For many diabetics, exercise can work wonders, just like it does in nondiabetics. It can provide a general sense of well-being and help to prevent cardiovascular disease. To understand how exercise works in diabetes, we must first understand the mystery of sweetness.

Generally, untreated diabetics have high levels of sugar (or glucose) in the blood. In a normal body, extra blood sugar is absorbed into other tissues, such as muscle cells. A fine-tuned mechanism helps to keep enough sugar in the blood to nourish the brain while removing any surplus sugar. This mechanism is defective in people with diabetes type I and II.

In type I diabetes (juvenile diabetes), insulin is not produced. Insulin is essential to transport the sugar away from the blood into other tissues. These individuals must therefore take insulin injections to compensate.

Enter exercise, which also helps to transport sugar away from the blood. People with type I diabetes are now at risk of having too much sugar removed from the blood. They must take the following precautions:

• Monitor blood glucose carefully — before, during and after exercise.
• Adjust diet and insulin dosage, with the help of a doctor. A waiting period of one to two hours after insulin injections or meals taken with insulin is recommended. This ensures that exercise does not remove blood sugar at the same time as insulin does. It may also be necessary to reduce the dose of insulin before and after exercise.
• Exercise at the same time every day to make it is easy to manage insulin and glucose levels.
• Choose activities that require little intensity and duration. If you exercise longer than 30 minutes, eat carbohydrates like dextrose or chocolate every half hour.

For their part, people with type II diabetes have much to gain from exercise. Type II diabetes often develops during adulthood, especially in obese people, those with high blood pressure and those with a family history of diabetes. Approximately 90% of all people with diabetes suffer from type II diabetes.

Some type II diabetics have a low insulin production. Others, who tend to be obese, secrete enough insulin, but their muscle cells resist the action of insulin and "refuse" to absorb surplus blood sugar.

Exercise is an effective treatment for type II diabetics, particularly those who have no other interfering disease. It works in two ways:

• by improving glucose control in individuals who have a low insulin production;
• 
  by contributing to weight reduction in overweight diabetics (when combined with an appropriate diet). Weight reduction leads to an increased willingness on the part of muscle cells to respond to insulin by absorbing surplus blood glucose.

The best activities for overweight diabetics are those with a low intensity and longer duration — walking, for example. In fact, low-intensity activities burn off a higher percentage of fat than high-intensity ones! All you need to do to burn off as many calories is exercise longer.

Exercise is also effective in preventing diabetes. Individuals at risk of developing diabetes have a lot to gain from making a habit of a regular, enjoyable exercise.