You’re sitting at dinner, and the person across from you has a small white circle stuck to the back of their arm. Ten years ago, you’d assume they had Type 1 diabetes. Today? They might just be a software engineer or a CrossFit enthusiast trying to see what that sourdough bread actually does to their blood sugar.
This shift—this "democratization" of medical hardware—is largely thanks to Dr. Casey Means.
Casey Means isn't just a doctor; she’s a Stanford-trained surgeon who walked away from the operating room because she realized she was essentially "mopping up the floor while the faucet was still running." She saw patients with chronic inflammation and sinus issues that wouldn't quit, and she realized the root wasn't in the nose or throat. It was in the cells. Specifically, it was how those cells were processing energy.
This realization led her to co-found Levels and champion the Casey Means continuous glucose monitor (CGM) philosophy. She’s essentially betting that if we can see our internal data in real-time, we’ll stop making the choices that are slowly making us sick.
Why a Surgeon Cares About Your Blood Sugar
It sounds a bit dramatic, right? Why would an ENT surgeon quit her lucrative career to talk about glucose?
Honestly, it’s because of the statistics. We’re looking at a world where 93% of American adults are metabolically unhealthy. That is a staggering number. It means almost everyone you know has some level of "metabolic dysfunction."
Dr. Means argues that things like fatigue, brain fog, acne, and even infertility are often just "smoke" from the fire of metabolic instability. When you use a Casey Means continuous glucose monitor approach, you aren't looking for a diabetes diagnosis. You’re looking for the "spikes" and "crashes" that dictate your mood and energy for the day.
Standard medicine usually waits until your fasting glucose hits 100 mg/dL (prediabetes) or 126 mg/dL (diabetes) to say something is wrong. Means thinks that’s way too late. She advocates for a tighter "optimal" range—ideally keeping your fasting glucose between 70 and 85 mg/dL.
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The Biofeedback Loop: Your Body Doesn't Lie
The "magic" of the CGM is the closed-loop feedback.
Usually, if you eat a "healthy" oatmeal bowl and feel sleepy an hour later, you blame the weather or a bad night's sleep. With a CGM, you look at your phone and see a giant mountain peak on the graph. You realize that "healthy" oatmeal sent your sugar to 160 mg/dL, and the subsequent "crash" is why you’re currently reaching for a second cup of coffee.
It’s Individual—Kinda Like a Fingerprint
One of the most eye-opening things Dr. Means talks about is the Weizmann Institute study. It basically proved that two people can eat the exact same banana, and one person’s blood sugar will barely move while the other’s sky-rockets.
You can't get that info from a nutrition label.
I’ve seen people find out that grapes spike them worse than a cookie. Or that white rice is fine for them, but brown rice causes a multi-hour glucose elevation. This is the "n=1" experimentation that Means promotes. It’s about moving away from "one size fits all" diets and moving toward "what does my body do with this sweet potato?"
The "Good Energy" Framework
In her book Good Energy, Means connects the dots between the CGM data and mitochondrial health. Think of your mitochondria as the tiny power plants in your cells. When you flood them with too much glucose too often (those big spikes), they basically get overwhelmed and start producing "bad energy."
This leads to:
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- Oxidative stress (cellular rusting)
- Systemic inflammation
- Insulin resistance
By using a Casey Means continuous glucose monitor strategy, the goal is to keep the "hills" small. You want rolling hills, not the Swiss Alps.
How to Blunt the Spike
You don't necessarily have to give up carbs forever. Dr. Means talks a lot about "food sequencing" and "pairing."
- Fiber first: Eat your greens before the starch.
- Add "clothing": Never eat a "naked carb." Put some fat or protein on that apple (like almond butter).
- Vinegar trick: A tablespoon of apple cider vinegar in water before a meal can significantly blunt the glucose response.
- The Post-Meal Walk: Muscle contraction is a glucose sponge. Even a 10-minute walk after lunch can "soak up" the sugar before it turns into a massive spike.
Is It Just for "Healthy" People?
There’s a bit of a debate here. Some traditional doctors think giving CGMs to non-diabetics is overkill. They worry it leads to "orthorexia" or unnecessary anxiety over normal fluctuations.
Dr. Means counters this by pointing out that we track our steps, our sleep, and our heart rate—so why wouldn't we track the most fundamental fuel source in our bodies?
The reality is that "normal" ranges in the US are based on a population that is largely unhealthy. If you want to be "optimal," you have to look beyond what is merely "normal."
Putting the Data to Work
If you actually decide to wear a Casey Means continuous glucose monitor (likely through a platform like Levels), the first week is usually just a "discovery" phase. You eat normally. You see the damage.
The second week is where the "tinkering" starts.
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You might find that you can handle sourdough bread if you have it with avocado and eggs, but if you have it as toast with jam, you’re a mess. This isn't about restriction; it’s about informed choice.
Beyond the Food
It’s not just about what you chew. The CGM data often reveals two other big culprits:
- Stress: You can be fasted and sitting at your desk, but if you get a stressful email, your liver will dump glucose into your bloodstream to help you "fight the lion." Seeing a spike while sitting still is a huge wake-up call for stress management.
- Poor Sleep: One night of bad sleep can make you as insulin resistant as a prediabetic the next morning. Your CGM will show higher baselines and bigger spikes after meals when you're exhausted.
The Big Picture
The Casey Means continuous glucose monitor movement is really about personal agency. It’s moving the "source of truth" from a doctor’s office visit once a year to your own pocket, 24/7.
When you understand that your 3 p.m. irritability is actually a glucose crash, or that your "healthy" green juice is actually 40 grams of liquid sugar, you can't "un-see" it.
Actionable Next Steps
If you're looking to apply these principles without necessarily buying a sensor tomorrow, here is how you start:
- Check your labs: Look at your Fasting Glucose and HbA1c. If your fasting glucose is consistently above 90, you might want to look closer at your metabolic health.
- Order your food: Try the "fiber, then protein, then starch" order for three days. Notice if your energy levels are more stable in the afternoon.
- Walk after your biggest meal: It’s the simplest "hack" in the book. 15 minutes of movement makes a massive difference in how your body handles that glucose.
- Prioritize "Good Energy" markers: Aim for a triglyceride-to-HDL ratio of less than 1.5, which Dr. Means often cites as a better marker of insulin sensitivity than glucose alone.
Metabolic health isn't a destination; it's a "fitness" level you maintain. Using tools to see the invisible just makes the training a whole lot easier.