An intensive diet and exercise program resulting in weight loss does not reduce cardiovascular events in people with longstanding type 2 diabetes, according to a study.

The Look AHEAD (Action for Health in Diabetes) study, supported by the National Institutes of Health, tested whether a lifestyle intervention resulting in weight loss would reduce rates of heart disease, stroke and cardiovascular-related deaths in overweight and obese people with type 2 diabetes.

Researchers at 16 centers across the United States worked with 5,145 people, with half randomly assigned to receive an intensive lifestyle intervention — including a total of 24 group and individual treatment sessions over the first six months — and the other half to a general program of diabetes support and education. Both groups received routine medical care from their own healthcare providers.

Although the intervention did not reduce cardiovascular events, Look AHEAD (www.lookaheadtrial.org) has shown other important health benefits of the lifestyle intervention, including decreasing sleep apnea, reducing the need for diabetes medications, helping to maintain physical mobility and improving quality of life.

"Look AHEAD found that people who are obese and have type 2 diabetes can lose weight and maintain their weight loss with a lifestyle intervention," Rena Wing, PhD, chairwoman of the Look AHEAD study and professor of psychiatry and human behavior at Brown University, said in a news release.

"Although the study found weight loss had many positive health benefits for people with type 2 diabetes, the weight loss did not reduce the number of cardiovascular events."

Data are being analyzed to fully understand the cardiovascular disease results. Investigators are preparing a report of the findings for a peer-reviewed publication.

Few, if any, studies of this size and duration have had comparable success in achieving and maintaining weight loss, according to the researchers. Participants in the intervention group lost an average of more than 8% of their initial body weight after a year of intervention. They maintained an average weight loss of nearly 5% at four years, an amount that experts recommend to improve health. Participants in the diabetes support and education group lost about 1% of their initial weight after one and four years.

In September, the NIH stopped the intervention arm, acting on the recommendation of the study’s data and safety monitoring board. The independent advisory board, charged with monitoring the study data and safety of participants, found that the intensive lifestyle did no harm but did not decrease occurrence of cardiovascular events, the primary study goal. At the time, participants had been in the intervention for up to 11 years.

Because there was little chance of finding a difference in cardiovascular events between the groups with further intervention, the board recommended stopping the intensive lifestyle intervention, but encouraged the study to continue following all participants to identify longer-term effects of the intervention.

"The intervention group did not have fewer cardiovascular events than the group receiving general diabetes support and education, but one positive factor we saw was that both groups had a low number of cardiovascular events compared to previous studies of people with diabetes," said Mary Evans, PhD, director of Special Projects in Nutrition, Obesity and Digestive Diseases within the NIH’s National Institutes of Diabetes and Digestive and Kidney Diseases, the study’s primary sponsor.

Participants were ages 45 to 76 when they enrolled in the study. Of the enrollees, 60% were women and about 37% were from racial and ethnic minority groups. Researchers are analyzing data to measure effects of the lifestyle intervention on subgroups, including racial and ethnic groups and people with a history of cardiovascular disease.