Diabetes and Endurance Sports

By Christine Gerbstadt, MD, RD
running on the road

Digital Vision./Photodisc/Thinkstock

Regular, moderate exercise can help to prevent Type 2 diabetes and reduce or slow complications from Type 1 or Type 2 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 improved body mass index and blood glucose control, and fewer hypoglycemic (low blood sugar) episodes while participating in endurance sports.

Before You Begin

When it comes to sports, diabetes management is always the first priority. First, talk to your diabetes doctor 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 specializing in sports and diabetes care.

When You Start

Avoiding hypoglycemia (low blood sugar) is important before, during and after endurance training. If blood sugar is 70 to 100 mg/dl before exercise, then a snack that includes 15 grams of carbohydrate is recommended. For exercise that lasts longer than 60 minutes, additional carbohydrate may be needed to keep blood sugar within a safe range. When starting an endurance sport, follow these five tips:

  1. Check your blood sugar frequently, and stay in the blood glucose range that you and your physician decide upon.
  2. Always carry a quickly absorbable form of glucose — glucose tablets, sports drinks, gels or energy bars — when training.
  3. Train with a partner until you are skilled at avoiding hypoglycemia.
  4. Wear a medical alert ID bracelet, or any medical tag that helps to alert paramedics or emergency responders of your diabetes and any additional important medical condition that may require immediate or special attention.
  5. 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. Urine color should be pale yellow throughout the day.

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. Consistent carbohydrate intake throughout the day is recommended and as well as including well-balanced meals that incorporate quality sources of carbohydrate, lean protein and healthy fat. Adjustments to medications, including doses of insulin, may also be required, but this should be done under the supervision of your physician.

Within 30 minutes after exercising, a carbohydrate snack can help prevent hypoglycemia, although low blood sugar can occur even hours after exercising. Eat a regular meal within two hours of exercising and continue to check your blood sugar regularly.

Fueling strategies for diabetes and endurance sports are highly individualized, so an RDN that specializes in sports nutrition can help with the development of an individualized meal plan.

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