By Christine Gerbstadt, MD, MPH, RDN
Regular, moderate exercise can prevent, reduce or slow complications of diabetes. But what about more intense physical activity with endurance sports such as marathons or triathlons? With healthy training and nutrition management to meet your personal diabetes goals, you can achieve athletic success, improved body mass index and blood glucose control, and fewer hypoglycemic (low blood sugar) episodes while participating in endurance sports.
Before You Begin
Diabetes management is always the first priority. Before you lace up your sneakers, talk to your diabetes doctor. Ask about an insulin pump, continuous glucose monitor (CGM) and pre-training medical testing. Determine your safe blood glucose range for training and competing. Once you've gotten the go-ahead from your doctor, consult a registered dietitian nutritionist (RDN) specializing in sports and diabetes care.
When You Start
Avoiding hypoglycemia (low blood sugar) is important before, during and after endurance training. If low blood sugar results while exercising, the Academy of Nutrition and Dietetics recommends that blood sugar return to 100 mg/dL before resuming exercise. Also, if using insulin, never start intensive endurance exercise within the week after severe hypoglycemia — symptoms of severe hypoglycemia may include sweating, heart palpitations, mental confusion and seizures. When starting an endurance sport, follow these five tips:
- Check your blood sugar frequently, and stay in the blood glucose range that you and your physician decide upon.
- Always carry a quickly absorbable form of glucose — glucose tablets, sports drinks, gels or energy bars — when training.
- Train with a partner until you are skilled at avoiding hypoglycemia.
- Wear a medical alert ID bracelet, or any medical tag that helps to alert paramedics or emergency responders of any important medical condition that may require immediate or special attention.
- Eat and drink before, during and after exercising. Hyperglycemia is worse with dehydration, and high blood sugar levels can cause the body to lose additional water.
Eat Right for Optimal Blood Glucose Control When Training
Plan meals, snacks and beverages to meet your blood glucose targets, and make adjustments depending on how your blood sugar is responding to your training.
Before: Eat a small snack, about 200 calories, of complex carbohydrates with some protein and fat. For example, ½ cup oatmeal and ½ cup fat-free milk or a slice of whole-grain bread with a tablespoon of peanut butter (15 grams carbs / 7 grams protein / 9 grams fat.) Experiment with consuming fiber while training.
During: At 45 to 60 minutes into your activity, eat 15 grams of simple carbohydrates such as an 8-ounce sports drink, a half of a banana, a small handful of raisins or commercially-prepared carbohydrate replacements (i.e.: sport gels or gumdrops).
After: Prevent hypoglycemia by eating enough food immediately after endurance training. Within 15 minutes, eat a post-workout snack, such as 6 ounces of non-fat yogurt and a small apple (35 grams carbs / 7 grams protein) or a homemade or commercially-prepared protein bar. Eat a regular meal within two hours; check your blood sugar frequently. Exhaustion after training may hide your hypoglycemia.
Fluids: Drink water before, during and after exercising; have 8 to 16 ounces before exercise, and continue drinking water during and after physical activity to replenish the fluid that was lost. You should have clear urine within 2 hours of completing your activity. If it's still dark colored, keep drinking water until it is clear.