I admit it: I treat based on my G4 CGM alone

If you are not willing to use you CGM for dose correction will you use the AP? The current algorithm used in the adult version of the Dexcom G4 is the same one used in the AP. Which is supposed to be good enough to calculate and does insulin automatically via the AP.

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I use my G4 for corrections, using pretty much the same criteria as Dave26. Except I don’t always do as many meter checks as you. I have not had difficulties with over or undertreating. My Dex is not as accurate as some seem to be but it generally is lower than my Bayer meter so there is not much danger of over bolusing. If my Dex is high, I may ck meter as it will usually be about 30 to 40 points higher & will need more insulin.
I do another cheat that I would imagine no one else on TuD does. I only occasionally do two sticks for calibration. I just use the one number I get twice. Most of the time, though not always, when I randomly check with two sticks, they are within a few points of each other.


Totally agree with this statement. :smile:

I find that with some regularity, I do two fingersticks when I get a meter reading significantly different than the CGM. I frequently find that each hand is a bit different by 10-15%.

Back to the OP, I find that my CGM will sometimes read lower, sometimes higher than the meter. The biggest factor is when I go low it takes the interstitial fluid longer to catch up, but sometimes when I’m running a bit high, the same dealio. Likewise, if I calibrate and the CGM is higher than the meter, my CGM readings will almost always be higher throughout that 12 hour period.

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I’ve only had my Platinum G4 about a month, but can confess I have occasionally treated on the basis of a CGM reading without a finger stick, but very conservatively–e.g., enough of a correction to get a trending-high result to level off when a finger-stick is awkward (in the middle of a meeting, choir rehearsal or the like). I don’t seem to have quite the accuracy from mine that some are experiencing, though mostly it’s within 10-15 points of what my BG meter shows.

But you raised a newbie question for me: my G4 insists on a sensor change every 7 days–the software requires me to end the current sensor session and start a new one. Am I missing something obvious (entirely possible), or how are you (and others) extending that out? Do you just go through the “start a new sensor” routine without actually changing it?

Yes, exactly. Just restart without changing the sensor.

Thanks Lorraine. One of the biggest problems is how much “real estate” the sensor takes up, especially as I’ve recently had to switch to angled infusion sets due to problems with scar tissue and they use more space than the standard ones as well. Since you’re not supposed to locate the sets within 3 inches of the sensor, I feel like I’m spending a lot of time just figuring out where I CAN plant all this stuff whenever I have to move something to a new spot. If I can just leave one of 'em in the same place for a while longer it helps a lot.

Where are you placing DexCom? My son prefers his arms and legs for those sites.

Drifting from the original topic here, but nevertheless… I’ve been putting the sensor toward the sides of my abdomen, high enough to avoid contact with my belt. I wear a T-shirt at night and sleeping on the side with the sensor, though dis-recommended, doesn’t seem to be a problem.

I used to use the back of my upper arms, among other spots, as injection sites when I was on MDI, but getting the Dexcom inserted there seems pretty awkward though other people seem to be doing it. Even more awkward for infusion sets because of how they get inserted and the problem of where to run the tubing and all that. The angled sets use longer needles/canulas and I’ve had a much harder time finding spots that don’t hurt/bleed. In some ways life was simpler back when I was on MDI!

Doing arm sites by yourself is definitely awkward. Caleb loves using his legs. Maybe that’s a viable option.

the only location I get good results (Enlite) is on my right side, 3 inches or less above beltline, and 3 inches from exactly the right side of me. Any closer to my bellybutton and it’s a random number generator, or my precisely, a low ISIG generator much of the time. RIght now I am on day 5 and nearly every time I spot check the accuracy, it’s been within 10 points–usually 0-3 points. For Enlite that’s awesome. I’ve had 3 or 4 sensors do this, since decemember. would love it if every sensor was as reliable. It seems it’s all due to the precise location, rather than a fault in the sensor per se.

Yes, I rely on G4 CGM for the past 4 months with 100% success.
Psychologically it is a winner for me b/c it frees up my time.
Also I am D1 for 58 yrs: and do not have OCD!

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For the posters with cgm + arm problems. Don’t use the backside. I use the section of the upper arm thusly. Picture looking at arm just standing or sitting upright. The part between armpit and front of arm that faces forward. That quadrant is not slept on, by me, even as I sleep on my side. If you are a tummy sleeper, no problem either. Easy to insert. I insert with the plastic inserter pointing downward, not up. Easy to lift up after squeezing side things and it just falls out. After inserting the transmitter, I use my chin to hold it down while I twist off the little plastic stick used for the final transmitter insertion. Cover with Flexfilm and done for two weeks except for repair covers during the second week. Hard to describe but so easy to do.

At 44 minutes after posting, my message above is still not in the count on the home page where this thread shows. Still 32 posts vs the 33 it should be. weird or is someone reading posts b4 posting??

I have done it a few times to correct for a high, and to bolus for lunch, but I only did it at these times because I was out and about and (cough) didn’t bring my meter with me.

I have thought many times about doing it because I often feel lazy or annoyed with all the finger pricks. But I just get too worried about over treating, and just the fact of not knowing exactly what my BG is.

I do love my G4 and it is very accurate, but I still have times occasionally when it is too far off; and it’s in remembering those moments that leave me uncomfortable with treating off the CGM readings alone.

whats the most its ever been off?

It’s usually within 5 points of my meter, but sometimes can be as much as ten points off. Usually the only time I have trouble is when I insert a new sensor. Then for the first 4-8 hours after the startup time it can read as much as 100 points off! But once it gets it’s bearings, I’m good.

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