Exercise and Type 1 Diabetes

Regardless of the type of diabetes you have, regular physical activity is important for your overall health and wellness.

With type 1, it’s very important to balance your insulin doses with the food you eat and the activity that you do – even if you are just doing house or yard work. 

Planning ahead and knowing your body’s typical blood glucose response to exercise can help you keep your blood glucose from going too low or too high.

Preventing Lows

Your blood glucose response to exercise will vary depending on:

  • your blood glucose level before starting activity,
  • the intensity of the activity,
  • the length of time you are active,
  • and changes you’ve made to insulin doses.

Sometimes people experience a drop in blood glucose during or after exercise, so it is very important to monitor your blood glucose, take proper precautions, and be prepared to treat hypoglycemia (low blood glucose).

To learn how different types of activity affect you, you should frequently check your blood glucose before, during, and after an exercise session.

Put a trial and error system into place. For example, increased activity may mean that you need to lower your insulin dose or eat some extra carbohydrates before exercising to keep your blood glucose in a safe range. Some activities may cause your blood glucose to drop quickly while others do not. 

If your blood glucose levels are trending down before a workout, have a pre-exercise snack. Always carry a carbohydrate food or drink (like juice or glucose tabs) that will quickly raise your blood glucose. It may take a while to figure out what works best for you. 

If your blood glucose level is less than 100 mg/dl before you start your activity, try having a small carbohydrate snack (about 15 grams) to increase your blood glucose and reduce your risk for hypoglycemia. This is especially important if you anticipate that your body’s circulating insulin levels will be higher during the time you exercise and if you will be exercising for longer than 30 minutes.  

If you use an insulin pump, you may be able to avoid adding an extra snack by lowering your basal insulin rate during the activity.

If you have repeated problems with your blood glucose dropping during or after exercise, consult your doctor.   

To learn about how to treat low blood glucose during exercise, go to Blood Glucose Control and Exercise.

And check out the page Hypoglycemia (Low Blood Glucose) to learn more about the symptoms of hypoglycemia.

When Your Blood Glucose is High…

Blood glucose can also run high during or after exercise, particularly when you do a high-intensity exercise that increases your stress hormone (i.e., glucose-raising hormone) levels.

If your blood glucose is high before starting exercise, check your blood or urine for ketones. If you test positive for ketones, avoid vigorous activity.

If you do not have ketones in your blood or urine and you feel well, it should be fine to exercise.

Your Healthcare Team’s Role

Your healthcare team can help you find the balance between activity, food, and insulin.

When testing on your own to learn about your reaction to different activities, keep a record of your activity and your numbers. Your healthcare team can use that data to suggest adjustments and refine your plan.

If you are having chronic lows or highs, they may need to alter your insulin dose or make a change in your meal plan.

Learn about Exercise Needs Through the Life Span for people with type 1 diabetes.

Personal Stories from The Type 1 Diabetes Self-Care Manual by Jamie Wood, MD and Anne Peters, MD

Type 1 Diabetes Self-Care Manual

There’s No Way to Be “Perfect”

Running with type 1 diabetes is always a complicated challenge. Since every run is different, your blood sugars will never react exactly the same each time. You’ll go into the run with different amounts of food and insulin in your system, you’ll run at different paces and start at different times, you’ll run at different inclines or take different length breaks. The key is knowing you won’t get it right every time and to keep checking your blood sugar to stay on top of any changes. A continuous glucose monitor makes running so much easier I can’t imagine ever running without one. 

For me, there is always a strong desire to eliminate as many variables as possible: waking up at the same time every day, eating the same thing for breakfast, working out at the same intensity. And while it will make parts of type 1 diabetes less complicated, you’ll never be able to eliminate all the variables and, because of that, you’ll never be able to eliminate all of the high and low blood sugars. Once I realized that there was no way to be “perfect,” it let me stop feeling like that was something I had to strive towards. I could live my life the way I wanted to live it without letting type 1 diabetes dictate what I did or didn’t do. 

—Craig Stubing

Impetus and Understanding

I can honestly say that physical exercise is the best control I have for maintaining my health. In tracking my blood sugars on a daily basis, when I am not taking care of my health because I am too busy to commit to the required exercise, my blood sugars are high and not in control. When I have followed a regular, moderate exercise program that features cardiovascular activity and other strengthening elements, my blood sugars are much more in control, I feel better, and I do not exhibit the symptoms of high blood sugars–fatigue, irritability, thirst. The effect of regular exercise gives me the impetus, understanding, and means to stop the daily decline and compromise of myself as a result of physical inactivity.

—Jay Stein, 68, is an attorney who regularly “manages” the Los Angeles Dodgers from his offices and home.

  • Last Reviewed: May 7, 2013
  • Last Edited: November 20, 2018

Articles from Diabetes Forecast® magazine:

Diabetes Forecast