Diabetes is on the rise among Americans of all ages: 18 million people have some form of the disease; 41 million have pre-diabetes. The good news is that preventive measures can delay the onset of diabetes, and controlling weight and cholesterol, blood pressure and blood glucose levels can help prevent complications once diabetes is present.

Proper diet and exercise. Together they seem to be the prescription for many common health problemsÑ high blood pressure and cholesterol, heart disease, stroke and obesity. In fact, these two lifestyle interventions are recommended by health experts for reducing the risk of type 2 diabetes, a condition that also is affecting more and more adolescents who are exchanging outdoor activities for computer games, and carrots and yogurt for chips, cookies and soda.

A breakthrough study conducted by the National Institutes of Health in 2001 is the first major clinical trial to show that diet and exercise can delay diabetes. The trial, focusing on a diverse American population with higher than normal blood glucose levels, proved that a half hour of walking or other low-intensity exercise daily, combined with a low-fat diet, reduced the risk of developing type 2 diabetes by 58 percent. In addition, the participants lost five to seven percent of their body weight.

Why diet and exercise work

Weight loss resulting from diet and increased physical activity enables muscle cells to use insulin and handle glucose more efficiently, thus lowering diabetes risk. Lack of exercise can cause muscle cells to lose their sensitivity to insulin, which controls levels of sugar in the blood.

"Even if you don't lose weight, exercise will make you stronger and healthier," says endocrinologist Douglas Zlock, M.D., medical director of the John Muir Diabetes Center - Walnut Creek. "Healthy habits can definitely postpone the onset of diabetes even if they don't prevent it."

Mary Kelly, a certified diabetes educator at the John Muir Diabetes Center - Concord, is a firm believer that those with diabetes can develop a flexible care program with the help of a diabetes educator. "If something is important to your quality of life, don't salute and give up," she says, referring to developing a doable diet/exercise program and medication schedule that fit with one's lifestyle. "Exercise and diet can slow the progression of diabetes. They can prevent having to take medications, while helping control blood pressure and cholesterol levels and manage stress."

Avoiding other complications

Although cutting out fatty foods and sweets and motivating oneself to maintain a daily exercise program can take some discipline, the payoff is tremendous because people with diabetes are much more prone to developing other complications.

Heart disease is two to four times more prevalent in those with diabetes and the risk of stroke is two to four times higher; high blood pressure manifests itself in the majority of adults with the disease; and diabetes is the leading cause of kidney disease.

"Controlling glucose, blood pressure and blood lipids, along with preventive care for eyes, kidneys and feet can greatly reduce the chances of developing one of the many complications associated with diabetes," says endocrinologist Roy Kaplan, M.D., medical director of the John Muir Diabetes Center - Concord.

Early detection is key to preventing complications

"Detecting diabetes early by screening those at high risk, especially because many people do not exhibit symptoms, is key to preventing complications," Dr. Kaplan says. Those more predisposed to diabetes are Hispanic Americans, African-Americans, Native Americans and Asian Americans, older adults, women who have had gestational diabetes and people with a family history of diabetes. These groups are advised to be especially careful to monitor their lifestyle and follow the suggestions below.

Suggestions for delaying the onset of diabetes

Drs. Kaplan and Zlock recommend incorporating the following suggestions into a health care regimen:

1. Exercise at least 30 minutes a day.
2. Eat a low-fat, low-sugar diet rich in vegetables, fruits and whole grains.
3. Maintain your ideal weight through sufficient exercise and well-balanced meals.
4. Check your blood cholesterol at least once a year. Total cholesterol should be below 200, with LDL under 100, HDL (good cholesterol) above 45 and triglycerides below 150.
5. Keep blood pressure under controlÑat 130/80 or lower.
6. Avoid smoking; drink in moderation.