NEW YORK (Reuters Health) - People with type 2 diabetes show improvements in their physical and mental health-related quality of life after a year of participation in a weight management program, a report out this week in the Archives of Internal Medicine shows.

And those who were doing the worst at the study's outset showed the greatest increases in well being, Dr. Donald A. Williamson of the Pennington Biomedical Research Center, Louisiana State University in Baton Rouge and his colleagues found.

Williamson and his team had previously reported that participants in the 16-center Look AHEAD (Action for Health in Diabetes) trial lost 8.77 kilograms, on average, or 8.58 percent of their body weight, after a year in the program.

In the current study, they looked at how the intervention affected participants' quality of life related to health. Studies to date, the researchers note, have had mixed results on how lifestyle interventions affect obese people's health-related quality of life.

The 5,145 Look AHEAD trial participants were 45 to 74 years old at the beginning of the study. Williamson and his colleagues plan to follow them for up to 11.5 years.

Trial participants were randomized to a control group or a weight management program that included one individual and three group sessions for the first six months, during which participants replaced two meals and one snack with liquid shakes and meal bars.

For the following six months, the intervention included one individual and three group sessions per month, while study participants replaced one meal per day with a shake or meal bar. The program's aim was for people to lose at least 7 percent of their initial body weight and to exercise for at least 175 minutes more each week.

Control group participants attended three group sessions over the course of the year on nutrition, exercise and support.

After 12 months, the control group's physical health-related quality of life had gotten worse. But the intervention group showed significant improvements in their physical health-related quality of life and their mental health-related quality of life, as well as reductions in their scores on a test of depressive symptoms.

Participants with the worst scores in each of these three areas had improved the most 12 months later. However, the most obese individuals in the intervention group didn't show improvement in their physical health-related quality of life.

Further analysis found that weight loss, fitness improvements and reductions in physical symptoms accounted for some but not all of the increases in physical health-related quality of life.

This finding suggests that other factors, such as counseling, changes in the social environment or improved functional abilities, may be key variables that contribute to improved health-related quality of life that occurs with lifestyle modification and weight management in overweight and obese adults with type 2 diabetes mellitus, the researchers note.

Given that many people will likely regain at least some of the weight they lost, Williamson and his team adds, it will be critical to see if improvements in their health-related quality of life remain stable.

SOURCE: Archives of Internal Medicine, January 26, 2009.

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