Type 1 diabetes - exercice

Benefits of moving

What are the effects
of exercise?

Health benefits of physical exercise

Regular physical activity brings many benefits to both diabetics and non-diabetics:

  • Improves physical fitness and coordination;
  • Helps control weight;
  • Decreases many risk factors for cardiovascular disease;
  • Provides a sense of well-being and reduces stress;
  • Enhances self-image and self-esteem;
  • Develops certain social skills (cooperation, teamwork, socialization, etc.).
Exercising should not be considered a prescription or a requirement to improve diabetes control. Exercise should be enjoyable for your child and should be encouraged according to his or her tastes and abilities.

How exercise can affect diabetes

Regular physical activity (at least three or four times a week) can have a beneficial effect on blood glucose control. It increases insulin sensitivity thus making it more effective! Regular exercise decreases the hyperglycemic peak after a meal as well as the needs for insulin.

30 minutes of moderate physical activity per day is recommended, EVERY day!

The effects of physical exercise on health, diabetes, glycemic control as well as some tips

Effects of physical exercise on glycemic control

Direct effects on blood glucose levels are noted during physical activity.

Exercised muscles consume more glucose. Blood glucose levels can therefore vary downwards (hypo) during the period exercise or several hours afterwards.

Thus, during exercise, the muscles need energy. They use their stored glycogen, and will then use glucose circulating in the blood. This glucose is produced by the liver (from stored glycogen) or is produced by carbohydrates consumed.

Eventually, after prolonged exercise, blood glucose levels may continue to fall as the body continues to use glucose to replenish its reserves.

Occasionally, exercise may initially cause a rise in blood glucose due to the effect of certain hormones, such as adrenaline. This occurs particularly during intense activity. In the second stage, blood glucose levels start to fall.

Other than the risk of hypoglycemia during or after physical activity—if not compensated by an adequate carbohydrate snack—exercise can worsen hyperglycemia and throw diabetes out of balance when control is poor due to insufficient insulin.

It is therefore important to understand how to adjust the various components of one’s diabetes treatment accordingly, namely insulin and diet.

Even during exercise, a certain amount of insulin is needed: exercise cannot replace insulin!

Precautions to take for exercising safely

It is important to realize that the way exercise affects the body is different for each person. Therefore, it is best to rely on personal experience, frequently measuring blood sugar levels before, during, and after exercise, to fully understand how your child may be reacting.

General Practical Tips

Modifications to insulin doses or diet, or both, are suggested and it is up to you to learn how to adjust these components.

For unplanned exercise, it is often a matter of adding snack supplements and monitoring blood glucose levels (no insulin adjustments). For planned exercise, changes in insulin and/or diet should be considered.

This depends on:

  • the duration of the activity
  • the intensity of the activity
  • the blood glucose level at the onset of the activity
  • the time between the activity and the intake of a meal or a snack

Insulin dose adjustment

In case of predictable physical efforts, there are three possible adjustments to be made:
1 – It is possible to manipulate insulin doses;
2 – It is possible to increase the carbohydrate intake at meal and snack times;
3 – It is possible to manipulate insulin doses and carbohydrate intakes.

For example :

  • If an activity is scheduled for two hours after the dinner meal, it will be possible to reduce the dose of ultra-rapid.
  • If an activity is scheduled for the entire day, such as skiing, it would be possible to manipulate the doses of ultra-rapid and intermediate insulin and, at the same time, increase carbohydrate intake.

To what extent should ultra-rapid insulin be decreased?
The decrease in dose is typically 10 to 20% depending on the intensity of the exercise. Sometimes decreases can be as much as 40–50% of the ultra-rapid dose… it is on a case-by-case basis!


  • Blood glucose levels should be between 7 mmol/L and 10 mmol/L before starting exercise.
  • Exercise is not recommended if blood glucose level is above 17 mmol/L and acetone is present in urine.
  • For any exercise period that is under 20 minutes, there is no need to make dietary or even insulin adjustments.
  • For any physical activity, plan to have an extra snack or to increase the carbohydrate content of your regular snack.
  • During prolonged periods of exercise, plenty of fluids should be drunk to avoid dehydration.

Each diabetic must develop their own method!

Physical activity and diabetes
CHU Ste-Justine, Montreal, Canada – Diabetes Section