Overnight Crashes After (Some) Exercise

Recently found this community and decided to ask about this issue that randomly rears its ugly head…

The Setup
Fairly well-regulated blood sugars (A1C of 6.8 for, basically, the last year and a half), fairly regular exercise regimen (3-5x per week but not an athlete by any measure), generally don’t suffer from overnight lows.
The day of the event: I’ll have breakfast with 20-30g of carbs and dose accordingly, lunch of ~50g carbs and under-dose, set my pump to “exercise”, wait for my numbers to come up to ~190mg/dL (or higher), then exercise. The worst offender seems to be Hatha Yoga with lots of held challenging poses.

The Event
Blood sugars will generally return to normal for the rest of the day and I’ll have dinner with ~50g of carbs and go to bed with stable numbers. Then, around midnight or 1am, there’s a sudden crash in BG and all the alarms wake me up to deal with the low.

I’m asking about this because it isn’t consistent with just any exercise - I also row (sprints and steady-state), do body weight stuff, Vinyasa/Power Yoga, and have lifted in the past - and they don’t seem to give me this trouble so I’m left wondering what’s special about Hatha. I know it’s not from my pump (Tandem T-Slim X2) giving me a bolus since sleep mode only provides basal insulin (although its target is low enough to make me uncomfortable). My endocrinologists and internists haven’t had much in the way of answers when I ask them, either. Does anyone have an idea what process is happening overnight and if there’s any way to prevent or prepare for it?

What’s the target? As we were just discussing in another thread that’s current, Tandem CIQ is very sensitive to Basal rate - have you tried lowering the basal rate during sleep? What happens then?

Are you usually very stable during sleep? So that this is an anomaly?

Good luck!

It’s odd that this happens with Hatha yoga but not other exercises. One cause of delayed hypos after exercise is the skeletal muscles replenishing glycogen stores. They can suck up glucose without the need for insulin. This can occur hours after the exercise.

Shari Colberg recommends a glass of milk to feed those hungry muscles. I can’t quote because I gave my copy of Diabetes for Athletes to a nurse in training to be CDE. I need to get another copy.

As I said I’m a bit confused why only with the yoga.

Thank you for the replies, all!

It looks like CIQ starts modifying basal delivery below 112.5 and above 120. My recollection was that it was targeting something lower like 110 or even 90 so I’m glad to have that sorted.

No; because I’m generally very stable during sleep, I don’t want to fiddle with it.

My guess (and it’s just that: a guess) is that Hatha causes it because it’s a more-static type of effort (whereas lifting, cycling, and rowing are all very dynamic). I can’t recall the word or phrase to describe it by I had an instructor explain that it’s challenging, even to the strong, because of the slow-to-no movement and it uses a different kind of muscle process…? I’m struggling to remember a conversation from about 4 years ago and we’ve had a pandemic since then :sweat_smile:.


Just ordered a copy; looks like a great resource!

I exercise daily and it doesn’t affect my BG levels at night. But when I snorkel for 2-3 hours once to twice a week I have a separate program for the night that gives me half my basal rate for a few hours before bed and about the first 4 hours of sleep. This usually works well to stop drops. Usually, not always as the conditions can really vary. I have an Omnipod though and have the ability to have different programs set up to choose from.


I’ll have to check if the Tandem has separate programs like that or not; I’d rather not fiddle with the settings if I only have one program to modify but it may turn into a necessity… who knows.

It does. You can use their two standard ones- for sleep and for exercise (which you can schedule or turn on manually). You can also create customized programs if you want - maybe for the particular exercise that gives you concern?