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Healtheuniversity > English > Diabetes College > Get Active > Safe Exercise > Exercise and Low Blood Sugar

Exercise and Low Blood Sugar

Know your risk of getting low blood sugar when you exercise and be prepared to take action.

  • Take extra care when doing exercise if you are on insulin or a Secretagogue medicine. These medicines increase your risk of low blood sugar, especially after exercise.
  • Be prepared for low blood sugar and have fast acting carbohydrates close by to eat.

Some diabetes medicines can cause low blood sugar (hypoglycemia). 

Take extra care if you are on:

  • Insulin
  • Glyburide (Diabeta or Glynase)
  • Glipizide (Glucotrol)
  • Gliclazide (Diamicron)
  • Glimepiride (Amaryl)
  • Repaglinide (Gluconorm)

These diabetes medicines increase your risk of low blood sugar, especially after exercise.

Remember that low blood sugar (hypoglycemia) is a blood sugar reading of less than 4 mmol/L or you feel the sign of low blood sugar. 

  • Notice patterns in how your body responds to exercise. These patterns will help you predict low blood sugar.

Be prepared and have fast acting carbohydrates close by to eat (such as sugar tablets, juice or pop). Fast acting carbohydrates raise your blood sugar quickly.

Take Action

If you are taking a diabetes medicine that can cause low blood sugar (hypoglycemia)

  1. Check your blood sugar before exercise. If your blood sugar is less than 5 mmol/L, eat a snack before you exercise. This will help you avoid low blood sugar during or after exercise. This snack should have a slower acting carbohydrate and protein like reduced-fat cheese and crackers or an apple. Slower acting carbohydrates raise your blood sugar slowly over a period of time.
    • To avoid needing to snack before exercise, try to plan your exercise when your blood sugar is naturally higher. Plan your exercise about 2 hours after a meal (when your food is digested) or before taking your insulin.
  2. Check your blood sugar after exercise. If your blood sugar is between 4 to 5 mmol/L after exercise, eat your usual meal. Have a snack if your meal is more than 1 hour away. This snack should have a slower acting carbohydrate and protein like a slice of wholegrain bread with reduced fat cheese. Slower acting carbohydrates raise your blood sugar slowly over a period of time. Your blood sugar will keep dropping hours after exercise. The snack prevents low blood sugar after your exercise.
  3. Check your blood sugar before you drive. Your blood sugar must be above 5 mmol/L if you drive after exercise. This blood sugar level will prevent low blood sugar while you are driving. Recheck your blood sugar on long drives. Carry a fast acting carbohydrate and your glucometer with you in the car in case you need them.
  4. Your blood sugar levels will change after you start a new exercise program. You may have low blood sugar more often after you start. Talk to your healthcare team about your diabetes medicines if this happens. You will likely need the amount of diabetes medicine you take changed.

If you are taking insulin

Avoid injecting insulin in an exercising muscle. For example, do not inject into your thigh if you are walking or cycling. Instead, inject insulin into sites on your belly. 

If you have had previous episodes of low blood sugar

​Take extra care. Check your blood sugar before, during and after you do exercise. Your blood sugar tells you how your body reacts to exercise. Have proper nutrition and timing of medicines to avoid low blood sugar.

​If you cannot tell when you have low blood sugar

​Take extra care. Check your blood sugar before, during and after you do exercise. Your blood sugar tells you how your body reacts to exercise. Have proper nutrition and timing of medicines to avoid low blood sugar.

If you are not taking insulin or a medicine from the Secretagogue class of medicines

Low blood sugar is rare. Still check your blood sugar before and after a few exercise sessions to know how your body reacts.

Last Reviewed: 10/16/2016