Pre-Bolusing screw ups

How do you deal with a watching-the-bend screw up? Twice in the space of 24 hours! First one was last night after a restaurant dinner I’ve had many times and never had a problem with. I pre-bolused about 15 minutes before food arrived with my BG at 98, ate and paid up, then 45 minutes post-bolus after walking the couple of blocks to my next destination I was suddenly whacked with one of those flashbulb-in-the-eyes lows. BG meter told me I was at 45 and vertical arrows on my CGM said I was heading south fast. Thing is, I knew I had carbs on board, they just hadn’t caught up to the insulin yet, which for some reason had come on way faster and harder than normal. So theoretically… do you just hang on and wait it out? In my case I just couldn’t do it and I don’t even know if it’s safe when you’re starting to have vision loss, sweats, can’t walk, just want to close your eyes etc. As it was I had a couple of cookies, forced myself not to scarf down the whole damn box, but two hours later my BG is up to 230 and I’m having to correct for that and roller-coaster here we go.

Funny thing is, it just happened to me again at lunch today—got stuck in a hallway conference after pre-bolusing, got my lunch late, went low for a while before the food could kick in, but not so bad and inside an hour I’m up to normal. But ones like last night—I’m really not sure what to do. Anyone?

I don’t know for sure but when I experience lows soon after eating I often connect it being too low at the time of dosing the pre-bolus. How confident are you of that dinnertime 98 reading? Was it CGM? It could have been 68.

My 60 minute breakfast pre-bolus and 30-minute dinner pre-bolus are fairly dependable for me but they are not 100% correct. If I see my BG trending toward a low after dosing but earlier than planned, I try to change my meal time. That’s not always socially convenient but neither is going flash bulb hypo after eating.

An explanation could be an over-bolused previous meal or basal that’s aggressive leading into the meal. That, of course could be from recent exercise making you more insulin sensitive than you usually are. There are so many moving parts, you’ll have to be the ultimate judge.

Not CGM, finger stick, so pretty confident. All the numbers are from my Contour Next’s log.

But really I’m curious less about causes—I have a pretty good sense of what the variables are—than about what it’s smart to DO when this happens. I suppose it’s analogous to exercise-induced lows, which naturally bounce back quite a bit if I can wait 'em out, but this seemed too risky for that. Maybe just because I’m familiar with the exercise effect on my own body, whereas knowing this was from just having dosed with insulin put a different spin on it. Well and it also felt a lot worse than those exercise ones, even though I’ve occasionally had those push me down pretty far. Just seems like kind of a gray area in treating a low.

Strengthens the case for Afrezza I suppose…

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We are very case-by-case on this for our son. If he’s running around, we throw a juicebox and deal with the high later.
If he has a belly full of cereal and we know it will come back up and he’s home, we may ride it out. For our son, having food in his tummy also slows the effect of things like glucose tabs anyways, so we find that it’s often best to just wait a bit.

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If I’m home I try to wait a bit. If out, or driving, or with no safety net, I’ll eat right away and deal with the high later.
Happens to me sometimes. I know I have had enough food to cover, but maybe it’s fat slowing the carbs down. And it sucks because you know you will end up spiking.

Yeah, if I need to treat right away with something fast acting (like letting glucose tabs/smarties dissolve in my mouth) for safety’s sake, and I know as a result I’ll end up high later, I’ll both treat the low and take insulin—the timing of the insulin if I take it right then tends to head off the rebound high. If I wait for my blood sugar to start coming up first, it tends to be too late and I’m playing catch-up with a rebound. That’s all only if I’m confident it’s a timing issue and not a mis-dosing one.

If I am home I try to wait it out, but if not, I will treat but not too aggressively. At least not at first. Hate it when it happens.

When this happens, I do correct it right away (usually with juice), and bolus 1/2 dose of insulin for the carb correction when BG gets back up to 70. Then I keep an eye on it, and if it goes up too much, I’ll bolus the other half that I held back from the carb correction. I’ve had a lot of success with this approach. Generally, my theory is all carbs must be accounted for. Just because you’re bolus got too far ahead of the carbs doesn’t mean they aren’t coming in later.

Also, when this does happen its usually because something not happy digestion-wise. Usually its nothing significant (like getting a bug), and straightens itself out. However, when things get hinky like this I stop pre-bolusing until digestion seems to be back on track in the next day or two.

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If I’m low enough to feel it (which is usually in the neighborhood of 50), I don’t wait. I correct–with glucose tabs if available, otherwise with whatever I can find. I would rather deal with a spike in the short term than risk serious impairment.

My general policy is, if I can figure out what’s causing an anomaly in 10 seconds or less, great. Otherwise I correct and work it out later.


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Wow, how you described your low, “flashbulb in he yes” so very perfect. I have just started having those kinds over he past few years and couldn’t figure out how to describe them. And that is it. Scared the crap out of me the first time, as I thought that horrible thought that I was finally going blind, like I was told so many years ago. So thank you for giving me a great way to describe that symptom!
And to the what I do, been there many times and for me it depends on where I am and who I’m with. If I’m at home with someone else in the house, I wait it out and just watch the CGM. If I’m out and not sure about surroundings, I do 2 tablets. Enough to help but not enough to end up high. And I just do a lot of CGM watching. But as Terry talked about in another post, pre-bolus is great but it can put you in a very scary place sometimes. Glad you got through it and as usual, there isn’t a cut in stone answer. As always with diabetes, every day and every situation is different. And how you handle it today, might be different tomorrow.
Flashbulb in the eyes! Love it!


I hate when this happens. I do what has already been mentioned. Sometimes th.ere just aren’t any answers for why

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Yes it’s happened to me numerous times. The best thing is always keep a roll of 4gm glucose tabs handy. Since the tabs taste fairly yucky, you’re not as tempted to shovel down several cookies only to hit the super highs when your meal carbs kick in. Take 1 glucose tab when you’re low. Wait 15 - 20 minutes, and your bg on your CGM should start coming back up. You might go a bit higher than you would without the glucose tab, but its pretty fast and 4 gms of carbs isn’t too much for most people.