The Diabetic Athlete: Measure, Manage, Log

Correctly matching fuel intake to your run before, during, and after exercise is a challenge that becomes even more important for the diabetic athlete.


Fuel efficiency and performance is optimized when blood glucose concentrations range between 70 mg/dL to 180 mg/dL. Levels which are higher or lower may result in fatigue, poor concentration, nausea and poor performance. Due to the risk of hypoglycemia (low blood sugar), many athletes prefer a blood glucose concentration of 120 mg/dL to 180 mg/dL.

Maintaining a diary of food and fluid intake, activity type and length, medication and blood sugar response is an important step towards optimizing your athletic performance while reducing side effects related to diabetes. Before exercise, diabetics should monitor their blood glucose at 90, 60 and 30 minutes to determine the trend in comparison to their pre activity food and fluid intake. If blood glucose is < 65mg/dL to 100 mg/dL the runner should consume 15 grams of carbohydrate. If blood glucose is more than 250 mg/dL , the athlete should check for the presence of ketones, not exercise if ketones are present, and may need to administer insulin. During exercise, they should measure blood glucose every 30 minutes as well until they are able to achieve a good, consistent response. After exercise, measuring blood glucose at 2 and 4 hours is recommended, especially if individuals have a history of post exercise hypoglycemia. Note, low blood sugar can persist for up to 24 hours after exercise so continued monitoring is essential. Bring your diary to your next medical appointment.

These tips are not meant to be a substitution or replacement for the diabetic management prescribed by your health care practitioner. Diabetic athletes with questions are encouraged to follow up with their physician and a Registered Dietitian knowledgeable in sports and diabetes nutrition. Source: Nancy Clark, MS RD, CSSD Sports Nutrition Guidebook, Jackie Berning, PHD, RD, CSSD, Michael McDermott, PhD, RD, CSSD and Roberta Anding, RD, CDE, CSSD Advanced Strategies for Counseling Athletes with Type 1 Diabetes, SCAN’s Pulse Spring 2010.