I DO take the trend arrow into account when I make bolus decisions. While nobody should follow my recommendation because I am not a trained professional and because, to be candid, nobody will point to my CGM profiles and say: “Wow, this guy may be old, but he sure has his T1D under control …”
Note: I use a Dexcom G6 in concert with a Tandem t:slim X2 pump.
Let me try to use a very detailed example. For this I will assume that my correction factor is 50 mg/dL per unit and that my target is 100 mg/dL. Let us further assume that I have IOB of 1unit.
Let’s consider 3 different situations:
Current glucose reading of 200 mg/dL with a flat trend arrow.
Current glucose reading of 200 mg/dL with an “upward diagonal” trend arrow. In other words my glucose has upward momentum of 1-2 mg/dL/min. Note: I don’t know if “momentum” is an ADA-approved term, but that is what I call it.
Current glucose reading of 200 mg/dL but with a diagonal downward trend arrow.
I don’t know about Omnipod, but Dexcom has a bolus wizard to help with the math.
For case 1 the bolus wizard will say that I should add a bolus of 1.0 units. Why? My current BG is flat at 200 mg/dL, but the 1.0 unit of IOB should drop me to 150 mg/dL. So, the bolus wizard calculates that I need 1 more unit of insulin to drop me from 150 mg/dL to 100 mg/dL. Agreed?
For case 2, I’m at 200 mg/dL but rising. If we assume that it takes 30-ish minutes for a bolus added now to “begin to work” my glucose reading then will actually be something closer to 230-260 mg/dL. The bolus wizard will once again say that I need a correction bolus of 1.0 unit based on the current reading of 200 mg/dL … but I would likely increase that to 2.0 based on the fact that my BG is likely to be close to 250 mg/dL by the time it “begins to work”.
Finally, for the downward trending reading of 200 mg/dL, the bolus wizard will once again calculate that I need to add a bolus of 1.0 unit to the 1.0 IOB. But, after the 30-minute “activation time” of insulin, I know that my BG will have already dropped to something like 140-170 mg/dL … and that the IOB that I already have is likely to drop me close to 100 mg/dL. In that case, I would likely ignore the additional 1.0 unit that the bolus wizard recommended and give myself NOTHING additional.
Of course, for me, if the arrow is vertical up or vertical down … or worse yet double vertical up or double vertical down … I would likely make more extreme corrections to what the bolus wizard suggested.
Lest you think that this is just some “stuff” that I made up, here is a reference to a Dexcom document (in their health care provider section … not their normal user section) that more-or-less supports the approach that I am suggesting:
As I say, I’m not an endocrinologist or a CDE, so I suggest you check this out with your diabetes team before you try this. I keep hoping that the bolus wizards in our pump/CGM integrated systems will begin to do something like this for us.
Finally, if we assume that newer insulin’s will get faster and faster, worrying about the momentum of rising or falling BG becomes less of an issue.
At least that is the way that I look at and use trend arrows.