Disappointing Results for Weight Loss and Diabetes

In a frustrating outcome, a long-term weight-loss program aimed at overweight adults with diabetes didn’t cut the rate of heart attacks and strokes, a major study showed.

But losing weight did provide at least one major benefit by cutting the development of chronic kidney disease, a leading cause of premature death in people with Type 2 diabetes. It also showed some ancillary benefits like cutting medicine use, depression and hospitalizations. Doctors said the finding shouldn’t discourage people—particularly those with diabetes—from exercising and eating a healthy diet. Several other studies have shown that exercise and a healthy diet can prevent people at risk for Type 2 diabetes, the most common form of the disease, from getting the disease.

New results from the study were presented Monday at the American Diabetes Association’s annual meeting and published in the New England Journal of Medicine.

Diabetes affects about 26 million Americans and is characterized by high blood-glucose levels caused by the body’s inability to either make or properly use insulin. Type 2 diabetes is associated with weight gain and older age. The disease raises the risk of heart attacks and strokes, kidney disease, blindness, amputations and nerve damage.

The study—called Look Ahead—was stopped early by the National Institutes of Health partly because it was clear a goal of showing a reduction in cardiovascular events wouldn’t be reached. The study was supposed to last for about 13 years but was stopped after patients had been followed for about a decade. Patients in the study were diagnosed with Type 2 diabetes, were overweight or obese, and were between age 45 and 75 when the study started in 2001. Although the lifestyle interventions in the study were stopped early, researchers said they continue to track the patients in the study.

Researchers wanted to know if a long-term study looking at weight loss would show a reduction in actual events like heart attacks and strokes. The study was able to successfully show that a middle-age and elderly group of patients could lose weight and keep it off for nearly a decade. Several short-term studies looking at overweight people considered to be at risk for developing diabetes and heart disease have shown benefits of losing weight, such as improved blood sugar levels, lower blood pressure and cholesterol.

The study assigned about 2,600 people to an intensive intervention group that emphasized exercise and cutting calories. About 2,600 were in a less intensive group that received counseling sessions on nutrition and physical activity. People in the intensive group initially met with a counselor weekly for the first six months of the study; those in the less intensive group started out with three counseling sessions annually. For both groups, the frequency of the counseling sessions was reduced later in the study. Patients in the more intensive group were instructed to exercise for 175 minutes a week and to consume a diet of about 1,200 to 1,800 calories a day. Those in the less intensive group—which was the study’s control group—weren’t given specific exercise or calorie targets.

During the first year of the study, patients in the intensive group lost 8.6% of their total body weight, while those in the control group lost just 0.7%. When the study stopped, people in the intensive group had lost a total of 6% of their body weight while those in control group lost 3.5%. Doctors said the 2.5% between study groups simply might not be large enough to show a reduction in cardiovascular events. Patients in the intensive group lost about 14 pounds.

Rena Wing, the study chairwoman and a professor at Alpert Medical School of Brown University in Providence, R.I., said another possibility for the study failing to meet its main goal was that patients in the control group were more likely to be on cholesterol-lowering medicines which lower the risk of heart attacks and strokes.

Exercising such as walking for just 75 minutes a week provides some health benefits, studies show, although 150 minutes is best. “It’s really better than not doing anything,” said Ronald Sigal, a professor of medicine at the University of Calgary in Alberta, Canada, during a separate presentation on exercise and diabetes. Dr. Sigal said people could consider as little as walking for 15 minutes three times a week and some sort of resistance training twice a week.

Write to Jennifer Corbett Dooren at jennifer.corbett-dooren@dowjones.com

A version of this article appeared June 24, 2013, on page D1 in the U.S. edition of The Wall Street Journal, with the headline: Disappointing Results for Weight Loss And Diabetes.