The Blood Sugar Dip Before the Spike
The Blood Sugar Dip Before the Spike Ever finish a workout only to spike like crazy an hour later? Here’s why it happens, and how to plan for it. Today, We’re Covering: The science behind anaerobic exercise and BG spikes My CrossFit spike...
The episode, word for word
So... you finally made it to the gym.
You crushed the WOD, or that strength circuit, or maybe just tried something new that had you breathing fire.
You check your CGM, and it looks awesome.
Maybe even too awesome.
But then?
An hour later... your blood sugar spikes like you just ate pancakes in the parking lot.
I know this one too well.
Hey, I'm Neil, and this is Your Best T1D Year.
Today we're talking about one of the most annoying things that can happen after a high-intensity workout with type 1 diabetes: the post-exercise spike.
It's not random. It's not your fault. And it's way more common than most of us were ever told.
Let's get into it.
Here's what's going on behind the scenes:
When you do something intense, CrossFit, HIIT, heavy strength training, your body sees that effort as a stressor.
And what does your body do in response to stress?
It releases adrenaline and cortisol, which tells your liver to dump stored glucose into your bloodstream.
(Thanks for the panic carbs, liver.)
This spike is often delayed, it can hit 30 minutes to 2 hours after the workout.
It's not because you "did it wrong."
It's because your body's trying to protect you. It's just... a little confused about what "danger" means.
High-intensity workouts cause spikes because they're more anaerobic and stress-heavy, so you see a surge of stress hormones followed by a delayed glucose release.
Yup. That's what I was seeing every time I tried CrossFit. This is actually why I quit CrossFit style workouts years ago. I felt so defeated.
I'd finish the workout, feel fine, and then two hours later be staring at a 320 like, How?!
Meanwhile, I hadn't eaten a thing.
So what can you do?
You might try:
A small correction bolus right after your workout
A temp basal increase if you're on a pump
Pre-bolusing for the spike if you know it's coming
Or simply tracking the pattern so you can catch it sooner next time
But this only works if you're watching without shame.
The goal here is awareness.
That spike? It's data. It's a pattern you can work with.
You're learning what works for your body.
This week's experiment is simple:
Notice what your blood sugar does after your next intense workout.
Whether it's a bike ride, CrossFit, lifting, or sprinting after your kid.
Then write it down.
Or send it to a friend.
Or tag me in your log if you're feeling bold.
This is how you start building a T1D game plan that works.
And speaking of building a game plan, next week, we've got a special guest joining us:
Ginger Vieira is coming on the show for a long-form episode on July 14.
She's a powerhouse in the T1D and fitness space, and you're gonna want to hear this one.
By the way, if you've ever felt like you're managing all this alone?
You're not.
[ ](https://bluecirclehealth.org) is offering free virtual care for adults with T1D.
No insurance drama. No fine print.
Just real support, CGMs, insulin, mental health, and coaching that actually helps.
They get it.
New episodes drop every Monday, Wednesday, and Friday.
Subscribe. Share. And let me know what you're learning.
And hey, if post-workout spikes are driving you wild?
Welcome to the club. You're not broken. Nobody remembers easy.
You're not doing a bad job - you're doing a difficult job. There's a difference.
Let's keep going.
64 - July 11
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.