I was testing some stuff yesterday and I activated a pod but did not have it attached to my body.
After it activated, I did a bolus and watched the cannula. It took about 0.3 units before anything started coming out of the end of the cannula. Makes sense, the cannula is initially full of air.
So when you start a new pod, you may want to do a small unnecessary bolus to get rid of the air, or add a little bit to the bolus amount of whatever you are trying to take.
Otherwise your first bolus will be a little short of what you are intending to take.
I usually bolus a small amount with the old pod right before I change it but I think I try your suggestion next time!
Thx- I hadn’t thought of the air. I just thought it was something to do with the newness of the site itself. .3 or so less for me can mean definitely hitting 200 for a hour plus.
I had been starting new pods with a bolus of 0.25 to 0.5 depending on trend and mood. Now I can think about that 0.3 air gap and adjust accordingly! Thanks for the heads up!
If you are running Loop, you can see in the code that they do prime the cannula with 0.5u at insertion time, and you can customize the code if you want to add even more.
In LoopWorkspace/OmniBLE/OmniBLE/OmnipodCommon/Pod.swift find the line that says
public static let cannulaInsertionUnitsExtra =
and change the number from 0.0 to the amount of additional prime you want.
The code above that line shows that they do already prime it with 0.5 unit to start, but for me I want another, additional half unit to help get started smoothly.
When I start a new pod with loop-dev they ask me to confirm that the pod is attached, then I have to slide the control to start the insertion. After I do that, I hear the pod go tick-tick-tick-tick-tick-tick then WHAMMO as it stabs the cannula into me, then it continues to go tick-tick-tick-tick several more times. I presume all that ticking is the cannula priming, in accordance with the cannulaInsertionUnits and cannulaInsertionUnitsExtra values. I haven’t tried it with a pod that’s not attached, to watch if any insulin really comes out of the cannula, but I suppose it does. Do you hear ticking before the cannula inserts? Any additional ticking after it stabs you?
Thanks! I actually never noticed but I will check on my next pod change. 0.5U would be a lot of insulin for me if it actually had any effect but I’m assuming this would not really used by the body.
That’s what I’ve always assumed as well. The user manual confirms this: After you fill the pod, “The System performs a series of safety checks and automatically primes the Pod,” and then, “Once the cannula is inserted, the Pod delivers a prime bolus to fill the cannula with insulin.”
Nevertheless, as per @Eric’s post, I always do a 0.5U extra prime, theoretically to kick-start absorption. I’ve never read anything scientific to back up that idea, though.
@Beacher,
You can observe this by activating a pod that is not attached to your body. After it “inserts” into the air, and after it has finished it’s “priming”, do a bolus.
Observe how many clicks you hear before you actually see any insulin coming out!
Their priming is always a little bit short!
Giving too much insulin when a person attaches their pod is bad for their company. It would immediately get flagged and would be highly publicized! But not fully priming the canula is something that nobody notices too much.
I always thought doing an activation bolus was helping with absorption. But now I see it is merely getting rid of the air in the canula and making my basal delivery start working immediately. Otherwise I would be waiting an hour or more before I got any basal.
@bkh and others reading here: Not that I don’t trust @bkh, but since the question/comment has been raised, I’ve gone to the “horses mouth” as it were and posted the quoted line on LoopZulipChat for the developers comment. While it seems to be exactly like @bkh indicates, I’ve learned the code names sometimes don’t necessarily mean what they imply. I’ll post what I find out, may be a day or so…
Checking up on my assertions is a good practice, and I applaud you for doing it. I wish more people these days were skeptical of what they read until it’s independently verified by someone who actually knows, rather than “verified” by unsupported assertions from the “often wrong but never in doubt” crowd.
In fact, I was not thorough enough to read the code to see if the variable actually does what the name suggests, although I do think I hear more post-insertion clicks than I used to, so that gives me some belief that the extra prime is working.
I bolus .5 units after I change a pod. Sometimes I have noticed it’s a little too much so it’s nice to know .3 is the more accurate amount and why I’m doing it lol!!!
Someone had mentioned .5 dose as a solve for them when an op was saying their BG level went up after they changed their pod and wondered if anyone else had the same problem. Seemed to make sense to start doing it! I think I have always thought it helped kick start absorption!!!
But it makes sense they would short the priming dose “just in case”. Can’t have anyone have any chance of getting extra insulin!
On posting to LoopZulipChat, the developers site for Loop, I was referred to: Custom Edits - LoopDocs. @bkh was correct and this link provides the directions for changing it. Thanks, @bkh for the info! As for the amount to do, that’s probably variable (YDMV), but for Omnipods the resolution is .05 per “pump” cycle, i.e. each click so there’s quite a spread available. While there’s safeguards built into the code, if you make a modification, please double check what you enter!
That’s our bazillionaire products tester @Eric filling a pod I bet to 200u to test & put right into the oval file. That is unless you got some way to magically put that active pod onto your body…
I finally checked this over the weekend, and yes, I do hear an additional 3 clicks of the pod AFTER the cannula is injected. I think 3 clicks (unless I mis-counted the clicks!), is equal to 0.15 U of insulin. I do not have any custom edits and am using the dev version of Loop, v3.3.0.
How about this for a wild guess. 6 clicks before insertion + 1 click during insertion + 3 clicks after makes 10 clicks, 0.5u. Today is pod change day for me, so I’ll try to remember to count and see if I get 6+1+13 clicks for my supposed 0.5u + 0.5u.
That’s our bazillionaire products tester 
