How to stop peaking up up and beyond when BG rising

I’m not sure how to resolve this issue. I bolused for lunch, my I:C ratio appears correct - it started about 4mmol (72mg) and exactly 4 hours later landed just under 4mmol - maybe it’s a bit stronger than it should be but for the purpose of this discussion, let’s just say it landed at 4mmol.

My question is how to mitigate the spike up to 14mmol (252mg). I had preboloused 20 mins before my meal.

What was your meal?

Really can’t remember, I was just trolling through my graphs to fine an example that demonstrates this problem. It was probably a small homemade dinner roll with egg, avacado and cheese. And a cup of blueberry smoothie (blueberry, milk, yogurt, small spoonful of honey)

I forget, tedos, sorry, what’s your tech? Which pump? Also, shouldn’t you be coming down within 2 hrs? Why is it a 4 hour spike? Just by glancing at it, if it were me, I would increase that meal dose by 50%. Is this bolus bringing you back down to baseline or basal? I ask because we see you bump it up, and then it starts falling sharply down again. Whats up with this? Just curious.

Is this breakfast?

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I was seeing postprandials like this recently. I got sick of them and set the basal ultra high so that I am skimming right along the lower limit. It got rid of the post meal highs, but I gotta watch the lows now. I eat super high carb and I know that you don’t, so I’m not sure why this is happening to you, but its a little softer to just bump up the basals, rather than bumping up the bolus (which can lead to those post meal lows).

I’m on the tslim with the dexcom G6. This was the graph for lunch. It’s the bolus that is bringing me down. I don’t have control IQ so no adjustments in basal.

And with the circle part, it’s probably because I started getting hypo symptoms and had something to eat so it went up. That part is irrelevant in the context of this post.

:thinking: hmmm i think you are right. Maybe this is just an outlier event. But i also though the way to tell whether the I:C ratio is correct is looking at the BG at the start and looking at the BG 4 hours later and seeing whether they are the same and if they are then your I:C is correct

Edit: actually I isn’t it after two hours you should have reached your peak and on the way down, and after four hours back to the BG you started? :thinking:

I worry if i do this, I will go hypo 4 hours after bolusing.

There are three controllable variables in the BG management; 1) carb intake, 2) amount of insulin injected and 3) exercise. For given carb intake, you give pre-bolus and bolus the insulin amount per your estimate. The remaining controllable variable is “exercise”.

If you just walk around approximately 30-45 minutes after meal, the BG should start to decrease after 20-30 minutes walk. If the BG decrease rate is less than 1-2 mg/ul (per 5 minutes) at this point or 15 minute after, I will give a post-meal bolus of 0.5-1 units (approximately 50-100% basal in one hour), because either my insulin to carb ratio is not correct or/and my insulin resistance is high for whatever the reason.

If it turns out, the post-meal bolus of 0.5-1 unit is too much, I turned off pump at an appropriate time to prevent low. Basically, I borrow the equivalent of half hour (or so) worth of the basal injection to off-set the peak. Remember to turn off the pump for the same to prevent the low.


Yea, I can only increase my bolus so much before I start seeing severe lows, so if I can’t do it that way, then I need to increase my basal. I’m scared to tell you to do that, though, just incase it might be the basal that’s dropping you (that would already represent a high proportion of basal on board). You’ll know.

Insulin: Carb = 2 hours
Correction insulin = 4 hours.


Do you know what it means to “super-bolus”? I’ll let you Google it on your own. I’m not a big fan of a lot of the explanations I read. Essentially though, it lets you borrow some extra insulin from two hours of future basal. You should be able to add two hours worth of basal insulin to your pre-bolus, and trust Basal-IQ to suspend the extra insulin from your basal later. This means you get extra insulin up front to cover your post-prandial spikes.

The catch is, you’ve got to have your settings correct. It looks to me like your correction factor is too high, so it’s not suspending enough insulin soon enough to prevent the hypos 4-5 hours after the bolus.

More insulin up front, reduce your correction factor so you get less insulin on the back end.

You made another post recently where all your insulin was being suspended during your pre-bolus and then you still spiked high afterwards. You would still want to super-bolus to cover that coming spike, but in a case where you’re trending low like that, it’s time to eat. You don’t have to wait that whole time if you’re predicted low.

It’s a lot of little innuendos to figure out… The super-bolus is the greatest advantage I know of for us carb eaters. Without it, your graph is exactly what’s to be expected, and why so many diabetics find it easier to just low-carb it.

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Starting meal with more fat/protein first, and delay of the smoothie may help level the hump. Postpone dinner roll or split and have 1/2 later.

Some use the term “eat to your meter”, or “eat to your cgm” (also called sugar surfing).

I don’t quite understand this. Are you saying carbs should go down to pre bolus levels after 2 hours? I rarely have this happening. The insulin has a 4 hour duration, if it takes me down to pre bolus levels in 2 hours, it has no where to go after that then even lower.

Out of curiosity, how did you infer this from the graph? I’m trying to learn how to read the graphs :sweat_smile: so I can make better adjustments. I didn’t give any correction for this meal though.

I’ll have a look at the super bolus, thanks- it sounds like its just bolusing more than you need and having basal IQ save you from any extra. I don’t like to rely on basal IQ though, that will mean my sensor reading must be correct at the time too. :sweat_smile:

@MM1, are you thinking its the carb from the dinner roll that is causing this?

I’m actually suspecting its the smoothie. I have the same dinner roll all the time during breakfast and it doesn’t overshoot like this. If I delay the smoothie, that would only mean the hump will move out doesn’t it?

tedos, is there any value in us starting from scratch a bit? Like, asking which insulin’s your taking?

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:sweat_smile: Perhaps. Seems like my understanding of how things should be is a bit off. Sorry about that.

I’m taking novorapid.

My sugars rarely drop back down to the prebolus BG within 2 hours. 3 hours maybe but 2 hours it is still on its way down. Does this vary from person to person or is it generally a rule that if taking carbs it should be down within 2 hours?

It should take 2 hours, but I don’t want to get too far into the weeds without just covering our bases, incase we misunderstand something.
Your a type 1?
How long have you been on this pump?
Can you post the last 3 days of Dexcom data? That might help somebody get a bigger picture understanding of whats going on.

tedos summary
Type 1 on Dexcom
Short term insulin via tslim pump (no control IQ): Novorapid
I:C ratio:
Basal rates:

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Actually, I got that more from your earlier comment in this thread that your go low later if you took extra insulin. If you’re afraid to take extra insulin, and KNOW there will be a hypo, you’ve got to lower your correction factor. That’s what the pump uses to calculate how much insulin it needs to withhold to avoid the hypo. Though the fact that you did indeed go low after all that suggests the same. The pump had plenty of time to withhold basal, but didn’t.

And yes, it requires using pump automation as a tool AND trusting your CGM. It’s why I don’t understand why people are so reluctant to calibrate. Calibration works wonderfully if you do it at the appropriate time.

Though, super-bolusing has existed since before pump automation, people just did a manual suspension later based on how much IOB remained.

Which just reminded me of a second possibility. I forgot you can still change your duration of insulin action (DIA) in the settings. If you’re worried about lows on the backend, you could try increasing this setting. That would tell the pump you have more insulin on board at the 4 hour mark then you have it set to now.

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Mine average 2-3 hours, but I am doing lower carb/more fat/protein then your example. I use extended bolus in some cases.

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Your a type 1? - Yes 20 years
How long have you been on this pump? - Tslim since July this year. Previously on Medtronic

Can you post the last 3 days of Dexcom data? That might help somebody get a bigger picture understanding of whats going on. - **Not just yet. I just started on CGMS a week ago and adapting to it. I don’t think i have 3 days that represents my typical day, alot of the times I bolus less and exercise after a meal so not reflective of this scenario. Let me generate more data first. **

If we zoom in on just the issue of BG spiking too high after meals and not going down soon enough (ie 4 hours instead of 2), there must be something I’m not doing right. Not all my meals spike above 10mmol (180mg) but this was the obvious one in my graphs that I can find.

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Ah I see. From what I have been taught, it has always been a 4 hour window, the BG at the time of bolus should return back to roughly the same place 4 hours later. It is only earlier in this thread I learnt that this is not correct and it should be 2 hours. So in the scheme of things, my correction factor is actually not too strong because the intention was always a 4 hour window. If it’s two hours we are aiming for, then definitely too strong (either correction or I:C ratio or both), but if i reduce it and make it weaker, I can see myself peaking even higher than it is already doing.

Yeah, at the moment this is set at 4 hours which is roughly where I can see from my graphs it becomes used up and the rest is basal kicking in.

My rule… take everything you’ve been taught as a starting point, not a gospel.
There is never an “always” rule!

To me, the greatest thing about pump is that you can add precise bolus as needed, or suspend/reduce/cancel insulin currently being delivered.

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