved blood glucose levels in those who didn't yet have diabetes, but who had impaired glucose tolerance when the study began.

"They have proven ... what we have suspected -- that weight loss can prevent or treat diabetes," says Ian Yip, MD, who reviewed the study for WebMD. "Ninety percent of type 2 diabetics have what obesity experts call 'diabesity.'" Yip is associate chief of the division of clinical nutrition at the University of California at Los Angeles School of Medicine.

The study confirms that glucose tolerance is improved in people who lose weight, Christopher D. Saudek, MD, vice president of the American Diabetic Association, tells WebMD. But the study participants taking Xenical probably knew they were on the real drug, Saudek says, because of common side effects: gas, a frequent urge to have a bowel movement, and oily stools.

"One of the ways the medication acts is to warn people off fat," says Saudek, who was not involved in the study. "When you eat fat, you get the side effects ... that's a motivator to stay off fat."

The study is a very important step, Leslie J. Domalik, MD, tells WebMD. He says its findings will steer doctors and overweight people away from the belief that one must reach an "ideal weight" to reap health benefits. Domalik, an assistant professor of medicine in the division of endocrinology at Duke University Medical School in Durham, N.C., was not involved with the study.

"If you look at the difference between the [Xenical] and the placebo groups, there was only about a six pound difference" at the end of the second year, Domalik says. "Yet that difference really equated with better glucose tolerance."

The study was supported by a grant from Hoffmann-La Roche Inc., which manufactures Xenical.

Vital Information:

  • New research shows that that weight-loss drug Xenical helped patients lose weight and keep it off.
  • Even though the amount of weight loss was small, patients who lost weight were better able to control their glucose, preventing or slowing the development of diabetes.
  • Researchers say the findings are important because they show that losing even a small amount of weight can have health benefits.
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