The Best Ways to Prevent Lows (or Highs!) During Exercise

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The Best Ways to Prevent Lows (or Highs!) During Exercise

Question: What's the best way to prevent lows (or highs!) during exercise? 

Answer: Exercise can be a very effective way to help maintain good blood glucose control, but special attention needs to be made in those with diabetes to ensure blood glucose levels don’t drop too low, or in some cases, become too high.

Exercising causes our muscles to use up glucose, which comes from eating carbohydrate-rich foods. This means that not eating adequate carbohydrates before exercise could potentially cause hypoglycemia, or low blood glucose (less than 70 mg/dL), which can be dangerous.

Exercise also improves insulin sensitivity, so blood glucose will often naturally be lower after engaging in physical activity, even if the exact same meal was eaten as on a day when exercise did not occur. On the other hand, because glucose needs the hormone insulin to enter our cells and supply the muscles with energy, insufficient insulin can actually cause the blood glucose reading to be especially high after exercise until insulin comes and “unlocks the door” to allow it to enter the muscles.

Since regular physical activity is one of the single best things we can do to improve both our blood sugar control and overall health, here are a few tips to make sure you are safe during your workouts.

Tips to maintain good blood sugar control before, during, and after exercise:

  • Avoid exercise if blood sugars are over 400 or less than 100
  • Exercise 1 to 1 ½ hours after eating a small to mid-size meal or snack
  • If using insulin, avoid exercising at the peak time of insulin action
  • If exercising for more than an hour or at extremely high intensities, consume an easily digested carbohydrate source like energy gels or a sports drink about halfway through the activity
  • Always have a carbohydrate snack (fruit, yogurt, whole wheat bread or crackers, etc) on hand to consume within 15 minutes after completion of the activity and plan to eat a full meal within 1-2 hours of completion
  • Drink plenty of fluids before, during, and after exercise

Practicing these habits can make it easier and safer to incorporate regular physical activity into your lifestyle which is a key component of proper diabetes self-management.