EP073: Does Your Continuous Glucose Monitor Lie to You? Here's the Truth
Two people can have the exact same A1C — and live completely different lives.
Has your continuous glucose monitor ever gone off in the middle of the night? The alarm screams "LOW!" You wake up scared. But when you check how you feel... you feel totally fine.
So what's going on? Is your device broken?
Nope. And you're not alone.
Richie and Amber sat down to talk about this exact problem. Here's what they want you to know.
What Does a CGM Actually Measure?
Here's a surprise: your continuous glucose monitor doesn't test your blood at all.
"It's not testing blood. It's testing the fluid around your cells," Amber explains.
Think of it like two rooms in a house connected by a doorway. Your blood sugar changes in one room first. Then, a few minutes later, that change shows up in the room next door — the interstitial fluid. That's the room your CGM is watching.
This tiny delay is completely normal. It doesn't mean your sensor is broken.
What Is MARD? (And Why Should You Care?)
Every CGM has an accuracy score called a MARD (Mean Absolute Relative Difference). Think of it like a batting average for accuracy.
A lower MARD number = a more accurate device
A 20-point difference matters way more when your blood sugar is low than when it's normal
This is one reason your CGM might show a scary low number that doesn't match how you feel.
What Is a "Compression Low"?
Ever slept on your arm and your CGM alarm went off? That might be a compression low.
When you put pressure on the sensor — like rolling over onto it while you sleep — it can temporarily block the fluid flow. The result? A false low reading.
Amber shared a real story from her own clinical work where this exact thing fooled even an experienced diabetes educator!
How to Check If It's a Real Low
Before you panic and treat a low reading, ask yourself:
Do I feel shaky, sweaty, or lightheaded?
Was I just lying on that arm?
Does a finger-stick check match the CGM number?
If you feel fine and just rolled off that arm, it might just be pressure — not a true low.
The Boy Who Cried Wolf: Alarm Fatigue Is Real
Richie asked the question so many people are wondering:"How many false alarms before I just start ignoring it?"
This is called alarm fatigue, and it's a huge reason people quit using their CGM altogether.
We want you to know: you are not lazy or broken for feeling exhausted by constant alarms. This is a real, human response to a device that sometimes cries wolf.
There's no shame here. Just understanding — and better tools to tell real lows from false ones.
Time in Range vs. A1C: What's the Real Story?
Your A1C is like a report card average. But two people can have theexact same A1Cand live completely different lives.
One person might have smooth, steady numbers all day. Another might swing wildly high and low — but average out to the same number.
That's why Time in Range matters. It shows how much of your day you spend in a healthy glucose zone, not just an average.
What Affects Your Glucose Variability?
Meal timing
Stress
Sleep
Activity level
Medication timing
Two people, same A1C, very different day-to-day stories.
Trend Arrows Matter Too
Your CGM doesn't just show a number — it shows a direction. A number combined with an arrow pointing down fast tells a very different story than the same number holding steady.
Learning to read these trends (not just the number) helps you respond calmly instead of reactively.
You're Not Failing — You're Learning a New Skill
If your CGM has ever confused you, scared you, or worn you out — that doesn't mean you're doing diabetes wrong. It means you're learning a brand-new skill with imperfect tools.
Give yourself grace. This stuff is genuinely hard, and no one hands you an instruction manual for real life.
What's Next?
This is Part 1 of our CGM series. Next episode, we're breaking down different CGM brands and diving into insulin delivery systems — so stay tuned!
Ready for your next step? Grab our free Prediabetes and Type 2 Diabetes Remission Roadmap at https://roadmap.thediabetespodcast.com. It's simple, practical, and shame-free — just like this podcast.
Take courage. You can do this, and we can help.
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