Continuous Glucose Monitoring: Using Diabetes Tech for Performance

Up until recently, Continuous Glucose Monitoring (CGM) is something that was only used and discussed in clinical settings, generally within the Type 1 Diabetic population, but suddenly it’s a hot topic and has become the latest “nutrition and fitness trend”.

Is Continuous Glucose Monitoring really something we need to do?

While social media, high-profile personalities, and invested brands would have you believe Continuous Glucose Monitoring is a must (the word INVESTED being pointed here) the simple answer is no.

The human body is a series of chemical reactions that work on feedback loops. In individuals without Diabetes, the body can regulate blood glucose within normal limits by the hormones glucagon and insulin. When we consume carbohydrates, we break this down into glucose and this is then stored in our muscles, liver, and brain as glycogen until the body needs it as an energy source. When glucose levels drop, glucagon will release glucose, and when glucose levels rise, insulin will be released by the pancreas and lower glucose levels. This process is part of homeostasis that occurs in the body. Ironically, it’s the body’s own CGM.

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While the human body likes to keep blood glucose levels within a certain range, this is not an absolute number and hereby becomes the issue with this new craze of CGM.

If you believe the hype, you will think that something terrible will happen if your blood glucose is one point off what is deemed “normal”. However, if you look at clinical data, it is clear that it is normal for blood glucose levels to fluctuate a lot throughout the day. This only becomes problematic if your blood glucose remains chronically elevated, which may be a result of insulin resistance. But again, despite the noise, this is not something that tends to affect everyone. It is associated with Type 2 diabetes and is a result of a sedentary lifestyle and individuals holding more adipose around their middle. It is a condition that can be reversed by improved lifestyle behaviors. In contrast, Type 1 Diabetics have a lifelong condition. Their pancreas doesn’t produce insulin as a result of an autoimmune condition which is usually detectable at a young age and these individuals need to be given insulin extrinsically, and in this situation, monitoring glucose is advantageous.

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In amongst all the scaremongering, another key consideration that is often overlooked by the health influencers promoting this so-called “health tech”, is that it's not just food that causes glucose fluctuations. We know that stress, illness, menstrual cycle, dehydration, and movement all contribute. Indeed, a number of case studies have shown that even when individuals eat the same food daily for a week, their blood glucose fluctuates significantly. As food is controlled here, it demonstrates how blood glucose is not just as simple as what we eat.

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So, what happens when we exercise?

When we exercise, blood glucose does rise from 5 mmol to 10 mmol - this is to ensure that glucose can be transported to the working muscles. However, if you were monitoring, you would also see that within a few minutes, blood glucose will also drop as a direct action of exercise. This is why type 1 diabetics have to be mindful when administering their insulin and timing of nutrition when exercising. They have to try and mimic the intricate process and control what goes on naturally within the body

Thus, in reality, the only real outcome of succumbing to the trend and using a CGM is that it creates anxiety and obsessive behaviors associated with carbohydrate consumption. As stated previously, some individuals may develop insulin resistance, but this is rarely those of us who are active and follow general healthy guidelines around eating.

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Remember glucose is the preferred currency of the body, especially the brain. And yes, while it’s best to consume complex carbs that can be broken down into glucose, in certain situations like before and during endurance and high-intensity exercise, easily digestible options are preferable to support performance and recovery.

The final word on this topic – ditch the CGM and instead trust your body and its intrinsic monitoring tool.