Cortisol and Blood Sugar: The T1D Overnight Connection You're Probably Missing
Cortisol isn't trying to ruin your blood sugar. It's trying to help. It has never once, in your entire life, acted with malice. It is a useful, important hormone that is, in the modern world, very confused about what an actual emergency...
The episode, word for word
Your CGM says 115. Flat arrow. No active insulin.
The number is fine. You know the number is fine. You've checked it twice. It's fine.
And you're still awake.
It's 2:48am. The room is dark. The number is fine. Your brain is doing a full systems check anyway, because your brain is not willing to take the number's word for it. Your brain would like to see additional documentation.
This is not you being dramatic. This is not you being bad at sleeping. This has a name.
My name is Neil Greathouse, and this is Your Best T1D Year.
All right. I want to talk today about something that doesn't get discussed in T1D content nearly as often as it should.
Fear of Hypoglycemia. FOH. Which, my brain first read that acronym as "fo'", like, a general sense of "fo real." And I thought, yes. That actually tracks. That's about right.
But for real: Fear of Hypoglycemia is a documented, peer-reviewed, legitimately studied phenomenon in T1D populations. It's not just "being nervous about lows." It's a specific pattern of hypervigilance that persists even when blood sugar is stable. Even when the number on the screen is completely fine. The anxiety is the disruptor, independent of the actual glucose level.
Let me tell you what it looks like in real life, because I think some of you are going to recognize this with alarming accuracy.
You go to bed at a good number. Everything is fine. Your CGM is connected, your alarm thresholds are set, you've done everything right. You fall asleep.
And then, at some point, some part of your brain surfaces. Not because of an alarm. Not because of a low. Just because. And it goes: we should check. And you, in your half-asleep state, go: the CGM said 115. It's fine. And your brain goes: but what if it's not. And you go: I just checked. And your brain goes: that was four minutes ago.
This is Fear of Hypoglycemia. And it happens to T1D people on good nights. On nights where the number is perfect and nothing is wrong and the CGM is accurately reading and there's no reason to be awake.
Here's why it exists, and here's why I want to name it without any judgment attached to it.
T1D requires you to be vigilant. That vigilance has, at some point in your diabetes history, prevented something bad from happening. Your brain learned that paying attention at night matters. That the alarm is sometimes real. That a number can look fine and not be fine. And so your brain, being a brain and doing what brains do, built a monitoring system. Permanently. Even for the nights when nothing is wrong.
Think of it like those nature documentaries where the prey animal is completely at rest but never fully asleep. One eye stays open. One ear stays up. Not because a predator is currently present. Because a predator has been present before. Your brain installed a monitoring system that does not have an off switch for T1D nights.
That monitoring system has saved you. It has also cost you sleep. Both of those things are true.
And here's the part I want to really underline. If you've ever been awake at 2am with a perfect number and still couldn't sleep, you were not being a bad patient. You were not being irrational. You were experiencing something that researchers have formally documented and named. Fear of Hypoglycemia. It is in the literature. It's real. You did not make it up.
Naming something changes how you relate to it. "I'm being irrational" is very different from "I have Fear of Hypoglycemia, which is documented and real, and my brain is doing something I understand even if I can't currently turn it off."
We're going to talk about what to actually do about this in the coming weeks. Today, I just want you to have the name. Because nobody told me this name for a very long time, and I think it would have helped.
Have you ever been awake at 2am with a flat, stable blood sugar and still couldn't sleep? Just acknowledge that it happened.
You don't have to fix it today. You don't have to analyze it. Just: yes, I've experienced this. That acknowledgment is the whole challenge.
To the person who has been lying awake with a perfect number on the screen and a brain that will not accept the evidence.
You're not broken. Your brain built a system to protect you. That system has a bug in it that runs even when there's no active threat. That's not failure. That's a feature that got a little overzealous.
You're not doing a bad job. You're doing a difficult job with a nervous system that's been on alert for years. I see you. I'm proud of you.
Type 1 diabetes is relentless, but managing it doesn't have to be. New episodes every Monday, Wednesday, and Friday. You're not doing a bad job, you're doing a difficult job. Nobody remembers easy.
This is the script as read on the mic, lightly tidied for reading. Education, not medical advice. Talk to your care team before you change anything about your insulin.