Should You Really Be Using a Continuous Glucose Monitor?

You've probably seen it all over TikTok and Instagram: continuous glucose monitors (CGMs) have become the latest wellness trend. Influencers and quasi-celebrities are wearing these little devices, claiming they help track glucose spikes and keep blood sugar levels in check. But is this really the health game-changer it's made out to be?

To help answer this question, we’re leaning on insights from Dr. Karan Rajan, an NHS surgeon and educator with over 10 million followers on social media. Dr. Karan is known for his evidence-based approach, making complex topics accessible to anyone who may have gotten a C- in chemistry at Muhlenberg College in 2001. 

What Exactly is a CGM?

CGM stands for Continuous Glucose Monitor. It's a little sensor you wear on your skin, and it constantly tracks your glucose levels, which many influencers are claiming can tell you a lot about your health. They say CGMs help you understand how the foods you eat impact your blood sugar and, ultimately, your overall well-being. But Dr. Karan has a different perspective on why these devices may not be the best idea for everyone.

The Problem with Glucose Spikes

Dr. Karan challenges the idea that glucose spikes are something we should always be afraid of. Glucose spikes are a normal response to eating—yes, even healthy foods can cause them! In fact, he did a simple experiment where he compared how his glucose responded to two different foods: an apple and a fried chicken wing. Surprisingly, the apple caused a bigger glucose spike than the fried chicken. But does that mean the apple is worse for you? Of course not. Apples are full of fiber, water, and vitamins, while the chicken wing is high in salt and fat. The point is, glucose spikes alone don't paint the whole picture of what's healthy.

More Than Just Glucose

Dr. Karan makes it clear that focusing on glucose alone ignores the bigger picture of our health. Your blood sugar levels aren't just influenced by what you eat—they can be affected by things like how much sleep you got, your stress levels, exercise, illness, and even your menstrual cycle. Imagine you're a sleep-deprived new parent, stressed out and exhausted. If you put on a CGM, you'd probably see some major glucose spikes after breakfast. But there's no way to tell what exactly caused it—lack of sleep, stress, or the food itself. So why obsess over something you can't really control?

The Danger of Over-Fixation

Another key point Dr. Karan brings up is the danger of focusing too much on a single number—your glucose levels. It’s easy to get fixated and lose sight of the bigger picture. We've all met people who obsessively count calories or steps to the point where it takes the joy out of living. Glucose monitoring could easily lead to the same kind of obsession, especially since one way to flatten those glucose curves is by eating more high-fat foods or cutting out carbs altogether. And while some influencers love to vilify carbs, the truth is, they aren't the enemy. Obsessively avoiding carbs or using CGMs as a way to justify unbalanced diets could lead to unhealthy eating habits or even disordered eating.

Are CGMs Even Accurate?

Here’s another wrinkle: CGMs aren't even that accurate for most people without diabetes. Dr. Karan explains that CGMs measure glucose in the interstitial fluid—the fluid between your cells—which doesn’t always match up perfectly with what's actually in your blood. There's a lag, meaning what you see on the CGM may not be a true reflection of your blood glucose in real time. In studies, CGMs have been shown to be the least accurate way to measure blood glucose compared to other methods like finger pricks or lab tests.

So, Should You Bother with a CGM?

If you're not diabetic or an elite athlete, probably not. Dr. Karan says the whole point of CGMs is to help manage conditions like diabetes, where monitoring glucose is crucial for health. For the average person, though, blood glucose is just one small part of your overall health, and obsessing over it can do more harm than good. Instead of paying hundreds of dollars for a CGM, Dr. Karan suggests focusing on habits we know are good for managing blood sugar: eat more fiber, get enough sleep, go for a walk after meals, and eat a balanced diet. You don’t need a fancy gadget to tell you those are good ideas.

Dr. Karan leaves us with an important reminder: our health is influenced by so many factors, many of which are beyond our control. It’s easy to get drawn into quick fixes and fads, but we need to remember that health isn’t about obsessing over one metric. Blood pressure, body weight, family history, lifestyle habits—all of these matter, too. There’s no evidence that wearing a CGM will make healthy people any healthier. In fact, even one of the major CGM companies acknowledges that occasional glucose spikes can be totally normal and even beneficial for our bodies.

So, if you've been thinking about getting a CGM because of what you saw on TikTok or Instagram, maybe think twice. Instead of focusing on a single number, focus on the bigger picture: eat a balanced diet, get moving, sleep well, and don’t sweat the small stuff. That's the real key to good health.

I’m here to support you on your journey to a healthier, fitter life. As always, I appreciate your feedback and suggestions. Let me know what topics you’d like me to cover in future issues by replying to this email.

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Be well,

Dave

Please note: This newsletter is designed for informational purposes only and should not be taken as professional medical advice. Always consult with a healthcare provider for advice tailored to your health and fitness needs.