Helping Diabetes Patients Exercise Without Fear

Anne L. Peters, MD


October 09, 2017

Today I'm going to discuss exercise in individuals with diabetes. There are two papers I want to review. One is an American Diabetes Association (ADA) position statement on exercise,[1] published last year in Diabetes Care, that is incredibly good. It's a very comprehensive review of literature on exercise in people with diabetes. A lot of it is for type 2 diabetes, but some of it applies to patients with type 1 diabetes as well.

It's about as thorough a review as you are going to get. It really goes through all of the principles of exercise in people with diabetes, why people should exercise, and how to approach exercise. It's a very good reference.

The other article,[2] published in The Lancet and Diabetes & Endocrinology, was one I had the good fortune of being part of. It's about exercise in individuals with type 1 diabetes. To my knowledge, there has never been a thorough summary of the literature on exercise in individuals with type 1 diabetes, and trust me—not many studies look at this.

Hypoglycemia is the big reason that patients with diabetes do not exercise.

We give expert advice on how patients with type 1 diabetes should approach exercise, and we give a lot of suggestions for how to teach patients. Many of my patient referrals come see me because they say, "My diabetes is going well, but every time I exercise, I develop hypoglycemia." Hypoglycemia is the big reason that patients with diabetes do not exercise.

Basic Principles of Diabetes Management During Exercise

I take care of all sorts of people who exercise, from all ages and all walks of life. I've taken care of Olympic athletes, NHL hockey players, kids who play soccer, and 80-year-olds who go for walks.

The most important thing we need to think of for our patients on insulin is how to make sure they do not have too much insulin in their body when they start to exercise. We need to figure out how best to do this for each person.

In general, I do not necessarily want people to have to eat extra in order to exercise, because many of our patients are exercising to lose weight. We recommend that if patients are going to exercise within 90 minutes of a meal, they reduce the amount of insulin taken before the meal prior to exercise. If patients are on a pump, they can reduce the basal rate on the pump to give them less insulin over the duration of the time they are exercising.

The key to managing post-exercise hyperglycemia is for patients to avoid overcorrecting it.

While exercising, the patient may need to ingest additional carbohydrates. Depending on the length and intensity of the exercise, a patient may need to ingest 15 to 30 grams of carbohydrates for every 30 minutes of exercise.

After exercise, patients may say, "My blood sugar goes up." You know what? That very often happens, particularly for more stressful exercise, because catecholamine levels go up, causing blood sugars to rise. A lot of patients get very discouraged by this. They have a really intense tennis match and their blood sugar is 300 mg/dL afterwards.

The key to managing post-exercise hyperglycemia is for patients to avoid overcorrecting it. Basically, as soon as that individual becomes hydrated and cools down, their blood sugar level will come down on its own.

I tell patients that it is a good idea to do some low-intensity cool-down after they have done high-intensity activity. If they do, they will see that they do not need that much correction insulin. For this, I have them administer half a dose [of insulin] after exercise and eat a snack containing 30 to 60 grams of carbohydrates. This is for the short-term exercise period.

Delayed Hypoglycemia

Delayed hypoglycemia can happen 12 to 24 hours later, often overnight if a patient exercises in the morning. Many patients who exercise need to reduce their overnight insulin. This may mean reducing their long-acting insulin or reducing the overnight basal rate on their pump.

It's important to discuss this with your patients with diabetes, because there is such a clear approach to dealing with exercise. Most of the time, our patients feel at a loss. I think many providers do not have a rational approach to managing this.

The two articles help give a path for doing this and they provide information. For my patients who are interested, I give them the article from The Lancet because it can also give them some clues as to what to do.

Managing Blood Sugar During Bursts of Exercise

Finally, if patients do bursts of exercise or resistance exercise like weight training, it keeps blood sugar levels even or it raises blood sugar levels. For instance, if somebody wants to do 30 minutes of cardio and 30 minutes of resistance or weight training, they should do the resistance exercise first, because that will stabilize the blood sugar levels for the aerobic portion of their exercise.

Changing how people work out can help them achieve their glucose targets. We do not want patients to go low, first and foremost, nor become more variable, which also can happen after exercise. Their sugars are high, their sugars are low. They are going up and down.

What I help people do is take a rational approach to exercise. I explain how they should eat before exercise and what they should do with carbohydrates during exercise and afterwards. If we do this and follow the principles laid forth in these articles, we can help our patients exercise successfully. Frankly, I think all of us should be exercising whether we have diabetes or not.


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