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Exercise and Blood Glucose Levels

Exercise and Blood Glucose Levels

Whether you're a casual walker or a more serious exerciser, it's important to see how activity affects your glucose control.

For people with diabetes, being physically active helps insulin work more efficiently and generally lowers blood glucose levels. But exercise has additional—and essential—health benefits:

  • Improves circulation and flexibility
  • Strengthens heart, muscles and bones
  • Lowers blood pressure and cholesterol
  • Reduces heart disease and stroke
  • Helps maintain or lose weight
  • Relieves stress

Ideally, most people should be getting a total of 30 minutes of physical activity a day, at least 5 days a week. Exercise can be a wide range of activities from walking from the furthest stall in the parking lot or dancing, to bodybuilding or alpine climbing. What's important is finding something you like to do that gets your heart rate up.

Monitoring means information

People with diabetes should take extra care before exercising because of a potential drop in blood glucose levels after exercise. It's a good idea to consult your healthcare team before starting an exercise program. That way you'll know how to adjust food and medication with the physical activity, and how to react if your blood glucose is too high or too low before, during or after your workout. One way to get immediate feedback on the impact of physical activity is to monitor your blood glucose. How often you test will depend on:

  • The schedule you've set with your healthcare team
  • Your level of control
  • Your medication (or therapy type)
  • How much your blood glucose fluctuates during the day

Being aware of your blood glucose level can help you and your doctor modify your medication dosage or food plan, or switch you to a physical activity that's more effective for you. Blood glucose testing around exercise can provide information to keep your blood glucose levels in range, and help you feel your best.

Before exercising:

  • Your energy level peaks one to three hours after a meal - exercising during this time can be more effective than other times
  • Discuss what's realistic for you with your doctor, but generally, your blood glucose should be 100 mg/dL or higher to begin or continue exercising
  • If low blood glucose (hypoglycemia) interferes with your exercise routine, eating a snack before you exercise may help. Discuss snacks and medication adjustments with your doctor.
  • If your blood glucose is already high (hyperglycemia) be careful. Physical activity can increase blood glucose levels if they are already on the rise.
  • Set a target range with your doctor, but generally, avoid exercise if glucose levels are above 250 mg/dL

For people with Type 1 diabetes:

  • The American Diabetes Association recommends that if your fasting glucose is above 250 mg/dL and you have ketones in your urine (especially before or during exercise), talk with your doctor about a specific plan of action.

What are some ways you might use monitoring?

Be sure to discuss patterns with your healthcare team and explore opportunities for improving your blood glucose control. For example, if your blood glucose is too low after you exercise in the morning, your doctor might recommend testing before and after your activity until you find a routine that doesn't lower your blood glucose so much. Once you've mastered morning workouts, your doctor may advise you to reduce testing around that activity, and focus on another time of day (or event) you may find challenging.


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