Poll - Dosing from CGM data alone

I really don’t dose off my CGM… anything more than very small, insignificant boluses. This is an example of the things I’ve seen that contribute to my thinking… My CGM was showing a fast rising trend, and having had TWO bananas after my run tonight, it confirmed what I was afraid would happen— a big rebound. I almost “took care of it”, which would’ve meant a fairly aggressive bolus (a true rebound off of 2 bananas could mean I was headed for the 300s). Almost. I decided to double check just to make sure… and saw the 117. Decided against the couple of units.

This isn’t to say other people have this problem, and there are plenty of times my sensor is just fine, but these kinds of instances just make me leery to bolus without double checking first.

Oh! And I should include in here that it actually was a rising blood sugar. I watched it for a while after this just to try to get a handle on what was happening, and my blood sugar did continue to climb to about a 140, but my sensor at that point was showing a ~185 with two arrows up. I’m glad I didn’t do the insulin… I was dropping again within the next 45 minutes.

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If I think the G6 is wrong I draw blood.

The G6 gives me a trend, I bolus off the trend not the number.

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I really like the G6, and I do understand the importance of using it for the trend and not the value. There’s plenty of times throughout the day that works out well. That’s why I put the picture in the thread… Tonight I actually thought the G6 was confirming what I had been anticipating… which was why I was tempted to just do the insulin. Turns out both the CGM and my instinct were overshooting what was happening.

Sorry, that wasn’t meant as a criticism; I replied off your post after responding to the original (eight day old) poll. The result was utterly out of context.

I do do broadly what you do; I only use the G6 as a trend, I only trust the reading if it is stable and is in the range 100-150 and not always even then. Otherwise I use all the other stuff I’ve developed over the years - how much I’ve eaten, how my muscles feel, whether I’m annoying the people around me and what the BG meter says.

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The fact you include that in your “measures” just shows you are a much more considerate person than I am. :grin:

And I didn’t take it as a criticism at all. I respond to everyone like that. Even when talking about sunshine and picnics. :grin: How do you like your G6? And have you used any others?

Combo answer. I would dose off of cgm data when I’d been fasting, sometimes, if it appears to be giving meaningful consistent data… but never in a million years would I do it for corrections.

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How do you like your G6? And have you used any others?

I gave up on an earlier model (the G4?); it woke me up repeatedly and failed after about 24 hours. They didn’t refund my money so I blacklisted Dexcom for a few years. The G6 is good, but remembering my previous experience still recreates a bad taste in my mouth so I won’t say more than that.
I’ve dropped calibrating the thing; it seemed to produce bad effects when done outside the 100-150 mg/dl range. I also just run it until it comes unstuck - xDrip+ has a “preemptive restart” option that avoids the PITA two hour wait period and I’ve yet to see any issues with running at least 20 days. Indeed, the first few days of a G6 seem less stable than the 20+ days, but that’s just a feeling.
It’s difficult to see how it could work in a closed loop without some mods. I’d trust it at 100+ with no significant up/down, but to use that closed loop means maintaining BG at 100+; I don’t want to do that.
I suspect eventually they will retune the CGMs to be accurate at 80-120 and require a closed loop.

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Hi all- I see that this post is from Feb '19 so it’s been awhile. Still want to ask this:
Is the G6 used for dosing decisions?

I’m wondering about the improvement of Dexcom G6 over the previous G4, G5 etc. models. I am under the impression that treatment decisions can be made using the G6. Isn’t that the G6 claim? that, it is real time, therefore no need for fingersticks? Having said that, if the G6 readings are very high or very low, I am likely to fingerstick. (Although for a low, I eat DexTabs first). The most useful aspect of the G6 is the trend and the graph, not just isolated fingerstick data points.

Do you find that the G6 readings are reliable if “horizontal” -> , or angled up? If it’s going straight up, I tend to wait and see what happens. I wait to see if it angles or becomes horizontal. That is I wait to see if the increase slows down and when the BG may have peaked. That’s when I take my correction insulin (usually a small amount). I have experienced two episodes of straight down arrow on the G6, together with the warning. (I’ve been wearing the G6 for less than 14 days). I am uneasy and become anxious and worried when I find G6 readings below 70 with warnings, alerts, straight down arrows; panic when I see 60 and it’s not horizontal If the reading is 70 and horizontal, I am ok. (One of the lows was caused by eating girl scout mint cookies with inverted sugar. The carbohydrates didn’t kick in until much much later. I’ll be careful about unusual ingredients.)

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I use the G6 for dosing, but only when I’m confident it is accurate. The first couple of days of a new sensor can be very noisy but I think presoaking a new sensor improves its accuracy on the first day - see my response in the G6 Newbie thread.

Other than that, yes, I’m on Loop which performs autoboluses based on the G6 readings without requiring any input from me. It has been working very well for me on non new sensor days.

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I routinely make treatment decisions using the G6 number. It works fine for me, because what could go wrong? If it says I’m high and rising I’ll take insulin and that’s right. If it says I’m high and falling I’ll look at IOB and guess whether I need more insulin or just wait.

If my insulin (or glucose) correction turns out to be wrong that just means I’ll eventually get a CGM alert that I’m going out of range, and I’ll fix it with glucose or insulin as needed.

I don’t trust a new sensor quite as much until it settles down and starts reading true, but even in that case I use its number to help me guess what my actual BG is, and use that guess to guide my corrections.

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I routinely use the CGM for dosing! But my son is on Loop so it’s making hundreds of decisions a day to dose based on the number…

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Same as @TiaG. When we see anomolies I do finger sticks…especially when the BG’s are shooting up very fast. The reason I’m most interested in upward fast spikes is because, as Tia indicated, loop is making hundreds of decisions based on the BG projection. IF that spike is incorrect, loop will give insulin and that can cause headaches in the hours ahead. So when he’s double up and I can’t think of a good reason it should be (i.e., he didn’t just eat), then I do a fingerstick and stop loop from giving additional insulin if he’s not really high. For instance, sometimes, for us, the CGM will read double up and go above 250 - hell even above 300…but a finger stick shows he’s only 130. In cases like these, even though he’s double up, I do a hard reset (enter BG twice) to stop loop from giving additional insulin. Sometimes doing that causes the message “enter BG number” in another 5 min and then I enter the number again do basically do a hard reset. It’s not ideal, but if we didn’t do this, Liam could be given 1 or more units incorrectly by loop that will most definitely cause us headaches.

But generally, outside of anomolies, yes we dose based off the CGM number via Loop.

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I am very unsophisticated and have a few questions:

Is Loop for those pumping only?

On my G6, I see only horizontal, angle up, angle down, and straight up or straight down. I don’t see double up, or double down. Am I missing something?

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You can learn more about loop here:https://loopkit.github.io/loopdocs/
And this is the FB group for the DIY Looped Group: https://www.facebook.com/groups/TheLoopedGroup

Currently you can build this loop rig if you pump with Omnipod or Medtronic and use a Dexcom CGM (spike is also supported with various branches).

I haven’t used our G5 receiver for a long while but they did have double up and down. I’ve just checked out the G6 user guide and it looks like they’re still there. They look like

image and image

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@ClaudnDaye Thank you for including the images; and pointing it out. I did not pick up on the subtlety.

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I do so and I do it without using a BG meter. I do so much more than my previous comments, or, indeed, actions, suggest; I’ve simply stopped testing with fingerpricks.

This is not praise of the G6, rather as a diabetic I have found that I can remove one inconvenience from my life (fingerpricks) without actually suffering serious injury; relying on the G6 allows me to live more of my life without actually terminating it.

My experience is that the G6 skips out. It will report a sudden drop in response to sudden temperature changes (showers, swimming pools) but it will also flake out, producing a drop of maybe 20-30 mg/dl which it corrects somwhat later. That said, if it has flat-lined for an hour (10 readings, 10 dots) then I have reasonable confidence it is within 20mg/dl or 20%, whichever is greater, of the correct reading. For the first time in a week I actually did a fingerstick and it said 126mg/dl. The G6 said 107.

I am not sure I am convinced of the angles any more. Typically I use my body; it reliably reports problems in ways I cannot ignore. I don’t check the G6 in the day; my body works, but I use it at night to because I OD on protein; the G6 alarms when it detects >180mg/dl at night. (It alarms once, sometimes I just ignore it and run high, I have to have a life.)

It’s a pesky backwards seeking individual. That’s a dropout; the transmitter has determined that the sensor is skewball and is trying to recalibrate it. The dropout takes 2 readings (10 minutes), the recovery takes about 3, maybe 4, so I expect to see a normal trend after 30 minutes. Do a fingerstick, that’s how I learned to deal with it. The way I look at it is that it is just a machine; I have to learn how it works, it certainly isn’t going to learn how I work.

I probably run myself high. I sometimes see the G6 below 80 when I know I’m not, I just ignore the damn thing. For me it does seem to meet the +/-20mg/dl requirement below 100 and I think my approach matches yours; indeed, if I see it say 60 I panic. If I see it say 70 downwards I expect to have already corrected because of a body report. Mostly this works out; my body says eat sugar, I don’t fingerstick, and the G6 backs me up.

I don’t know how to explain it except this way; it is a crude machine, it sort-of works, but add an enormous amount of human capacity to deal with complex stuff and it becomes something moderately valuable.

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3 T1D in house: we do bolus off G6 and many weeks only finger stick a few times or none. depends on day of sensor, how accurate it is, if any question we do manual BG. personally dexcom has been very accurate for all three of us and I have been using since first generation dex release many many years ago… I notice the only thing off for us is the lows usually, we are lower but that makes sense because dex reads off interstitial fluid and not whole blood so around 15 minutes behind.

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you should see double arrows if dopping high/low fast. I would call dex if not seeing these to be sure it isn’t an issue w/reciever

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