Intentional weight loss does not reduce cardiovascular events in overweight or obese patients with type 2 diabetes, according to a recent study published in The New England Journal of Medicine.
“Our study showed than an intensive lifestyle intervention did not reduce the risk of cardiovascular morbidity or mortality…among overweight or obese patients with type 2 diabetes,” reported Rena R. Wing, PhD, of the Weight Control and Diabetes Research Center, and colleagues.
Weight loss has been shown to be effective—and is recommended—in the short term for overweight and obese type 2 diabetes patients, as past research has linked weight loss with “improvements in glycemic control, risk factors for cardiovascular disease, quality of life, and other obesity-related coexisting illnesses.” But studies addressing the long term effects have been inconsistent, motivating Wing et al. to conduct their study.
Using 16 study centers in the United States, the researchers gathered information about 5,145 overweight or obese patients with type 2 diabetes. Participants had to be between age 45 and 75 years, have verification of the use of glucose-lowering medication, have a BMI >25.0 and a glycated hemoglobin level <11%, and be able to complete a minimal exercise test, amongst other criteria.
In an effort to obtain maximal generalizability of their results to the national population, the researchers included patients both with and without cardiovascular disease, and limited patients receiving insulin to under 30% of the sample group.
The patients were then randomly split up into an intervention group, which was subjected to reduced caloric intake and increased physical activity in an effort to maintain weight loss of at least 7%, and a control group, which merely received support and education about diabetes.
The 2,570 patients in the intervention group were held to a range of 1,200-1,800 kcal per day and at least 175 minutes of moderate-intensity physical activity per week.
The 2,575 patients in the control group went to three group sessions yearly regarding diet, exercise, and social support. After the first four years of follow up, the number of annual sessions was reduced to one.
The average patient age was 58.7 years and the average BMI was 36.0. Sixty percent of the sample population was female.
Initially, the study defined their primary outcome as death from cardiovascular causes, nonfatal MI, and nonfatal stroke, but later added hospitalization for angina into the list of cardiovascular events. The average follow-up period was 9.6 years.
The intervention group did show signs of improving health when compared to the control group; their mean weight loss after a year was 8.6% compared with 0.7% for the control group. In addition, the intervention group showed greater improvements in glycated hemoglobin levels, amongst other measured cardiovascular risk factors. Reductions in urinary inctoninence, sleep apnea, and depression were also present for the intervention group.
Yet when it came to the more severe primary outcome, no notable difference between the groups was observed. In the control group, 418 patients experienced a cardiovascular event, including death, for a rate of 1.92 per 100 people in a year. In the intervention group, 403 patients experienced a cardiovascular event, for a rate of 1.83 per 100 people in a year, which did not suffice for a significant difference.
Even when looking at other outcomes, such as hospitalizations for heart failure, carotid endarterectomies, and peripheral vascular diseases, no significant discrepancies were seen.
What improvements were seen also proved to be transient. By the end of the trial, the gap between weight loss had closed considerably, as the mean weight loss in the intervention group had dropped to 6.0% while that figure climbed to 3.5% in the control group.
The researchers wondered whether more severe weight loss was required to cause a decrease in risk of cardiovascular event, but also noted that imposing a stricter intervention would be a less realistic representation of actual patients’ efforts.
by Walker Harrison, an undergraduate student at Columbia University and editorial intern with Clinical Advisor.