The ACSM recommends that people with diabetes gradually work up to 30 minutes of exercise a day — possibly broken into three 10-minute sessions — at least three nonconsecutive days a week, and preferably most days of the week. Exercise more often or for longer periods of time if you are willing and able, but remember not to overdo it. A simple rule of thumb is that you may be overdoing it if you do not have the breath to carry on a conversation as you exercise. Experiencing a loss of strength or feeling burned out or fatigued are also signs that you may be overdoing the exercise.
Resistance training. While aerobic activity is a good base for exercise, the ACSM advises adding some light resistance or weight training twice a week to add variety and increase your calorie-burning muscle mass. High-intensity resistance training with heavy weights is not recommended for some people with diabetes, but light weights with more repetitions may be fine. If you have retinopathy, however, check with your eye doctor before starting any resistance training.
To prevent accidents and injury, learn how to do resistance exercises properly under the guidance of a certified trainer, or ask your physician to refer you to an exercise physiologist. In addition to helping with diabetes control, resistance exercise may be particularly effective at staving off osteoporosis.
Exercise safety. While recommendations from the Surgeon General and various health organizations say everyone can benefit from some exercise, make sure you exercise safely by consulting with your physician before beginning an exercise regimen. Your doctor should give you a complete physical to assess your risk for diabetes-related complications and may prescribe a stress test and a dilated eye exam. People with high blood pressure may be advised to avoid exercises such as lifting that raise blood pressure, while people with nerve damage may be advised to do more swimming or biking than running.
Before each exercise session, be sure to check your blood glucose level. If it is below 100 mg/dl, consume 15 grams of carbohydrate to raise your blood glucose level before beginning your workout to prevent hypoglycemia during the workout. High blood glucose before exercise merits some caution, as well. While exercise is said to have an insulin-like effect (in that it generally lowers blood glucose), if there’s not enough actual insulin in the body, blood glucose levels may rise with exercise. If your blood glucose is above 240 mg/dl, start exercising and check your blood glucose after 15 minutes. If the level has gone up, stop your activity and drink some water; speak with your diabetes educator to learn what to do in this situation since you may need to take insulin, as well. If your blood glucose level has decreased, feel free to continue.
If you have Type 1 diabetes and your blood glucose level is above 300 mg/dl, drink water and test your urine for ketones. If urine ketones are present, there’s a risk of ketoacidosis and coma, so call your physician or diabetes educator for advice on how to proceed.
If you’re planning to exercise for over half an hour, plan on checking your blood glucose at half-hour intervals. Carry some glucose tablets or other carbohydrate to treat hypoglycemia. Depending on how strenuous your workout is, blood glucose levels can be affected up to 24 hours after exercise. Plan on checking your blood sugar several times after exercise until you learn how the exercise affects your body and your blood glucose levels.