Question about taking a bolus when tandem has shut off insulin floor due to low BS

Hi all,

I love all the advice given out on this forum. I try to give a little of my own when I can. Been dealing with Type 1 for 52 years. But I could use some advice now.

A question for the experienced Tandem/Dexcom users: I use the Tandem slim x2 pump with control IQ and the Dexcom G6 cgm. When I have mildly low BS and take a snack (let’s say 10 carbs) and I program that into the pump, it then gives me the corrected bolus, allowing that my BS is slightly below normal and adjusting for that. BUT- the pump has currently stopped giving insulin to avoid a (future) low BS. So: what happens to the bolus I just took? Does it still give it to me? Does it ignore it altogether? Does it wait until insulin resumes and give some/all? Without that insulin, I will be higher later… Some advice about how this works and how to allow for insulin shut off for a current low BS when anticipating needing more insulin very shortly will be greatly appreciated!


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Terri @TJC, I’ll try answering all the questions you posed; I have been using the CIQ algorithm since the time it became available.

The first and very direct question, “does it give the bolus?” - YES, it will give the entire bolus immediately unless you selected an “extended bolus”. When you say the pump has stopped giving insulin, I’m thinking you mean that BASAL has been suspended - bolus and basal operate somewhat differently.

I have been in the situation you describe many, many times and I’ll group the other queries together and tell my approach. I always look at the suggested bolus, my displayed BGL and at least 3 or 4 previous dots and then consider [and this applies to meal bolus, too] my activity over a few hours past and future, AND the food I will be eating. If I’m planning to eat a meal soon, I will not take any insulin with a small snack; when my next meal will be more than an hour away, I’d probably use “extended bolus” with 0 insulin now and the balance spread over time depending how fast the selected food will push up my BGL.

As always, you can always “override” the pump provided ESTIMATED bolus by either increasing or decreasing the amount. Terri, kind of think back to the good-old-days, 50 years ago when we guessed at our BS levels and ate what we “felt” we needed and IF we took insulin when we felt low. I know way back then, that I didn’t take insulin when I ate something when I was already feeling my BS was lower than it should be. You’ve survived 52 years, and probably are smarter than this new-fangled artificial intelligent pump thing - even so, I do like this CIQ thing.

I do not use that brand of pump but no one has ever told me to bolus for carbs to correct a low. Depending on your glucose just correct with the carbs. If you are eating 20g of carbs to correct a low that 10g should fix, bolus for half that but I would not do that.

Hi Dennis,

Thanks as always for your help and ideas. I think you are best, most experienced and helpful person when it comes to handling T1D.

I know what you mean about the difference between basal and bolus. I was just curious if when the screen goes “black” (stopped insulin) if a bolus would override it. You say yes. But I have noticed – and maybe I need to really check this out more thoroughly – when I took the .6 units for the snack (I’m super sensitive to insulin – require very little) – it did NOT show up on the pump as “.6 units on board”. It showed 0 units. I think it should show up, right?

On that same idea, my doc told me that when you are running high, the pump will UP ONLY YOUR BASAL rate – not give boluses - to bring you down. I think this must be incorrect, as I have often checked my pump, see my BS is higher than in range, and see that some amount of insulin (.4u, .8u, whatever amount) is showing as “on board”, even though I did not administer it. Your thoughts?


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Terri @TJC, if you have Control IQ activated and you are in either Normal Activity or Exercise Activity mode, your pump WILL automatically deliver an “Automatic-Correction Bolus” if your BGL ventures above 160 (?) mg/dl. It is only in Sleep Mode that the correction bolus is disabled. I suspect that your doctor might be thinking Basil IQ. If you venture to Pump History in the Options menu, and select “Bolus” you can see exactly what was delivered and at what time. A bolus that you initiate will be identified as Food/BG, and automatic corrections will be “Control IQ Correction”.

I’m not sure why you are not seeing a value in the Insulin on Board line. Another place where you can see your “Last Bolus” is in the pump status - touch the upper right of the pump screen, where the cartridge volume is displayed, and there appears your status at present along with your settings - I think there are three screens assessed by the down arrow.

If you use a “smart” phone, I suggest that you install the Tandem t:Connect Mobile App. at the touch of an icon, you can see, in nice BIG [good for dim eyes especially when outside in the sun] clear color your current BGL readings, the arrows and with a swipe of a finger across screen up to 24 hours of readings graph, all carbs entered, insulin delivered, with Automatic Correction pictured as a black drop - normal bolus is pictured as a blue drop. I see on my t:Connrct app that about 2 1/2 hours after last night’s supper, I received a 0.067 unit correction. A swipe up on that screen [Dashboard] displays many pump settings, recent history, as well as sensor start date and time and your transmitter battery condition.

Oh, for your safety and privacy, you may want to delete your personal data from this message.

Thanks for your ideas. Your are right! (I thought so) about the correction bolus. Thanks for letting me know about the upper right hand corner quick view menu - didn’t know about that. I have T:connect - love the larger font. And thanks for letting me know about the personal info showing up - didn’t realize - finally found the edit button…

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If you simply calculate the carbs and dose your appropriate amount of units of insulin it will be delivered. If your maximum dose is 15 units but you know you need twenty enter the 15 in units section of the pump, when it completes delivery of the 15 you can enter 5 units and it will be delivered as well.

More than 50 years T1D, same equipment as you. I’m very healthy despite the disease.