What Happens to the Body During Exercise? A Guide for Diabetics

Exercise and Diabetes

Managing your diabetes can feel like a minefield at times. There are many factors that can have an impact on your blood glucose levels and sometimes even when you do everything right it can unexpectedly kick you in the behind. However, we are believers in knowledge being power when it comes to managing your condition. The more that you know about how your body reacts to different scenarios the better you can manage your blood sugars.

Of course, trial and error through time gives you a good level of understanding and nobody will understand your body better than yourself. However, if an increased understanding can improve your management by even the smallest margin then the overall positive impact to your life can be huge.

Below we have produced a brief description of how the body uses energy during exercise, and how this differs to a person without diabetes. Understanding what is going on inside your body will help you to make more informed decisions. Please note that it is important to speak with your medical advisor before making changes to your treatment plan. 

The body’s reaction to exercise 

When taking part in aerobic exercise (which is classed as repeated movements of large muscle groups for at least 10 minutes at a time, e.g. walking, jogging or swimming), the body is fuelled mostly by energy that is stored in the muscles.
Shortly after starting exercise this changes, and broken down sugar and fat in the body become the main source of fuel.
In individuals without diabetes, the body reduces the release of insulin during exercise whilst also releasing more glucagon. As a result of this, blood glucose levels can remain relatively stable during exercise for several hours without food intake.
For individuals with type 1 diabetes things are different, a non-functioning pancreas leads to the requirement for insulin through injection or infusion.
Insulin levels are regulated solely by the individual and therefore are heavily influenced by the timing and quantity of insulin taken by the individual before exercise.
Insulin levels are often higher than they would be in the absence of diabetes, which can lower glucose production and increase glucose storage in the body. As a result of this, blood glucose levels often decrease dramatically during aerobic exercise for individuals with type 1 diabetes (unless carbohydrates are consumed before, during and after exercise).
As the intensity of exercise increases (for example sprinting or HIIT workouts), glucose is broken down faster than it can be used by the body. This can lead to glucose production exceeding demand, resulting in an increase in blood glucose concentration.
 High-intensity exercise is also associated with increases in growth hormone and lactate, both of which can serve to spare circulating blood glucose. (Growth hormone can decrease the body’s reliance on circulating glucose, whilst lactate can be used by the liver to create new glucose). Therefore, it makes sense that high-intensity (anaerobic) exercise would be associated with either increases (or weakened declines) in blood glucose levels.
This topic is well discussed, and it has been suggested that the inclusion of high-intensity exercise, such as short sprints or weight training, in exercise sessions involving moderate aerobic exercise may provide a level of protection against hypoglycaemia (without the need of excess carbohydrates).



Aerobic exercise = likely blood glucose will reduce

Anaerobic exercise = likely blood glucose will increase

This is only during exercise and does not include the body’s reaction post exercise.

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