THURSDAY, May 8 (HealthDay News) -- Arthritis strikes more than half of the 20.6 million American adults who have diabetes, and the painful joint condition may be a barrier to exercise among these patients, a new government report shows.

Being physically active helps people manage both diseases better by controlling blood sugar levels and reducing joint pain, according to the report in the May 9 issue of Morbidity and Mortality Weekly Report, a publication of the U.S. Centers for Disease Control and Prevention.

"The prevalence of arthritis is astoundingly high in people with diabetes," said Dr. John H. Klippel, president and CEO of the Arthritis Foundation. "Over half the people with diabetes have arthritis."

Although there appears to be a connection between arthritis and diabetes, the reason for it isn't known, Klippel said. A possible explanation is obesity, which is a risk factor for both osteoarthritis and diabetes, he speculated.

"In addition, those individuals who have diabetes and arthritis are less physically active," Klippel said. "We know that physical activity is critically important for the control of diabetes, both for the control of blood glucose and the prevention of complications."

Using data from the Behavioral Risk Factor Surveillance System, CDC researchers found 29.8 percent of people with both diseases were more likely to be inactive, compared with 21 percent of those who only have diabetes, 17.3 percent of those with arthritis alone, and 10.9 percent of those with neither condition.

For people who suffer from both diabetes and arthritis, arthritis appears to be a barrier to being physically active. But being physically active by doing aerobic exercise, strength training, walking, swimming or biking can benefit people with both diseases, according to the CDC.

"Public health efforts to control diabetes are going to have to begin to pay attention to this problem of arthritis, if we ever hope to get people physically active," Klippel said.

Klippel thinks the importance of physical activity needs to be emphasized. "Many people with arthritis don't exercise because it hurts them. But they have to understand that if they exercise, it will actually reduce their pain and prevents the disease from progressing," he said.

One of the keys to controlling diabetes is exercise, Klippel stressed.

"People with diabetes are going to have to pay a lot more attention to their arthritis if they hope to achieve better control of their diabetes," Klippel said. "People with arthritis are going to have to recognize that there is an association between diabetes and arthritis."

For people with arthritis and diabetes, the Diabetes Foundation recommends getting physically active by taking a walk at least three days a week.

The foundation recommends starting with a 10-minute walk, increasing it to 30 minutes over time. Before taking that walk, it's important to stretch your legs, lower back, chest and arms, Klippel said.

To keep yourself motivated, walk with a friend, the foundation suggests.

In addition, maintaining a healthy weight will place less stress on joints, particularly the knees. Also, being overweight can cause you to tire more quickly and give up on your exercise program.

More information

For more on arthritis, visit the Arthritis Foundation.

SOURCES: John H. Klippel, M.D., president and CEO, Arthritis Foundation, Atlanta; May 9, 2008, Morbidity and Mortality Weekly Report, U.S. Centers for Disease Control and Prevention