During exercise: Watch for symptoms of low blood sugar

During exercise, low blood sugar is sometimes a concern. If you're planning a long workout, check your blood sugar every 30 minutes — especially if you're trying a new activity or increasing the intensity or duration of your workout.

This may be difficult if you're participating in outdoor activities or sports. However, this precaution is necessary until you know how your blood sugar responds to changes in your exercise habits.

Stop exercising if:

  • Your blood sugar is 70 mg/dL (3.9 mmol/L) or lower
  • You feel shaky, weak or confused

Eat or drink something to raise your blood sugar level, such as:

  • Three or four glucose tablets
  • 1/2 cup (118 milliliters) of fruit juice
  • 1/2 cup (118 milliliters) of regular (not diet) soda
  • Five or six pieces of hard candy

Recheck your blood sugar 15 minutes later. If it's still too low, have another serving and test again 15 minutes later. Repeat as needed until your blood sugar reaches at least 70 mg/dL (3.9 mmol/L). If you haven't finished your workout, continue once your blood sugar returns to a safe range.

After exercise: Check your blood sugar again

Check your blood sugar right away after exercise and again several times during the next few hours. Exercise draws on reserve sugar stored in your muscles and liver. As your body rebuilds these stores, it takes sugar from your blood. The more strenuous your workout, the longer your blood sugar will be affected. Low blood sugar is possible even several hours after exercise.

If you do have low blood sugar after exercise, eat a small carbohydrate-containing snack, such as fruit or crackers, or drink a small glass of fruit juice.

Exercise can be beneficial to your health in many ways, but if you have diabetes, testing your blood sugar before, during and after exercise may be just as important as the exercise itself.

Feb. 22, 2014 See more In-depth