Diabetes study affirms long-term benefits of exercise

From post-gazette.com

When it comes to preventing and treating Type 2 diabetes, losing 7 percent of body weight and briskly walking 150 minutes a week can do more than drugs.
But the problem always has been dedication to task — persuading people that weighing less and exercising more now and forever after will help them avoid the health burdens diabetes can impose.
If you lose weight, keep it off. If you exercise, keep it going.
Now a University of Pittsburgh study published in the American Journal of Preventive Medicine shows that a percentage of people who participated more than a decade ago in the Diabetes Prevention Program continued exercising more than the average person of similar age and health circumstances.
In the study, members of that same group 10 years later were compared with the general population of similar age and health challenges, based on data from the National Health and Nutrition Examination Survey, known as NHANES. It also used ActiGraph accelerometer readings to document exercise levels, rather than the self-report questionnaires that were previously used.
Overall, the study found that “lifestyle intervention was effective at increasing moderate physical activity more than 10 years into the [prevention program] follow-up,” noting that the program succeeded in “achieving long-term improvements in moderate activity levels.”

“What we ended up finding from accelerometer data was some evidence of a lasting effect, as the [prevention program] participants had higher physical activity levels than the general population,” said study author Bonny Rockette-Wagner, University of Pittsburgh Graduate School of Public Health director of physical activity assessment in its department of epidemiology.
Planted on the couch
The landmark Diabetes Prevention Program study, published in 2002, was important in showing that those who achieved modest weight loss and regularly exercised had a 58 percent higher rate of success in preventing diabetes than the baseline group, which did not participate in a weight loss/​exercise program or use diabetes drugs. Those placed on metformin, the most commonly prescribed Type 2 drug, had a 31 percent success rate as compared with the baseline group.
To the surprise of many, exercise and weight loss did better than drugs in preventing diabetes.
And in the current Pitt study, while original participants did exercise a bit more than the general public, there’s still room for improvement.
For example, participants 10 years later were sedentary for more than 9 hours a day with 4½ hours of light physical activity — such as housework or walking to the mailbox — and slightly more than 15 minutes a day in moderate to vigorous physical activity.
But this study also found that the study group and general population had similar levels of sedentary behaviour — a major research focus these days due to the potential risk factor for chronic disease.
Sedentary behaviour generally increases and exercise declines with age, as might be expected. People with diabetes also were less physically active than those without diabetes, the study showed.
“Our participants we thought would have higher activity and lower sedentary behaviour than people in the general populations,” said Ms. Rockette-Wagner, who holds a Ph.D. in epidemiology. “But there was not much difference in sedentary behavior.”
Limits on downtime
The Pitt study, covering an expanse of time rare for such studies, represents the latest research to support lifestyle changes to avoid known causes of Type 2 diabetes, which include weight gain, poor diet and a sedentary lifestyle.
The Pitt-based team was led by Andrea Kriska, a Pitt Public Health epidemiology professor who also led development of the physical activity component of the Diabetes Prevention Program and analysed its impact. She also was part of the team of prevention-program investigators in Pittsburgh who modified its lifestyle intervention procedures for a more community-friendly program called Group Lifestyle Balance, or GLB.
Her previous study funded through the National Institutes of Health tested the GLB program in high risk adults from three different community settings, including senior centres of varying socioeconomic status, a work site and a military base. The results, she said, were “a resounding success,” with impacts on weight loss and physical activity while also showing that the intervention improved several diabetes and cardiovascular risk factors in the 286 participants from the diverse community sites.
Gaining a better understanding of the health impact of reduced sitting time is the focus of the Kriska/​Rockette-Wagner team, with an NIH-funded study to examine whether the beneficial changes in weight loss, diabetes and cardiovascular risk factors will be seen if the goal is shifted from moderate physical activity to sitting less.
Such results already were suggested in the original Diabetes Prevention Program.
The two researchers also led another study that found that each hour spent watching television daily increases the risk of developing diabetes by 3.4 percent. Reductions in sitting time appear to translate into a positive health effect separate from improvements to moderate-vigorous activity, that study said.
Ultimately, a person may be unable to continue exercising or maintaining weight loss indefinitely, but the longer the better, said Ms. Kriska, who also holds a Ph.D. in epidemiology, noting the many modern-day lifestyle challenges that include television, computers and smartphones.
Next on the agenda, she said, is determining a limit for sedentary behaviour. Until that’s established, it’s a good idea to try breaking up long periods of sitting and reducing total sitting time, with evidence from other studies showing that even reducing sitting time by 30 minutes a day could benefit health.

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