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SUNDAY, March 14 (HealthDay News) -- Hopes that two available drugs could help prevent diabetes and the problems it causes in overweight people with poor sugar metabolism have been dashed by a major international study.
The trial involved two drugs prescribed for other reasons -- Diovan (valsartan), a blood pressure medication; and Starlix (nateglinide), which is given to control existing type 2 diabetes.
The study was financed by Novartis, the drug company that markets both products.
The Starlix portion of the five-year trial, involving more than 9,300 overweight adults, found the drug had no benefit in reducing the incidence of newly diagnosed diabetes, cardiovascular death or events such as heart attack, stroke and heart failure.
The Diovan portion did find a modest effect -- 14 percent -- in preventing new diabetes cases. However, as was the case in the Starlix part of the trial, using Diovan led to no reduction in the cardiovascular conditions for which diabetes is a major risk factor.
Results of the trial were reported in two papers released early on March 13 by the New England Journal of Medicine, and slated for presentation Sunday at the American College of Cardiology's annual meeting, in Atlanta.
"It would be great if we had something that would prevent diabetes and cardiovascular disease at the same time," said Dr. Robert M. Califf, vice chancellor for clinical research at Duke University, and one of the leaders of the trial. "We didn't get that."
And despite the faintly positive results of the Diovan portion of the trial, "in neither case would we recommend such prophylactive [preventive] treatment in people who don't have diabetes but have abnormal glucose tolerance," Califf said.
So, lifestyle remains the key factor in preventing obesity and poor blood sugar control from turning into full-blown type 2 diabetes, he said.
"It looks like diet and exercise are the mainstays of prevention," he said. "If people could lose a few pounds more and exercise more, there would be a lot less diabetes."
It's an old message, but one that is difficult to get across, said Califf, who noted that more than 35 percent of the people in the trial did go on to develop diabetes in just five years. "We need to keep looking for better treatments, but lifestyle modification is the best thing we have going," he said.
The people in the trial, which was done at 806 centers across 40 countries, had diagnosed cardiovascular disease, known risk factors such as obesity and impaired ability to metabolize sugar.
They were divided into groups -- some receiving Diovan, some getting Starlix, and some taking a placebo. All entered a lifestyle modification program aimed at reducing weight and dietary fat intake and increasing physical activity.
Over five years, 36 percent of those taking Starlix developed diabetes, compared to 34 percent of those taking a placebo. Diabetes developed in about a third of those taking Diovan, compared to about 37 percent of those taking a placebo. The rates of cardiovascular problems and deaths were similar in all groups.
"We must continue to develop new therapies while encouraging people to exercise and pay attention to what they eat," Dr. John McMurray, professor of cardiology at the University of Glasgow in Scotland and a member of the trial's executive board, said in a Duke University news release. "Losing at little as 5 percent of body weight has been shown to make a dramatic difference in other studies."
Diabetes is a growing world-wide medical problem, McMurray and Califf noted. Some 150 million people now have the disease -- 90 percent have type 2 diabetes -- and the incidence is predicted to increase 50 percent by 2025.
There is an inexpensive drug available that has been shown to help prevent diabetes, added Dr. David M. Nathan, a professor of medicine at Harvard University and director of the Diabetes Research Center at Massachusetts General Hospital, who wrote an accompanying editorial in the New England Journal of Medicine. It is metformin, a leading drug for diabetes treatment that has been used for decades.
A study he led reported in 2002 that metformin reduced new diagnoses of diabetes by 58 percent over three years and by 34 percent over 10 years, Nathan wrote. But lifestyle changes, such as eating less and exercising more, are equally effective preventive measures, he said.
Find out how you can help prevent diabetes at the American Diabetes Association.