Blood Sugar increasing during the night

The last two nights my blood sugar has increased to high levels while I am sleeping.

When I went to bed on Friday night my sugar was 146 and it had been around that number for a few hours, when I woke up it was 263.
Saturday I went to be with my sugar at 150, got up at 2:26am my sugar was 264 gave myself 3 units of novolog when I got up this morning my sugar was 236.

I take my Lantus 20 units at night.
I have not had this happen in the past. I am type 1 since 5/23/16 and have not had this happen in the past. I have gone low in the night and had to get up to treat that in the past. I have the G5 cgm and got it about 6 months ago.

Any suggestions would be helpful

There could be multiple explanations, but the 2 most likely culprits are dawn phenomenon and eating meals that digest for hours and spike you after your bolus insulin has run out. You haven’t been type 1 for too long, it’s possible your body was still producing some insulin (the honeymoon phase) that was compensating for either or both of these issues, and now your natural insulin production is running out.

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Especially around the transition to fall, I often see a big rollercoaster in my bg’s including like you note higher numbers in the morning.

I think the cooler weather during the night, or just the longer darkness at night affecting my sleep cycle, is a trigger for dawn phenomenon in the fall that didn’t happen during the summer.

On top of that, I also have some fall allergies so I often feel fuzzy-headed from the allergies and think my bg must be low. Then I check, and nope, bg isn’t low or it’s crazy high from the dawn phenomenon.

The general answer to your situation is that you need more insulin. Your challenge is to figure out whether you need more meal insulin for your evening meal or more basal insulin (Lantus) insulin.

I try to eat my last meal of the day relatively early in the evening so that most of the blood glucose/insulin action happens before I go to bed. What time did you eat your evening meal on the two days you write about? What did you eat?

You may test your basal insulin needs by eating the last meal of the day early enough so that five or more hours elapse before you go to bed. Then set your alarm to fingerstick and record your blood sugar values during the night. You may read more about one basal testing protocol at Gary Scheiner’s website.

While you are trying to adjust your insulin dosages it may help you to eat the same meal for a few or even several days in a row. Keep a notebook that can record your blood glucose levels, insulin doses, timing, and any other factor you might think is pertinent. Some people notice better overall blood sugar control is associated with a full night’s sleep.

Be aware that there exists no single perfect insulin dose for you. It will change and the best thing for you to learn is how to adjust when these changes happen. That’s why staging an experiment, like the basal test, is useful.

Good luck! You are asking the right questions.

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that’s why I pump. I have a much higher basal after midnight, then the rest of the day. Lantus is too flat to cover the peaking bg I’ve experienced for many years, during the night. Who wants to inject a bolus when they go to bed, to try to prevent a possible peak? A pump allows you to set different basals throughout the day and night. I have 6 basals set up in the pump. The lowest is .5/hr and the highest is .875/hr

[EDIT] since I’ve been eating more sensibly and dieting for the past month or so my basal has been reduced at night to. 6 and my total insulin per day is dropped into the twenties from the usual 35 to 75 per day. The side effect of that is less lows from over bolusing and less worrying about my blood sugar level

I’m having a similar thing going on. But mine is low for the past two days and then spikes up while I sleep and as I wake up takes 2-3 corrections to come down. I’ll have to try an injection instead which I don’t like to except for emergency type highs. It has finally come down now after the second correction but it took several hours- the first correction had no effect. Mine was not that high although Dex showed me 268 it was 169 finger stick. This sensor is the worst In a while but then it goes back to being accurate for a while.

I think mine may be due to eating my dinner before I sleep the past two days and a schedule change but I’m not sure. This whole week has been bad with it being high before I slept a couple of times too and not coming down from corrections. Because it was low the past two days I didnt do as much overnight basal increase and one I corrected with juice with arrows down. This last one I’m not sure what’s up. Probably my thyroid issues overall as well as the other stuff.

I used to use Levemir twice a day and had to use a bigger dose at night.
Now I am on the Tslim X2 and have 3 time of day basal adjustments. I use more from 12 to 3 AM. Then less tilll 11 AM.
Then normal levels.
My A1C is around a point lower now and I think it is mostly due to the more precise basal control.

After much experimentation, I’ve found for me only a very low carb diet (<20-30/day) prevents my BS from going up overnight. If I eat more than that, which I typically do, I have the basal setting on my pump set to give me almost double what I normally get between 12a and 6a.

I’d suggest slowly experimenting with Lantus dose, and/or seeing if what/when you are eating at night could be having a role.

For me it’s always been about gradual experimentation until you find what works for you! Good luck!

In my experience I have usually done one of these two things when my BG skyrockets in the night.

  1. I ate a very large greasy meal with lots of fat that is breaking down long after my humalog has worn off.
  2. I ate my dinner to late (which I try to NEVER do as it is dangerous) and didn’t give myself time to check my BG 4-5 hours after my dinner time bolus. I eat at 5-6pm everyday so I can check my BG at 9-10 and again right before bed.

I can’t tell you how many times my BG was perfect two hours after a mealtime bolus then 150 points higher 2-3 hours later. I guess the 3rd option might just be the nature of the beast. I find every few weeks I get 2-3 days of crazy unexplained BG trends. I just try to be mellow and keep my cool, make corrections for highs and not jump to action and make any changes to basil and carb/insulin ratios that have worked well for me in the past. If you eliminate the obvious culprits (1 and 2 and dawn phenomenon) then I’d just stay on track and you should be good in a day or two. I know it is painful to wake up with high sugar. That is by far one of the most frustrating diabetic experiences. Good luck and keep your head up! :slight_smile:

Thank you for your response, there is so much that goes into this that is it difficult to figure out sometimes.


I didn’t know if it was the weather and the fact that there are more blankets on the bed which made me get hotter at night.

I want to thank everyone for the responses, I see that it could be a number of things happening.
I still have a lot to learn about the D!
I am also trying out a new endo next week, so I am hoping to get a little more help than I get with the current one.
Plus I will continue to learn from all of you. I am on here pretty much every day and have learned a lot! I read Think Like a Pancreas and Using Insulin when first diagnosed. I think I will read Using Insulin again and also go the website Terry suggested.
I am thinking about a pump but hear about all of the settings and things that people are doing with the pumps and it seems a bit overwhelming and a lot to keep straight.

Thanks again Bev

I agree with @Terry4 . Over the years I learned that it is ideal to have dinner 4 or more hours before bedtime so that most insulin on board is used when I check my BG before bed. If I am high I may increase my Lantus from 6.0 to 6.5. I may also take a small dose of Humalog. Do not do this unless you are very confident. It can be dangerous. My endo strongly advised me to avoid short acting at bedtime. I have learned what works for me. I always err on the side of caution - I take a bit less than I think I should.

Being sick can also impact your BG. Mine are much higher and my insulin is less effective when I have cold / flu / etc

Good grief @Terry4!! You are running Loop. What’s the point of all the time and effort spent setting up your DIY Artificial Pancreas if you aren’t going to give it a good workout. I suggest a 16 inch deep dish pizza, followed by a large bowl of strawberries and chocolate ice-cream. Don’t start eating until around 9 pm and make sure you accompany your meal with at least a half of a bottle of wine.

Bolus for half the carbs only… go to bed and when you get up the next morning, enjoy the straight line…


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I’ve observed that there are limits to what Loop can control for me. We each must play the hand we’re dealt. For me, I must also deal with some digestive issues including GERD and gastroparesis.

Regarding the pizza and ice cream suggestion, Joel, you must have written this with tongue in cheek??! Perhaps your point is that I should push my system more since I have some good technology. I’m happy with my strategy and tactics using my current routine and will continue to keep my eyes open for new ways of managing my diabetes.

Congrats on your success with OpenAPS.

Err… No actually pretty close to what I do. OK, so it was Fish & Chips and I didn’t have the strawberries with the ice cream, but still pretty representative. I routinely eat pasta or pizza at 8 pm or later - typically ~90g carbs or more. I actually find I stay flatter than with a sandwich at lunchtime. As long as the GI is low enough and I give it a nudge in the right direction, OpenAPS will pick up the slack for the late digesting carbs. The problem is higher GI carbs, particularly now I have finally given up on Fiasp (or rather Fiasp/Humalog mix) and I need to remember to pre-bolus.

Push the system and see what it can do! Should actually be easier with Loop than OpenAPS since you can enter a carb absorption rate rather than having to rely on the algorithm to guess this (and AAPS is not great for anything longer than 4 hours or for protein which is why I have to enter half the carbs for 120 mins later)

Thanks for clarifying your previous remarks. It’s hard to discern the meaning of someone’s intentions sometimes.

I agree that my personal diabetes treatment challenge likely has more solutions than the one that I currently employ. I enjoy a bright spot that Loop combined with my two-meal/day lower carb habit gives me. I’ve also concluded that daily exercise is crucial to keep my sensitivity to insulin in a reliable range. I’ve explored the edges of my control with limited attempts with higher carb meals and have failed.

Ice cream, by the way, is my Waterloo. When I venture beyond a relatively small measured serving, I have universally failed. Each time I shake my head and wonder why I didn’t learn the needed lesson the last time I metabolically crashed and burned.

Each of our diabetic metabolisms varies. Some people get more help from some residual healthy beta cells. My c-peptide lab number is at the lower edge of the lab range. I also think the effects of food vary from person to person.

Since I respect diabetes as a dynamic condition, I know I cannot rest on laurels. Things change, whether I like it or not. I will continue to keep my eyes and ears open so I can arrive at new understandings from time to time. I appreciate reports like yours.