Health Effects of Diet and Exercise for Adults with Type 2 Diabetes and Obesity
Researchers in the Look AHEAD (Action for Health in Diabetes) clinical trial found that an intensive lifestyle intervention for weight loss was not sufficient to stave off heart disease and stroke in overweight and obese adults with type 2 diabetes, but it did yield a number of other health benefits.
Because type 2 diabetes is a devastating disease, increasing risk for cardiovascular disease and other complications, and because obesity also heightens risk for many diseases and disorders, researchers have been exploring ways to improve health for individuals with these conditions. Based on prior, short‑term studies, weight loss has been recommended for overweight and obese patients with type 2 diabetes, but the effects on cardiovascular disease (CVD) over the long term had not been known. To conduct the Look AHEAD clinical trial, investigators at 16 centers around the United States recruited 5,145 volunteers. The participants were women and men of diverse racial/ethnic backgrounds, ages 45 to 75 at the start of the study, who had type 2 diabetes and were overweight or obese. The researchers designed a lifestyle intervention that aimed for a seven percent weight loss through decreased calorie intake, and in particular, reduced calories from dietary fat, along with 175 minutes of moderate intensity physical activity per 50 NIDDK Recent Advances Emerging Opportunities: Obesity week. The intervention included regular group and individual counseling sessions, liquid meal replacement products for some meals, and a toolbox of additional strategies to assist those having difficulty with weight loss. Half of the participants were randomly assigned to receive this lifestyle intervention. For comparison, the other half of the participants were assigned to a much less intensive program of diabetes support and education, comprised of several group sessions focused on diet, exercise, and social support. For all participants, the investigators recorded CVD events: instances of death from any cardiovascular cause, non‑fatal heart attack or stroke, and hospitalization for a condition called angina. They also monitored other health conditions.
After nearly 10 years of follow up, the researchers found that the numbers of CVD events were not significantly different between the intensive lifestyle intervention group and the diabetes support and education group. This similar number of CVD events was observed even though there were improvements in a number of disease risk factors in the lifestyle intervention group, with less use of medication. These benefits included greater weight loss; improved blood pressure; increased fitness, as measured by an exercise test; and improved blood glucose (sugar) control.
Additional analyses of data from the first several years of the Look AHEAD trial have identified many other health benefits of the lifestyle intervention. For example, the researchers investigated whether the intervention led to partial or complete remission of type 2 diabetes over the first four years of the study, and, as reported recently, they found that it did, although at modest rates. After one year, about 11.5 percent of those in the intervention group experienced at least partial remission of their diabetes, as defined by blood glucose levels decreasing to prediabetes or normal levels without need for diabetes medications. By the fourth year of the study, 7.3 percent of participants in the lifestyle intervention had at least partial remission of their diabetes. Those in the control group experienced a smaller remission rate of only two percent at both time points. Remission in the intensive lifestyle intervention group was more likely among those who had lived with diabetes for less than two years at the study’s outset, and who had relatively low (although still diabetic) glucose levels, did not yet need insulin therapy for their diabetes, and had greater weight loss and fitness improvements during the study. The association between remission and shorter duration of type 2 diabetes suggests that starting healthy lifestyle changes early in the course of the disease may lead to better outcomes.
In another recently reported analysis, researchers analyzing the first four years of Look AHEAD data found that the lifestyle intervention reduced levels of obstructive sleep apnea, a serious breathing disorder during sleep that is associated with obesity. Among other benefits, researchers have previously reported a decrease in urinary incontinence, improvements in quality of life, and less of a decline in physical mobility as a result of the lifestyle intervention. At this point, because there was not a reduction in CVD events, the intervention phase of Look AHEAD has concluded. However, researchers are continuing follow up of the study participants to evaluate longer‑term effects. This research will help inform decisions about management of type 2 diabetes, to help people improve their health and quality of life.