My CGM Spiked and I Hadn’t Eaten a Thing: Here’s Why

Dr Victoria Manning
1 day ago
3 min read

As many of you know, I’ve been wearing a Continuous Glucose Monitor (CGM) as part of our new MAP Health Longevity testing. It’s been fascinating to see in real-time how my body responds to food, exercise, and sleep. But the most shocking discovery? My blood sugar spiked to its highest point all week, and I hadn’t eaten a single thing.

What happened? Life happened. It was a day of back-to-back patients, culminating in a flat tyre on the way home. As I waited for the AA, frustrated and late, my CGM was telling a story that had nothing to do with my diet.

My glucose had skyrocketed. This is a perfect, real-world example of something I discuss constantly with my patients and in my book: stress, not just sugar, has a powerful impact on your metabolic health and the way you age.

The Science: Why Stress Spikes Your Blood Sugar

It seems counterintuitive, right? How can your blood sugar go up if you haven’t eaten? The answer lies in our ancient survival wiring and a hormone called cortisol.

When your body perceives a threat—whether it’s a genuine danger or a modern stressor like a flat tyre—it triggers the “fight-or-flight” response. This is a primal mechanism designed to give you a burst of energy to escape danger. Here’s what happens:

Cortisol Surges: Your adrenal glands release cortisol, the body’s main stress hormone.

Liver Releases Sugar: Cortisol signals your liver to dump its stored glucose (a sugar called glycogen) into your bloodstream . Your body thinks you need instant fuel to run or fight.

Insulin is Blocked: At the same time, cortisol can make your body temporarily resistant to insulin, the hormone that normally helps clear sugar from your blood .

The result is a rapid increase in blood glucose, providing that emergency energy boost. The problem is, our bodies haven’t evolved to distinguish between the stress of a predator and the stress of a packed schedule. The physiological response is the same.

Stressor	Body's Interpretation	Hormonal Response	Result
Ancient Threat (e.g., Tiger)	"I need to run for my life!"	Cortisol + Adrenaline Surge	Glucose released for immediate energy to escape.
Modern Threat (e.g., Flat Tyre)	"This is a disaster!"	Cortisol + Adrenaline Surge	Glucose released, but with no physical outlet, it stays elevated in the blood.

The Spider in the Room: My Analogy for Stress

I often use the “spider in the room” analogy with my patients. Imagine there’s a spider in the corner. Even if it’s not moving, just knowing it’s there keeps you on edge. Your nervous system is on high alert. You can’t fully relax. That’s chronic stress.

That constant, low-grade stress keeps cortisol levels simmering, leading to persistently elevated glucose. Over time, this can contribute to insulin resistance, weight gain (especially around the middle), and, you guessed it, inflammaging.

What My CGM Taught Me

Seeing that spike on my CGM was a powerful reminder that managing our health goes far beyond diet. We can eat a perfect diet, but if we don’t manage our stress, we are missing a huge piece of the longevity puzzle.

This is exactly why our new MAP Health Longevity testing is so revolutionary. By combining CGM with epigenetic and inflammatory biomarker analysis, we can see the full picture. We can identify not just what is happening in your body, but why.

Are you ready to stop guessing and start understanding your own unique biology? Join us at our free Longevity Event on March 4th to learn more.