Diabetes and Exercise: What Role Does Nutrition Play?

Having Type I Diabetes is like constantly walking on a tightrope.

From a nutritional standpoint and knowing someone who is affected by diabetes, I can understand why this is such a struggle. Balancing insulin administration and carbohydrate consumption becomes very challenging; throwing in physical activity adds another hurdle. Physical activity has an impact on your blood glucose levels – also known as your blood sugar – which may be beneficial or detrimental. There is no one-size-fits-all nutrition plan for an athlete with diabetes.

The most common forms of diabetes are Type I Diabetes Mellitus (T1DM) or Type II Diabetes Mellitus (T2DM). T1DM is an autoimmune disease where insulin-producing cells in the pancreas are attacked. Typically, people are diagnosed at an early age. T2DM is a metabolic disease where insulin resistance is present – a lowered response to insulin – as well as a decrease in insulin secretion. According to research, individuals with a higher body weight are more prone to developing T2DM and other related diseases.

How would you know if you have diabetes? Diagnosis of diabetes can be determined by a fasting blood glucose level above 125mg/dL or a hemoglobin A1C higher than 6.5%. There are many influences that can cause your blood sugars to rapidly increase or decrease, which is known as hypo- or hyperglycemia.

Hypoglycemia measures a blood glucose level of less than 70mg/dL, which may result in blurred vision, dizziness, headache or low energy. A reduced intake of carbohydrates or elevated insulin production could cause hypoglycemia. A blood sugar level higher than 180mg/dL results in hyperglycemia. Signs or symptoms include nausea, dehydration, a fruity odor in the breath from ketone production or frequent urination. With low insulin and a high carbohydrate load hyperglycemia will occur, as it would with a short-duration, high intensity workout.

So how does having diabetes affect the way you perform and eat? I’d like to say it’s fairly simple, but there are many obstacles to overcome. Similarly to the average person, it’s recommended that someone with diabetes should aim for about 150 minutes of physical activity per week. The advantages of incorporating physical activity to your daily life include improved blood glucose levels, increased insulin sensitivity and possible weight management. Some things to consider before a workout:

  • Where are your blood sugars at?

  • How intense is your planned activity?

  • How long do you plan on exercising?

  • What are your planned insulin doses?

Distributing carbohydrates throughout the day will optimize performance. Oftentimes, athletes will consume large, carbohydrate-rich meals when their insulin sensitivity is at its highest – evening or post-workout. If you’re unable to eat during an event and know your blood sugar pattern, you may prefer a slightly elevated blood sugar when exercising. Why would this be? Short duration workouts release glucose from the liver to fuel the muscles, leading to a higher blood sugar level. Insulin then brings glucose to the muscles to be used as an energy source. Think of it as exercise opening the cell and insulin opening the door to the cell – allowing glucose in. Incorporating carbohydrates during a longer workout will provide efficient energy to the muscle. This can include whole foods or liquids like Gatorade for a fast-acting response.

Best choices of carbohydrates include:

  • Fruits (apples, strawberries, grapes)

  • Vegetables (potatoes, corn, beets)

  • Grains (rice, quinoa, oats)

  • Dairy products (milk, yogurt, cottage cheese)


  1. Diabetes.org https://www.diabetes.org/fitness/get-and-stay-fit/exercise-and-type-1

  2. Sports, Cardiovascular, and Wellness Nutrition Dietetic Practice Group, Rosenbloom, C., & Coleman, E. (2017). Nutrition for athletes with diabetes. Sports nutrition: A handbook for professionals. (pp.420-437) Academy of Nutrition and Dietetics

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