Whether you have diabetes or want to avoid it, you have every reason to be physically active. Working muscles use up glucose at a rate 20 times greater than usual. If you're not taking insulin, your insulin levels also drop when you're exercising, so you're not at risk of high or low blood sugar.
Talk to your doctor before you start exercising. A physical examination might be needed to assess the type and severity of complications, particularly those involving small and large blood vessels or peripheral nerves in the legs and feet.
Mild to moderate aerobic activity — brisk walking, swimming, biking and running — is ordinarily recommended for type 2 diabetics because of its stabilizing effect on blood sugar. Non-weight-bearing exercises are suggested for people with neuropathy who want to avoid foot sores.
Strength training also is recommended, but those with severe diabetic eye disease might have to avoid heavy weightlifting that causes strain and an increase in blood pressure.
Optimal benefits occur with the combination of aerobic exercise and strength training. The beneficial glucose-lowering effects and improved insulin sensitivity resulting from exercise deteriorate within 72 hours of the last session. Take a day off, or even two, but not three in a row.
If you are taking insulin or other medications that can lower blood sugar, follow some guidelines to assure a safe blood-sugar level.
Before exercise: Test your blood sugar 30 minutes before exercising. If your level is 100 to 250 mg/dL, you're safe to exercise, but if it's lower than 100 mg/dL, you need to boost your blood sugar with a small carbohydrate snack, such as fruit or crackers. Postpone your workout if your reading is higher than 300 mg/dL.
During exercise: If you work out more than 30 minutes, test your blood sugar again, particularly if you're starting a new activity or changing intensity or duration. If your blood sugar drops below 70 mg/dL or if you feel shaky, nervous or confused, stop immediately and eat or drink something. Then recheck your blood glucose every 15 minutes until your blood sugar reaches and stays at a safe level.
After exercise: Check your blood glucose immediately and again several times during the next few hours until it is stable. The longer and more strenuous your workout, the longer you are at risk of hypoglycemia (low blood sugar).
Physical activity can temporarily complicate good blood glucose control for some patients, but that's no reason to stay on the couch.