Downer diabetes trial: Weight loss, exercise fail to reduce cardiovascular risk

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Overweight or obese adults with type 2 diabetes who lost on average 6 percent of their body weight over about 10 years were no less at risk of cardiovascular disease than people who received diabetes support and education. But the intensive lifestyle intervention did improve their glycated hemoglobin levels, according to results published June 24 in the New England Journal of Medicine.

The Look AHEAD (Action for Health in Diabetes) trial, a multicenter, randomized study that enrolled 5,145 patients in the U.S. between 2001 and 2004, was ended early in 2012 due to futility. Rena Wing, PhD, of Miriam Hospital in Providence, R.I., and colleagues designed the trial to evaluate an intervention that included caloric restriction and exercise for adults with type 2 diabetes and a body mass index of 25 or greater.

The primary outcome was the first occurrence of the composite of death from cardiovascular causes, nonfatal MI and nonfatal stroke; hospitalization for angina was added later. Median follow-up at the trial’s termination was 9.6 years.

At baseline, patient characteristics in the two groups were similar. After the first year, the intervention group achieved a mean weight loss of 8.6 percent vs. 0.7 percent in the control group. That gap narrowed over time, with a difference of 2.5 percent between the groups by the study’s end.

The intervention group showed greater improvement in glycated hemoglobin levels and all other measured cardiovascular risk factors at one year. That trend also diminished over time, although the improvement in the intervention group’s glycated hemoglobin levels stayed partly sustained.

The Look AHEAD researchers found no difference in the primary outcome at 9.6 years, with 1.83 events per 100 person-years in the intervention group vs. 1.92 in the control group.

The authors offered a few possible explanations for the results: the sustained weight loss may not have been great enough to have an impact on cardiovascular morbidity and mortality or an increased use of statins in the control group may have narrowed the difference between the groups.

Although the findings were not statistically significant, they added that there was a trend toward a lower event rate in patients in the intervention group who at baseline had no history of cardiovascular disease compared with the control group, and toward a higher event rate in patients in the intervention group with cardiovascular disease at baseline compared with the control group.