TUESDAY, Sept. 30, 2014 (HealthDay News) -- For millions of overweight Americans, regular exercise remains a prime weapon against excess weight and the threat of type 2 diabetes.
However, a new study suggests that the battle may be tougher for some than for others, depending on their genes.
"While physical activity generally promotes good health, it may not be as effective for everyone when it comes to preventing or treating type 2 diabetes," said one expert, Dr. Ruth Loos, director of the Genetics of Obesity and Related Metabolic Traits Program at the Icahn School of Medicine at Mount Sinai, New York City.
While it's long been known that physical activity can cut diabetes risk, the influence of genes on this protective effect hasn't been clear, according to background information from the study.
In the study, researchers led by Dr. Yann Klimentidis of the University of Arizona examined interactions between physical activity, genetics and diabetes risk in more than 8,100 white Americans, including 821 with type 2 diabetes.
They found that exercise provided less protection against diabetes in people at high genetic risk for diabetes and insulin resistance.
Insulin resistance, a precursor to full-blown diabetes, is a condition in which the body produces insulin but does not use it efficiently.
The study was published Sept. 29 in the journal Diabetologia.
While certain diabetes-linked genes seemed to blunt the benefits of exercise for both men and women, women seemed most affected, the Arizona team noted.
Loos, who is associate editor at Diabetologia and helped edit the paper, called the findings "important."
"This study suggests that especially those who are genetically prone [to diabetes] may need additional preventive measures and more targeted treatment," she said.
However, she also noted that the study had certain limitations.
"The scientists only studied sports participation, which is only a small component of people's overall daily physical activity," Loos said. "Furthermore, the role of a healthy diet, another important component in the prevention of type 2 diabetes, was not examined, either."
Dr. Minisha Sood is director of inpatient diabetes at Lenox Hill Hospital in New York City. She said that because the study only focused on white participants, its findings might not apply to a broader population of patients. However, Sood added that the general conclusion -- that genes may play a role in how effective exercise is in preventing diabetes -- makes intuitive sense.
And she stressed that the findings are no reason for people battling obesity to give up on exercise.
"Genetic predisposition to insulin resistance or not, physical activity has a multitude of health benefits --including perhaps delaying or mitigating insulin resistance," Sood said. "Being 'hardwired' for insulin resistance should not serve as a reason to give physical fitness and [maintaining a healthy weight] a low priority."
The U.S. Office of Disease Prevention and Health Promotion explains how to prevent type 2 diabetes.