Are you insulin-resistant and slow to respond at night?

We have known for a long time that we (my T1D son) were slow to respond at night: from 45 minutes our response time to turning the corner goes up to 60-75 minutes.

Over the past few months, we have also figured out that our CF (correction factor) doubles at night: we use twice as much bolus insulin to drop the same amount. It is not good for us because we are typically cautious at night with corrections: this CF doubling often causes us to be needlessly careful.

We always thought that both of these were due to sleep. But the surprising thing we have recently discovered is that both facts, for us, are also true at night when we are awake: they appear to be connected, with us, to circadian cycles rather than sleep.

Is this also true for you, or is it a YDMV fact? Are you insulin-resistant and slow to respond to insulin at night? Is it associated with sleep or with time?


Nope, I experience the opposite. However, I’m not in the middle of puberty and am also taking metformin. So my situation could be totally different.

With Fiasp, my turnaround time is almsot instant overnight when there’s no food affecting things. And I typically use half my usual correction factor before bed and overnight, otherwise I’ll end up seriously low.

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Mine seems to be pretty slow at night. I always assumed it was due to low activity level that time of day for me, but not entirely sure.

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@Michel Yes and yes. I spent all of last night climbing up to 250. The 27 units (!) that I took at 1am didn’t get it to turn the corner until 5am, and at 8:13 (now) I’m at 90.

During the day that 27 units would have me turn the corner in 30 minutes and low in an hour.


Absolutely. When I test at night, I double whatever correction dose the PDM suggests.


My experiences closely mirror what @docslotnick posted. I can be 109 at bedtime with 2 IOB and a 105% basal rate and by 0330 I will be +250. The only exception to that I have found is when I eat mashed cauliflower and animal protein prior to 1830 hrs. Then my bg stays a rock solid 110 all night. If I eat past 1830 hours, no matter how good my bgs are when I go to bed, they will be mid to high 200s by 0300. It also takes me twice as much insulin and a 15% increased basal rate between 2100 and 0400 when I eat late (past 1830) or poorly.


My basal at night is between 25 and 60% of my daytime basal. Daytime basal rates would cause lows at night. Also, I’m always hesitant to give the full correction dose suggested by the bolus wizard before going to bed, because my BG sometimes drops quite much during the night.


Same here. Eating late is an overnight BS killer.


Yes, but despite this I remain pretty cautious about corrections at night because I hate those 3AM lows. If I can flatline at around 100-110 by 11PM, BG holds steady all night. If my BG is inadvertently rising when my head hits the pillow I will usually continue to drift higher to the 140-150 range over the next hour or two. This has caused me to run higher at night and waking than desired on many nights. Also seems to exaggerate the dawn phenom, requiring at least double my usual correction bolus before breakfast to drop BG range 50 points. Still trying to sort it out using bed time corrections at 9-11 PM range.


We had a rising high last night. At 250 BG, I did a 6 unit bolus, 33% up front extended over 2 hours.
(ie - 2 units now plus 4 units spread evenly over the next 2 hours).
The bolus was Fiasp from the pump.

According to the cgm, the climb was stopped in 20 min. The Basal-IQ caught it on the down swing and prevented a low.
Subtract the presumed delay on the cgm and the climb was apparently stopped pretty quick.

Since being active on the Basal-IQ algorithm, I am significantly more aggressive at nighttime.

Not only does the Basal-IQ suspend basal but it also cancels extended bolus. I also find that extended bolus works better (for us) to correct a high as opposed to a very large (relative - for us) single bolus. Combined together it means that at nighttime I feel comfortable giving a much larger extended bolus than I previously would give. It does a good job on the highs and if the extended bolus is too much then the Basal-IQ will cancel the remaining extended.

Of course the IOB is still present (when the Basal-IQ suspend activates) and there is a limit to what the Basal-IQ can do so one must be reasonable. But within the practical limits of the algorithm this has significantly increased the tools that I feel comfortable using at night.



Something awful, @Michel. I would show you my overnight pattern when I’ve eaten something, but then I wouldn’t be able to show my face around here anymore. :smiley:

I’m just learning it about myself. Unfortunately, the more I look, the more I see, and I’m really looking at whether or not it’s worth having a late night snack at all. As far as whether it’s sleep-related or time-related, I’d, at this point, have to lean toward the latter. As I don’t have a routine bedtime, I can say I see the same spike starting just before midnight almost every single night, asleep or not. It looks like a Stonehenge rock. Sadly, I can’t blame it on my basal rate because it only appears after my beloved late night snack.



@Nickyghaleb. I said that I was insulin resistant. And at night the stuff doesn’t even work.


I guess it doesn’t! :grimacing:

I’m a lightweight I guess. I get freaked out at having 10 units on board…

@Nickyghaleb I just took 40 units for dinner. Zaxbys 5 piece chicken finger plate with fries and Cole slaw. Dogs ate about one of my chicken fingers, half my fries, and the bread.

I’ll take the other 15 units of my split dose in about an hour and a half.

My Bg laughs at 10 u or less.



Your body eats insulin… there’s no other explanation. That’s a lot of insulin… and 15 more??

So I understand you’ve got a little insulin resistance, a slight understatement, but has it always been this way for you?

I can overdo it with one unit… like if I overshoot by a unit, it can mean trouble. Dang, diabetes… you are amazing. :grin:


I don’t even … if I have 4 units IOB at night I will almost always go low by 2am (excluding Thanksgiving night :grin:). I should be grateful guess.

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But sometimes…

Apple pie last night before bed. (gluten-free homemade)
Thumbing our nose at the low-carb concept.
(kidding - we may not be low carbers but honestly do not consider other choices people make to be “bad” in terms of carbs or not carbs)

Followed up later in the night by a six unit nighttime [extended] bolus but I knew that was going to be needed so it was all good. Bolus with the pie of course so I waited later in the night to see if that bolus would be adequate. It was not. As mentioned by a couple others, carbs late at night are like “super carbs”. So I did a 6-unit extended bolus around BG of 220 later during the night. The rise stopped at 235 and then started its downward movement.

Sometimes pie is appropriate.

(Pie is not actually an every night event for us.)


Depending on how much I’ve been exercising lately I can require anything from a little more than usual to double or triple a usual dose at night. But it depends how late (8PM is where things start going south and the later the worse) and it lasts until 10 or 11AM in the morning. Completely time and not sleep dependent. I don’t bother messing with CF and just try to judge based on time, experience, and recent history. I’ve been pretty good at it lately, but that’s because I’ve got a decent and fairly consistent exercise regimen going & have been eating pretty well.

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My PCP and Endo both think I am up to something nefarious because I claim that I routinely bolus up to the 30U maximum my Humapens and Novopen will dispense.

But my insulin resistance/carb sensitivity is so extreme that it isn’t a claim, it’s a fact…