In a decade-long evaluation of the effects of an intensive lifestyle intervention on cardiovascular morbidity and mortality, researchers gathered data on patients ages 45 to 75 years with type 2 diabetes and a body mass index (BMI) greater than 25 at 16 U.S. sites. The intervention group comprised 2,570 patients who received weekly group and individual counseling (less often after six months); the goal was a caloric intake of 1,200 to 1,800 kcal/day; patients used meal-replacement products and took part in 175 minutes of weekly physical activity of moderate intensity. The 2,575 patients in the control group took part, three times a year, in group sessions focusing on diet, exercise, and social support. The mean BMI at baseline in both groups was 36, and the average age was 59 years. Patients had had diabetes for a median of five years, and 14% had a history of cardiovascular disease. The median follow-up period was almost 10 years (the study was stopped early).

Weight loss in the intervention group was significantly greater than in the control group, with the largest difference seen at one year: 9% in the intervention group and 0.7% in the control group. At the end of the study, that gap had closed somewhat: the mean weight loss from baseline was 6% in the intervention group and 3.5% in the control group. Waist circumference reductions and fitness improvement were greater in the intervention group.

There were no significant differences between the two groups in cardiac mortality or morbidity: 403 intervention patients and 418 control patients met the criteria for the primary outcome: death from cardiovascular causes, a nonfatal myocardial infarction, a nonfatal stroke, or hospitalization for angina. However, greater reductions in cardiovascular risk factors (except for low-density lipoprotein cholesterol levels) were observed in the intervention group. The authors did note several positive results from the intervention, however: improvements in glycated hemoglobin levels; partial diabetes remission in some patients; decreased need for insulin; reduced urinary incontinence, sleep apnea, and depression; and improvements in quality of life, physical functioning, and mobility.

A companion editorial noted these improvements and that the weight loss and reductions in risk factors were less pronounced as the study progressed. It also noted that rates of hospitalization for angina, a somewhat unreliable outcome, were almost identical between groups, which may have obscured the benefit in other areas. The editorial also suggested that differences between groups may have been reduced because cardioprotective medication was made less necessary by the intervention, and therefore was used less. Although the cardiovascular benefits of the lifestyle intervention may have been modest, increased exercise and a reduced-calorie diet effectively reduced the burden of diabetes.

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