Lack of sleep and high blood sugar

Last night I couldn’t sleep. I was still awake at 4 am. When I got up this morning my blood sugar was normal. I ate my normal breakfast and went to my normal ballet class. My blood sugar sky rocketed. Really high. I I corrected and took class, but halfway through I got dizzy and had to stop. My blood sugar was still high. It has now finally come down.

So is it normal to have high blood sugar after a sleepless night? And is it normal to get dizzy if you exercise with high blood sugar?


I can only speak for myself, rather than what is “normal,” but my blood sugar control certainly suffers when my sleep pattern is disrupted. Best examples I can think of, for me, come from regular travel for work. In addition to stress, I get about half of the average amount of sleep on work trips that I do at home. Even when I eat the same things (on the first couple days of travel when I can bring my own food, realistically), my BG is demonstrably worse after a redeye flight, when I only get 3 or 4 hours of sleep in a hotel, or have to get up super-early because of a time-zone shift.

I don’t know about the dizzy part and high blood sugar. For me, dizziness while exercising is usually a sign of a blood pressure drop, which is often about low blood sugar (for me). One of the reasons I’ve gravitated to lifting heavy weights for exercise or HIIT rather than extended endurance sports (cycling, running, etc.): for me, I have an easier time managing my BG and avoiding very low glucose and blood pressure. That low sugar/low blood pressure combo, I’ve figured out, is really scary to me: I’ve fallen off my bike (once), or almost passed out in the gym, and in both cases my BG was less than 60 mg/dL and my blood pressure was in the 80/50 neighborhood.

In both cases, eating some carbs helped to bring both BG and blood pressure back to “normal,” or at least close (my blood pressure always runs on the edge of clinically “low”). Is it possible that you overcorrected and were actually low(ish) during your ballet class? I suspect ballet would be pretty good at lowering blood glucose pretty quickly, and in combination with a correction may have led to a mild low or a drop in BG quick enough to cause some hypo symptoms. Is that possible?

I have sleep apnea. It is abundantly clear to me that a bad night of sleep affects my blood sugar. It can cause me to be insulin resistant all day. There are clear explanations about why that occurs. If you sleep poorly your body releases cortisol and other hormones. This makes you insulin insulin resistant. Although I treat my apnea with a CPAP, if I have a bad night I inject extra insulin first thing in the morning to offset these problems.


Yes! it does for me. I have trouble all day with insulin resistance when I o nt sleep well.

I don’t usually sleep through the night. Haven’t for decades. I see no correlation whatsoever in my early morning bg’s and sleep, OR my post-breakfast bg’s. Now that I have a Dexcom, I can see that while I’m sleeping my bg’s are near 100, which is great. Before the sensor, I’d sometimes wake up at 3 or 4 w/ bg’s over 200. I can maintain a much better bg level, as IF I go above a preset bg, it alarms, and I can respond appropriately to the bg number–either ride it out, or take a correction bolus. But again, I’ve never seen my bg’s correlate to if I slept soundly for 6-6-1/2 hours, or woke up 3-5 times.

I suppose it’s possible. Dizziness usually comes with a low for me too. My CGM did not show me low, but I’ve noticed my CGM is very slow to come down after a high (or up after a low for that matter.)

Thanks to all of you for your input. I usually sleep fine so this is a first for me and it’s good to know this is just one more anomaly to deal with. And it seems i"ll be insulin resistant all day because I went high after lunch too. It’s just a frustrating day trying to be my pancreas.


My lack of sleep is usually driven by my attempts to lower a stubborn high or (very rarely) an annoying low.

When insulin resistant, the only way out of it ( for me) is drink tons of water, change out my pump, do not eat anything until I start to trend down on Dex.

One think that has helped me is to “stop” taking it personally when BGs get wacked. . After 50 years, I finally adopted the mantra, " see this as data, use it for knowledge , and do the best until it gets back."

I like this, especially, “use it for knowledge.”

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Yep, it’s the cortisol that often leads to this common observation, just as the OP discovered.

When you are sleep-deprived, you’re running on adrenaline, which means cortisol release, which means increased glucose released by the liver. If you weren’t diabetic, your body could just use this for energy, but for us, it just makes it all harder. One thing to keep in mind is being careful, because after correcting those stubborn highs, your body may eventually be at greater risk for lows, since at some point your liver can get depleted. I suspect it’s part of why for me, when that kind of high finally responds, it tends to be suddenly with a big crash.

The dizziness may come into play not so much due to your blood sugar but because of your sleep deprivation. The above described responses of your body to not enough sleep happen in order to drive up your sympathetic nervous system activation, which makes your heart rate higher and more reactive. That’s how that adrenaline that’s compensating for your not being resting is managing to keep you awake and going, sort of like natural caffeine. Sudden upticks in SNS activation and in heart rate can make a person very dizzy and feel similar symptoms to when you might be low, even though you aren’t. Your heart rate normally goes up when you exercise but when sleep deprived, it may be happening to an extent that’s uncomfortable. It’s part of why you may need to take it a little easier when sleep deprived. Annoyingly, caffeine can make that all worse. All good reasons to try to maintain good sleep habits!

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Thank you. This is a very helpful explanation.