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Intervention does not impact heart disease risk

Longest-ever intervention study investigating whether weight loss reduces the risk of heart disease for patients with T2DM
Dr Rena Wing, chair of Look AHEAD and professor of psychiatry and human behaviour at the Alpert Medical School, Brown University

Weight management and increased physical activity does not impact heart disease risk, according to the results from the LOOK AHEAD (Action for Health in Diabetes) study. The results, published in the New England Journal of Medicine, randomly assigned 5145 overweight or obese patients with type 2 diabetes to participate in an intensive lifestyle intervention that promoted weight loss through decreased caloric intake and increased physical activity (intervention group) or to receive diabetes support and education (control group).  

"While the findings from the Look AHEAD study did not support that engagement in a weight- loss intervention was effective for reducing the onset of cardiovascular disease incidence or mortality, this does not mean that overweight adults with diabetes should not lose weight and become more physically active," said Dr John Jakicic, chair and professor in the Department of Health and Physical Activity in Pitt's School of Education and Director of the Physical Activity and Weight Management Research Center, principal investigator for the University of Pittsburgh's role in the study.

The primary outcome was a composite of death from cardiovascular causes, nonfatal myocardial infarction, nonfatal stroke, or hospitalsation for angina during a maximum follow-up of 13.5 years. The trial was stopped early on the basis of a futility analysis when the median follow-up was 9.6 years.


Weight loss was greater in the intervention group than in the control group throughout the study (8.6% vs. 0.7% at 1 year; 6.0% vs. 3.5% at study end). The intensive lifestyle intervention also produced greater reductions in glycated haemoglobin and greater initial improvements in fitness and all cardiovascular risk factors, except for low-density-lipoprotein cholesterol levels.

The primary outcome occurred in 403 patients in the intervention group and in 418 in the control group (1.83 and 1.92 events per 100 person-years, respectively; hazard ratio in the intervention group, 0.95; 95% confidence interval, 0.83 to 1.09; p=0.51).

“There is an overwhelming amount of evidence from this study to date that has shown that weight loss and physical activity were associated with numerous other health benefits,” he added.

The results revealed multiple other benefits for obese people with type 2 diabetes, including a reduced risk of microvascular complications and depression, an improved physical quality of life, and decreased medical costs, which were achieved by lowering the need for hospitalisation, outpatient care and medications.

"These include improving physical function and quality of life, reduction in risk factors such as lipids and blood pressure with less reliance on medication, better diabetes control with less reliance on medication, improved sleep, psychological and emotional health benefits, and many others," said Jakicic. "Thus, adults with diabetes can begin to realize many of these health benefits with even modest reductions in body weight and modest increases in physical activity."

Study participants were individuals between 45 and 75 years of age with Type 2 diabetes and a body-mass index of 25 or greater. Sixty percent of the study participants were women, while 37% were from ethnic and racial minority groups.

The Look AHEAD study was intended to run for 13.5 years, the maximum length of time researchers had determined might be required to see a difference in heart disease between two groups. After 11 years, however, the Look AHEAD Data and Safety Monitoring Board, an independent monitoring board that provides recommendations to the National Institutes of Health, reviewed the data the study had collected and determined that Look AHEAD could reach the definite conclusion that there were no differences in cardiovascular disease rates between the study's two groups.

“Look AHEAD showed that participants with diabetes can lose weight and maintain it. This weight loss has many beneficial effects on glycaemic control and CVD risk factors; however, it did not affect the risk of CVD,” said Dr Rena Wing, chair of Look AHEAD and professor of psychiatry and human behaviour at the Alpert Medical School, Brown University.

Speculating on the failure of weight loss to reduce the risk of cardiovascular disease, researchers suggested that even greater weight loss may be necessary to reduce cardiovascular risk in diabetes patients who are overweight or obese.

They also suggested that by providing participants in both groups, and their health care providers, with annual feedback on the participants' blood pressure, lipids, and blood sugar control, the cardiovascular disease risks for all experiment participants may have been reduced at a comparable rate. 

"This study shows that overweight and obese adults with type 2 diabetes can lose weight and keep it off with many important health benefits," said Dr Griffin P Rodgers, Director of the National Institute of Diabetes and Digestive and Kidney Diseases, part of the National Institutes of Health, which funded the study. "It reinforces the recommendation that overweight and obese people with type 2 diabetes should increase their physical activity levels and lose weight to improve their health."


In an accompanying editorial, Dr Hertzel C Gerstein, writes:

“The intervention strategy in this trial successfully achieved an initial between-group weight-loss difference of 7.9% at 1 year (8.6% vs. 0.7% of body weight) and reduced waist circumference, systolic blood pressure, and glycated hemoglobin levels, as compared with the control group. Nevertheless, the intervention had a neutral effect on cardiovascular outcomes, a finding that was consistent across all reported subgroups.

These considerations have several implications. It is clear that long-term outcome trials of lifestyle interventions are feasible and important to conduct. Indeed, they remain the most reliable way of determining whether any intervention has modest but clinically important effects. It is also clear that future trials will need to use different and novel strategies to maintain initially large effects on weight and other risk factors over a period of several years. Such trials should be powered to detect an effect size of 10 to 15% or choose a diabetes-related outcome that is linked to cardiovascular outcomes but that may have a quicker response to the intervention. Growing evidence suggests that the progression of diabetic retinopathy may be one such reliable outcome.

Clinicians can now use the results of the Look AHEAD study, as well as the group's previously published findings, to inform their care of patients with diabetes…with no clear evidence of cardiovascular benefit, the Look AHEAD investigators have shown that attention to activity and diet can safely reduce the burden of diabetes and have reaffirmed the importance of lifestyle approaches as one of the foundations of modern diabetes care.”

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