FUDiabetes

Using CGM for Insulin Dosing

My husband brought this editorial to my attention since I do generally dose off my CGM readings.

I did a quick skim, but I question the fairness and motivation of the article as it makes no mention of Medtronic and its cgm with the 670g.

We dose from the Dexcom G5 readings.

I think the author overlooks the value of our experience with CGMs over time, i.e., that we learn to recognize odd, not-quite-readings and confirm accuracy with meters.* He makes a really valuable point that users need coverage for more test strips (beyond those required for calibrations) as part of this learning and verifying process.

*Though meter accuracy itself is a separate but related issue.

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We don’t dose with the CGM readings. Our CGM isn’t accurate enough to base any decisions off of it…even though it should be. Might just be Liam’s age that results in our differences. But, often times the “15 minutes”, for someone his age is enough time to take a BG from 250 to 150 (or lower). So, before we administer insulin we always finger prick. We have been known to give snacks for CGM “low” readings, though, because there’s less potential damage from that (short term.)

We hope to get to the point where we can dose from the CGM, but we’re not there yet.

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The BG volatility associated with growth spurts and hormones is mind-boggling!

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For me, the G5 is crazy, crazy accurate. At least so far (just started last week). Discrepancies between it and meter readings is very negligible. Every time I second-guess the G5, I find I’ve wasted my time checking. :slight_smile:

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I am reasonably confident when there hasn’t been any food and/or bolus insulin in several hours that my cgm is close… after eating and or bolus though mine can be way way off… usually failing to recognize significant spikes until long after I’d have wanted it to…

I’ved learned to watch for–and check–the treated low that doesn’t want to go up…and just the other day, the previously treated high (170) that was actually down to 116. :grin: :stuck_out_tongue_winking_eye:

Agreed. Our calibrations are usually within single digits of the meter and cgm.

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Sam, even after eating or bolusing, the G5 doesn’t ever stray far from meter readings. Perhaps your swings are more severe than mine—who knows, just reporting my experience with my first sensor. I may find another sensor doesn’t work as well as the one I have now, but I hope not! I used to be an Enlite user, or as I like to refer to them–“random number generator”.

Mind if I ask what meter you are using? I ask, because when I was using the verio one touch, my cgm and meter were often at odds, but since switching to the contour next ez, my calibrations are almost always spot on.

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I think this really varies with individual sensors and their placement. We’ve had some that are spookily accurate. Most are fine when roughly flat but overestimate lows and lag on registering highs. This current one is somewhere between random number generator and ballpark trend estimator. It has the scalloped pattern and the triplets I come to associate with either a fresh or a dying sensor, and has so from the beginning. A lot more finger sticks and surprises, but not quite enough to subject Samson to an additional sensor change just yet.

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@Dave, welcome to FUD! We have an Introduction Thread so people can find out about you, if you want:

Our G5 readings are, in general, accurate, when our calibration is good. We often dose from the CGM readings. But there are many circumstances when we will feel the need to manually test first. I agree with @CatLady when she writes:

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Welcome, @dave!

We love our Dexcom, and we dose from it too! But I have posted and documented several patterns on this forum where you can see the G5 is way off, in particular in transitions. One example:

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I guess I dose from my Dexcom readings–if I feel they are correct. It’s really not very often that it is wrong, but invariably I’ll know if it’s wrong and I’ll check before dosing.

I opened a new box of sensors the other day and there was an instruction card I hadn’t seen before that explained how to dose from the Dexcom readings. It basically said that if you think the Dexcom is correct then dose from it. If you feel that it is incorrect, then check on the meter.

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Common sense? On the other hand, good advice for new cgm users.

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Alas, common sense is all but common.

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PWDs who participate in the DOC or who have very experienced trainers or CDEs get to know the quirks of these devices pretty quickly. But I suspect we’re in the minority as yet.

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Before the FDA decision (Dec. 20, 2016), Dexcom was actually barred from giving this information out. Common sense to some people but for somebody who might be new or really doesn’t understand the technology in the slightest then it might be helpful. I think we first saw this in our June or July shipment of sensors.

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I’m pretty confident that they meant to listen to your body–if you feel low, or high (and that feeling runs counter to a CGM reading), then double check by taking a finger stick reading. Same thing applies if you take a finger stick reading and feel that it is way off–test again. I’ve been saved from over bolusing 2X that I can remember, by my wife who cautioned me to not believe my meter when dining out. I had BBQ sauce on my fingers which caused a false, very high reading, for which I would have bolused accordingly. I washed my hands thoroughly and retested–bg normal. Same thing happened again, due to BBQ sauce residue. Couldn’t see the residue because it was so slight, but enough to goof up a meter reading.

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