Replies to This Discussion

Permalink Reply by Michael McClure on December 18, 2012 at 12:18pm

What does "spot on" mean? You mean when the Dex matches whatever meter you own? I have taken blood from different fingers within moments of each other (specifically when the Dex asks for two BS when you are first calibrating a sensor) and had them be as much as 20 or 30 points apart. My point is, none of these devices is perfect -- not the Dex nor the One-Touch or whatever meter you use. A "20/25 point difference" doesn't seem remarkable to me at all when assuming that none of these things is perfectly grabbing your blood sugar levels.

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Permalink Reply by Mike on December 18, 2012 at 1:44pm

Exactly this. If a meter calibration number matches the Dexcom exactly that's just a coincidence and in no way means that they're both perfect at that point. I don't think I've ever had two startup meter numbers the same with a one touch and that's from basically the same drop of blood.

Permalink Reply by Clare on December 18, 2012 at 12:31pm

Where did you put this one ? Is it in a completely different spot than any of the others ? Those would be my first questions. According to the literature it only has to be within 15% of your blood glucose meter to be considered accurate whether it is high or low. So that can be a wide margin if you are at 200 mg/dl. on your glucometer, anywhere from 170 - 230 on the Dexcom would be considered accurate. I find it is a bit less accurate at the lower end of the spectrum.
I am likely to think a sensor is not going to work when I get the ??? or the hour glass indication more than once. Or it drops readings. I think you have been very lucky - or maybe spoiled by having spot on performance from day 1, most people find day 1 with any sensor pretty much sucks wind and it settles in after that. If it doesn't settle in by day 3 then I would get on the phone with Dexcom. They have been very responsive.

Permalink Reply by Black Llama on December 18, 2012 at 1:29pm

It's on my stomach as usual (same position, different side). I think I have just been spoiled by 2 really responsive sensors so far. I mean, the last 2 I worse were almost always within 3 to 4 points of any stick test. The one I have on now seems to be more towards the 15 to 20 point end of the spectrum. Maybe it will settle down. Still instead of a nice solid line like I usually get, I have a lot of jags on this one, where I've had to calibrate and it's been off by 20 points. Example. I ate, bolused earlier and the dex read 180. I felt higher than that, checked and my Freestyle had me at 204.

No dropped readings or ??? so I will stop being picky and keep on :D

Permalink Reply by Clare on December 18, 2012 at 3:38pm

OK so I re-read the marketing material I got about accuracy and the Dexcom G4. They count as "accurate" the % of readings within 20% of reference YSI when >80 mg/dl or within 20 mg/dl when < 80 mg/dl. So like I said, it seems to be less accurate the lower you go. YSI is the reference standard used to measure blood glucose.