If you have
, exercise can help keep blood sugar under control and promote good health. However, there are precautions you should know about. While exercise is beneficial because it can lower your blood sugar level, it can also be dangerous for the same reason. Exercise can lead to
—a quick drop in blood sugar.
The Importance of Balance
type 1 diabetes
requires a balance of eating, exercising, and insulin usage to keep blood sugar levels within a desirable range. People without diabetes rarely give blood sugar a thought. This is because the pancreas automatically produces insulin to escort sugar out of the bloodstream and into body cells for use. Insulin production is naturally matched with the amount of sugar in the blood to keep levels stable.
However, with type 1 diabetes your body does not produce insulin. Therefore, you must take over as the regulator of blood sugar. This is an important job, as both high and low blood sugar levels can have serious health consequences.
type 2 diabetes
, your body produces insulin, but it either can’t use it properly or doesn’t make enough. People who manage type 2 diabetes with meal planning and exercise usually do not have problems with hypoglycemia. But if you use insulin injections, you may be at risk for exercise-induced hypoglycemia.
What Is Hypoglycemia?
During exercise, your muscles take up sugar from the bloodstream to convert into energy. Such usage can decrease blood sugar to dangerously low levels (70-90 mg/dL [3.9-5.0 mmol/L] depending on the meter used; check with your doctor). This hypoglycemia can occur quickly. Symptoms include shakiness, dizziness, sweating, headache, hunger, pale skin, sudden moodiness, clumsy movements, confusion, and tingling around the mouth. Severe hypoglycemia can result in unconsciousness or seizures.
But don’t let the risk of hypoglycemia keep you from the many benefits of exercise. With a few precautions, you can reestablish the balance of food, exercise, and insulin. The American Diabetes Association (ADA) and the Joslin Diabetes Center recommend these guidelines for safely incorporating exercise into your lifestyle:
Talk to Your Healthcare Team
Your healthcare team can personalize your exercise goals. If you are over age 35, have had diabetes for more than ten years, or have other cardiac disease risk factors, your doctor will do an exam and some testing to determine what type of exercise is safe for you.
Time It Right
Schedule exercise at the same time each day. The best time is 1-3 hours after a meal. This is when blood sugar levels are highest, and the risk of hypoglycemia is lowest.
Monitor Your Blood Sugar Closely
Check your blood sugar before, during, and after exercise, and record these numbers. You and your healthcare team can use these readings to determine any changes in your insulin dose; with regular exercise, your need for insulin may decrease.
Before exercise, check your blood sugar twice: 30 minutes before and a few minutes before. This way, you’ll see if your blood sugar is decreasing. If it is dropping or it is 100 mg/dL (5.6 mmol/L) or less, have a small snack and wait for blood sugar to return to normal. People with type 2 diabetes may be advised to avoid extra snacking, because it may interfere with weight loss (ask your doctor). If your blood sugar is high—250 mg/dL (13.9 mmol/L) or more—do not exercise. Instead, check your urine for ketones. Do not exercise until both blood sugar and ketone levels return to normal.
During exercise, check every 30 minutes. If blood sugar levels drop too much (ask your doctor what level is too low), stop exercising and have a snack. Also be aware of high levels. Ask your doctor when to check for ketones and how best to manage high blood sugar.
After exercise, check again. If your exercise session is long, check regularly for several hours after, as blood sugar may continue to drop.
Always have blood testing equipment, insulin, and high carbohydrate snacks with you. Good snacks include juice, soft drinks, glucose tablets or gel, raisins, or hard candy. If hypoglycemia is a recurring problem, ask your doctor about a glucagon injection kit to treat a severe case. Carry a water bottle and drink often.
If you have eye damage (retinopathy), avoid high-impact exercise that involves straining such as racquet sports, jogging, and lifting heavy weights. Better choices include walking, swimming, riding a stationary bike, and lifting light weights. Also, you may want to exercise indoors in a well-lit gym.
To protect your feet, check for blisters or other changes after every workout. Choose low-impact activities such as swimming and cycling, rather than high-impact ones such as jogging or step exercises. Buy footwear appropriate for the sport and fit well to your feet. Wear clean, smooth-fitting socks (made with synthetic fibers, not all cotton).
The many benefits of exercise, from reduced stress and decreased risk of diabetes-related complications to overall better health far outweigh the inconvenience of the precautions. So find an activity you enjoy and get moving!
Please be aware that this information is provided to supplement the care
provided by your physician. It is neither intended nor implied to be a
substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER
IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the
advice of your physician or other qualified health provider prior to
starting any new treatment or with any questions you may have regarding a