Impact of exercise on blood glucose levels


Let us understand the step-by-step process of what can happen to blood glucose levels before we exercise, during the exercise and after the exercise along with the regulatory and precautionary measures to be taken in each case.

Before you exercise

Why is it important to check your blood glucose levels before you exercise?

If you are newly adopting an exercise regimen and have diabetes, it is crucial that you check your blood glucose levels because taking insulin or blood glucose-regulating medication can cause hypoglycemia or severely low blood glucose levels during an intense workout especially if you are not used to it.

Hence, it is important that you check your blood glucose levels with a reliable glucometer to avoid hypoglycemia which can cause organ failure and even death in extreme cases.

Levels of blood glucose and what they indicate:

Blood glucose levelsIndication on exercising
<100 mg/dLThis level of blood sugar is very low to exercise thus it is important to consume a food rich in carbohydrates that will normalise and maintain the required blood glucose levels
100-250 mg/dLSafe blood glucose levels to exercise
>/= 250 mg/dLThis could be a very high level of blood glucose to be able to exercise, it is important to get yourself checked for ketoacidosis which is a deadly condition and requires medical attention leading to death if it goes untreated

During exercise:

When we exercise, our blood glucose levels drop and may lead to hypoglycemia in case of a high-intensity workout.

More importantly, for a diabetic patient, it is recommended to check the blood glucose levels every 30 minutes during exercise.

In case the blood glucose drops to alarmingly low levels, it is important to not work out until the blood sugar levels normalise.

Do not continue exercising if 

  • You are constantly sweating
  • You are trembling 
  • Feeling nauseous or dizzy 
  • Experience a sudden pain in the chest or congestion
  • Have a history of hypoglycemia
  • You are diabetic and have not monitoring your blood glucose levels
  • If your blood glucose levels drop below 70 mg/dL during the exercise

What to do if you experience low blood sugar during your exercise?

Consume a carbohydrate-rich food until your blood sugar levels normalise and even after normalising go slow, don’t burden your body with an intense workout immediately after your glucose levels have gone for a toss.

If you continue experiencing hypoglycemia or any of the above signs, exercise only under medical supervision.

If you suffer from any disorder that causes impairment in blood glucose levels, do not start exercising until you have consulted a doctor.


Your blood glucose levels may slightly reduce as compared to those that were at the beginning of the exercise because your body extracts energy from the glucose in the blood and glycogen in the liver and muscle in that order just for your body to compensate for the energy demand during the exercise.

Fluctuations in blood glucose may continue for hours post the workout depending on the duration and intensity of the workout. Hence, consume food that releases glucose slowly into the blood, for example, protein-rich food or a shake, a healthy carb-rich granola or quinoa. Such foods are difficult to break down so they don’t cause a sudden rise of blood glucose post a workout that reduces blood glucose levels which may cause shock in our body.

Points to remember if you are working out as a diabetic:

  1. Always monitor your blood glucose levels before, during and after a workout.
  2. Always carry a certified glucometer with you.
  3. Carry a healthy snack that you can consume in case your blood sugar drops during the workout.
  4. If you have high blood glucose levels prior to exercise, make sure you check yourself for ketoacidosis.
  5. If you are planning to start working out, make sure you consult your diabetes specialist so that your insulin medication is adjusted accordingly. Because if you continue working out intensely with the same dose of insulin, due to the nature of the medicine, your blood glucose may drop drastically causing extreme hypoglycemia which is fatal.

Remember, good exercise can not only help in maintaining your blood sugar levels at normal but also help in reversing type 2 diabetes if it is effective and practised consistently. On the other hand, an exercise that is not supervised can even cause heart attacks leading to unimaginable consequences and health complications.

Exercise can reduce blood sugar.
Exercise can reduce blood sugar.
Impact of exercise on blood glucose level

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