7 Reasons Dr. Casey Means believes in CGM

In this excerpt from her new book, Good Energy, Levels co-founder Dr. Casey Means gives 7 reasons CGM is a crucial tool for improving metabolic health.


I believe CGM is the most powerful technology for generating the data and awareness to rectify our Bad Energy crisis in the Western world. A CGM is a biosensor that can alert us to early dysfunction, coach us on how to eat and live in a way that promotes Good Energy in our unique bodies, and promote accountability. My belief in the potential of this technology to reduce global metabolic suffering is why I cofounded Levels, which enables access to CGMs and software to understand and interpret the data.

A CGM is a small plastic disc worn on the arm that automatically tests your blood sugar roughly every ten minutes, twenty-four hours a day. And it sends that information to your smartphone. As opposed to just having a single yearly snapshot of glucose—like a fasting glucose test in a lab—a continuous glucose monitor tells you exactly how your body is responding in real time to every action you take, like eating breakfast, exercising, walking, getting a poor night’s sleep, or experiencing stress. These factors can change glucose levels almost immediately. In working to prevent the metabolic issues that 93.2 percent of people in the United States are facing, rather than just one data point, I’d rather have up to 35,040 painless data points per year to drive personalized decision-making.

Wearing a CGM as part of a journey to understand and optimize health provides seven main benefits.

1. Improve Glycemic Variability

Glucose levels should be generally stable and rise only slightly after meals. High variability in glucose levels can damage tissues and lead to heart disease, diabetes, and metabolic dysfunction. A study from Stanford found that even among people considered healthy by standard glucose ranges, 25 percent of them showed severe glucose variability based on CGM data, and the percentage of time spent in severe variability patterns correlated with worse metabolic markers.

2. Reduce Cravings and Anxiety

High glucose spikes lead to bigger glucose crashes, which can lead to cravings, fatigue, and anxiety. Recent CGM research showed that glucose dips—or reactive hypoglycemia—after meals can predict how hungry people would be later in the day, how soon they would eat again, and how much they would eat at the next meal. And bigger crashes led to eating more calories in a twenty-four-hour period. CGMs can teach you how to avoid reactive hypoglycemia by keeping blood sugar more stable and avoiding sharp spikes.

3. Learn Your Reaction to Individual Foods and Meals

Different individuals respond differently to the same food (in terms of blood sugar rise), depending on factors such as microbiome composition, sleep, recent meals, and body type. Simply reading carb content or looking at a food’s glycemic index is not sufficient to help you find a diet and lifestyle that allows you to maintain stable glucose. Chronic overnutrition is a key cause of Bad Energy that overwhelms our cells and causes oxidative stress, inflammation, mitochondrial dysfunction, glycation, and insulin resistance. CGMs can be useful in showing you the exact impact of a meal on your blood glucose levels. An extra-large spike after a meal is a clear sign that the meal had too much refined grain or refined sugar and is creating a big stress of food energy for your cells to deal with.

4. Learn to Use Strategies to Stabilize Glucose

Balancing meals with enough fiber, protein, and fat; eating meals earlier in the day and avoiding late-night meals; walking after meals; and not eating while stressed are some strategies that can help keep glucose stable. A CGM can help you experiment with different stabilizing strategies.

5. Train the Body to Be Metabolically Flexible

Burning fat produces ketones, which have health benefits. But if the body is constantly getting fed glucose—the body’s preferential source of food energy to convert to ATP—it’s not going to prioritize burning fat. By learning to keep blood sugar levels low and healthy through diet and lifestyle, we increase the opportunity for our body to tap into fat stores for energy, which improves metabolic flexibility (an indicator of better health).

6. Catch Metabolic Dysfunction Earlier

Fasting glucose can remain low despite increasing insulin resistance as the body pumps out excess insulin to overcompensate for an insulin block. By viewing a continuous glucose curve on CGM, we can see more subtle clues indicating early dysfunction, like how high our post-meal glucose levels are, which is an early sign of dysfunction.

7. Motivate Behavior Change

Seeing real-time glucose data and the impact of meals and activities on glucose levels can motivate behavior change and encourage healthier choices, which can lead to better overall health outcomes.

Printed with permission from: Good Energy: The Surprising Connection Between Metabolism and Limitless Health by Dr. Casey Means with Calley Means, published by Avery, an imprint of Penguin Publishing Group, a division of Penguin Random House, LLC. Copyright © 2024.

Available May 14, 2024. Pre-order your copy here!