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Why is My Blood Sugar Elevated after I Exercise?

Updated: Aug 21, 2021


Diabetes is a difficult disease to manage. Many individuals find it very frustrating when their blood sugar fluctuates up and down. Most health professionals confirm that physical activity is a major component of diabetes self-management. But many individuals with diabetes complain that sometimes when they exercise their blood sugar goes up instead of down.

Benefits of Exercise

Exercise helps with weight loss and weight maintenance especially for those with type 2 diabetes. It helps in the lowering of cardiovascular disease risk factors such as heart disease, stroke, and high blood pressure. It helps to improve sleep, improve mood, decrease stress, and increases energy. Exercise helps with lowering of total cholesterol, bad cholesterol, triglyceride and raises good cholesterol. Additionally, exercise increases lean muscle mass and strength. It also prevents injury. In addition, it helps to prevent or delay the onset of type 2 diabetes

Exercise and Blood Glucose

It is a proven fact that exercise lower blood sugar and helps with lowering the amount of medication that an individual with diabetes might need. However, high-intensity exercise such as sprinting, weight lifting, playing hockey, and basketball especially competitively can raise blood sugar. This does not mean that high intensity should be avoided but it is best to check blood sugar before and during physical activity to monitor blood sugar.

Another factor that affects high blood sugar after exercise might be from overconsumption of carbohydrates (carbs) prior to exercise. While it is recommended to consume carbs before exercise it is best practice to check blood glucose before and consume carbs based on the blood glucose level. To figure out how much carbs you will need, match the duration and intensity of exercise to the gram of carbs you will need base on your blood sugar level in the table below 1.

Finally, for those with type 1 and type 2 diabetes who are taking insulin, reducing your dose before exercise usually helps to prevent hypoglycemia but missing dose or under dosing can cause hyperglycemia. It is important to determine for yourself how much insulin you will need by checking your blood sugar before an exercise session.

Carbs intake (grams)

Exercise Exercise Blood Sugar Blood Sugar Blood Sugar Blood Sugar

Duration Intensity <100 mg/dl 100-150 mg/dl 200 mg/dl >200 mg/dl

30 minutes Low 5-10 0-10 none none

Mod. 10-25 10-20 5-15 0-10

High 15-35 15-30 10-25 5-20

60 minutes Low 10-15 10-15 5-10 0-5

Mod. 20-50 15-40 10-30 5-15

High 30-45 25-40 20-35 15-30

Bottom Line

“Exercise is medicine” for all! It is beneficial for individuals with diabetes because it helps to lower blood sugar and reduce the risk of diabetes complications. However, It is best to check blood sugar before and after exercise to learn how the activity affects your blood sugar level. After you exercise, if your blood sugar is less than 100mg/dl follow your regular meal plan. If it is not the time for your next meal you may need a snack. If you feel any symptoms of hypoglycemia such as excessive sweating, anxiety, shakiness, confusion, and/or low energy, stop exercising and check your blood sugar. Talk with your doctor before you start a new exercise routine, especially if it is more rigorous than what you usually do.

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