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Diabetes & Exercise

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Why Does My Blood Sugar Rise After Exercising?

Carrie Mccorkindale, MPH, RD, CDE
March 30, 2020

Exercise can cause stress hormones, like adrenaline and cortisol to raise the glucose. These hormones are resistant to insulin, and exercise often stimulates the liver to release more of them which in turn causes the blood sugar to rise.

Just as each person who has diabetes is different, exercise can affect each person’s blood sugars differently. If the intensity and duration of exercise is for a long period of time, the blood sugar often spikes but will return to normal in an hour or two.

Exercise is a good way that works in your favor by helping you sleep better and can often offer glucose control for 24 hours afterwards.

Wondering how to blend in exercise and eating healthy to get your glucose looking just right? Here are some guidelines for exercise based on your blood sugar level:


If Blood Sugar Is:  Recommendation  Treatment
Less than 100 mg/dl This level may be too low to safely exercise Eat 15-30 grams of carbohydrate before exercising like ½ cup of juice, fruit, crackers, or 4 glucose tablets.
Between 100-250 mg/dl  

This is safe to exercise

Greater than 250 mg/dl This may be too high Check your urine for ketones. Having ketones means that your body doesn’t have enough insulin to take the sugar in your body to your cells to provide energy.

For some individuals who plan to increase their exercise intensity or who meet certain higher-risk criteria may benefit from referral to a health care provider for a checkup and possible exercise stress test before starting such activities.