The study by physical fitness experts at Johns Hopkins has been at the annual meeting of the American Association of Cardiovascular and Pulmonary Rehabilitation, in Indianapolis.
The research shows that high liver fat levels are common among people with type 2 diabetes and contribute to heart disease risk.
The study's lead investigator, exercise physiologist Kerry Stewart, Ed.D., says the rise in the number of people with nonalcoholic fatty liver, mostly due to obesity, signals "a dark trend" because the disease, also called hepatic steatosis, may lead to cirrhosis and subsequent liver failure and transplantation, even cancer, as well as increased risk of diabetes-related heart disease.
"People with type 2 diabetes have added reason to be active and to exercise, not just because it is good for their overall health, but also because our study results pinpoint a key benefit to trimming the fatty liver that complicates their illness and which could accelerate heart disease and liver failure," says Stewart, a professor of medicine and director of clinical and research exercise physiology at the Johns Hopkins University School of Medicine and its Heart and Vascular Institute.
A majority of the quarter-million people who die each year from all kinds of diabetes do so as a result of some form of heart disease or stroke. And excess body fat is known to increase the likelihood of potentially life-threatening illness because the fat leads to more inflammation in the artery walls, high blood pressure and elevated blood cholesterol levels.
In the study, 77 diabetic men and women in Baltimore, Md., were divided into two groups.
For a six-month period, half of the study participants were put through a moderate program of sustained aerobic exercise consisting of 45-minute sessions three times a week.
They could bicycle, run on a treadmill or take brisk walks. In addition, they lifted stacked weights for about 20 minutes, also three times a week, and not at a heavy-duty pace.
The other half of the participants were asked to avoid any formal aerobic fitness or gym classes.
Special magnetic resonance imaging scans performed at the start and end of the study showed much lower levels of liver fat in the active group, while levels remained the same in the nonexercising group (at 5.6 percent and 8.5 percent, respectively). Physical fitness exams were also done.