WOW is all I can say. The seven compared to the seven plus with accuracy and all. I am hooked. The first 3 days when it got wet showering it gave out for about 30 minutes but now it's adjusted I think. I have not gone swimming yet. Anyone go swimming without covering the sensor all together? How does that work out?

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I am using the seven plus... I've got a pool in the backyard and it's my source or exercise from June through October. I only swim about 30 minutes at a time. I do not cover my sensor at all. I just use skin-prep wipes after thorough cleaning with both soap/water and alcohol wipes. I routinely get 10 to 14 days out of one sensor. Even in the summer. In the winter I may get up to 20 days out of a sensor. YMMV of course. Apparently, my skin "takes" to the adhesives on both the Dex any my Omnipod.
Wow that is amazing. That would be awsome if I got that. Sofar I'm on day 6 and the sensor isn't showing any distress or missed readings. So when it expires you just shut it down and start it up again?
Yes. When it reaches "Sensor Stopped", don't even remove the Transmitter- just tell it to "Start New Sensor". After the mandatory 2-hour wait, you're good for 7 more days. But this is an Off-Label usage -- no one can officially recommend trying to do this. And if you push it too far, the readings might become undependable at THE WORST POSSIBLE MOMENT.

I can always get 16-19 days, but I never try: I stop at 14 days, while it's still pretty reliable. For me, that is. YMMV, IANAMD, IANON, and etc. (Your Mileage May Vary; I Am Not A MD; I Am Not A Nurse.)

I personally have terrible reactions to the adhesive, unless I use Skin-Prep wipes. ("Skin-Prep", not "I.V. Prep". The packaging is almost identical, so be sure.) For best results, Skin-Prep needs to be thoroughly dried before setting down the Sensor's adhesive pad. (Use a hair dryer.) With Skin-Prep? I'm as Happy as StaceyD!
Thank you. The reg 7 sensor always lasted me between 10 and 14 days and the adhesive was different bc it used to bother me and come up. This one does not. I'm very happy with it. The readings are about 4 to 5 pts from my glucometer so what more can I ask for. Even if I had to chenge it weekly my portion is only 50 dollars per box. Very very happy with it.
I have been using Dexcom7 for 17 months. I received a replacement three months ago. Although far from perfect, I have not had a hypo. reaction since I first began using. This has been terrific.
My last HA1c was 6.3.
Is there a better way to get my monitor to calibrate at the number I enter?
I would think if I calibrate my receiver at 130mg/dl it should register at this number.
I asked Dexcom about it not showing the BG I had just entered. They reminded me that the readings are behind fingersticks. There is some algorithm involved. I find that after I've calibrated it's usually more accurate (if it was off) about an hour later.
Interesting. I never calibrated twice within one hour.
I wonder if this is always the case. Have you re-tested a hour later enough to know, jrtpup?
I calibrate before breakfast, dinner, and bedtime. This is more than I'd prefer but I feel it is necessary.
I'm not familiar with the word, "algorithm." I'll look it up.
I don't recalibrate in another hour, I just find that the dex has 'caught up' to my fingersticks by then. I've retested a couple of times with a fingerstick in an hour, usually because I need to bolus for a meal or something. Often enough to make the connection :) Why do you calibrate so often? I only do once a day or if it's waaaaay off.
I meant to say fingersticks, not calibrate.
Dex recommends two calibrations per day. This proves nothing.
I feel as long as you have stuck your finger, you might as well calibrate. This is the easy part.
I just decided to do three because I hoped my receiver readings would be more accurate.
I would love to discover I'm wrong but I fear one time per day isn't enough.
Introductory Baggage:
The device of the last 2+ years, which newer people (and even Dexcom) are now calling the "Dexcom7" was previously named the "7+". I prefer to call it "Gen-3", to avoid confusion with the older model. When you call it "Gen-3", it's a bit more clear what you're talking about.
"Gen-2" was the original 7 day model, the first which could take a shower; and "Gen-1" was the 3-day system.
End of Introductory Baggage/

In "Gen-1" and "Gen-2", the "calibration curve" (which I believe to be a straight line) was calculated as the best linear fit for "bG-values-from-meter" versus "raw current" (Dexcom's ISIG, which we are not normally allowed to see... and from the one graph which I have seen, Dexcom made a very good decision in deciding to keep that data away from casual, non-scientist users.)

In Gen-1 and Gen-2, I had the impression that all readings were given "equal weight". In Gen-3, I think that a big improvement has been made to give newer readings more "weight" than older ones. So, the newest bG versus it's "raw data value" counts most, the second newest counts a little bit less, and so on. Even when you "Start Sensors", In think that Gen-3 continues to use some of the old history in creating a calibration "formula" to translate your raw data values. The calibration formula also involve factors about rising/falling bG. Gen-4, unfortunately delayed and then cancelled (at least in the USA), is reported to have had further improvements in these algorithms, as well as the ultra-critical logic for tossing out some of the data as "noise", too un-trustable to use in reporting a bG value.

(BTW, there is a fascinating report on Minimed's "noise" calculation, written by a University consultant of theirs, available on the web. Dexcom's advantage in catching lows quicker seems to be a result of less-optimal data management in the Minimed. Their next-gen will be better.) Anyway, here are my calibration suggestions:

(1) Don't perform just four calibrations in the first two days! The Sensor is new and strong, and it's also "breaking in", with a lot of unwanted variability. Give it a lot more meter readings to match against (calibrate at least 4-5 times on each of these days).

(2) Try to perform calibration over a RANGE of bG values. Here's an example: It's almost totally redundant information to give it your "two calibration readings" at meter values of 96 and 99, on day 5, 12 hours apart. You're teaching it nothing about the High and Low values you need it to
warn you about!

So push yourself down to about 80, on purpose. (SLOWLY, so that you're not falling dramatically through that figure, into a lower value.) Do a calibration there to teach it what a "somewhat low" figure looks like.

And push yourself up, with an unnecessary sugar tab or two, to a value around 120. (Use glucose, because it's genuinely DONE within a few minutes of "starting". You don't want to calibrate with an entire under-bolused meal in progress, because you can't be 100% sure when it reaches a peak value.) This give it a "moderately high" value to work with.

If you want to "draw the line", with the right slope, for a linear function, then you need at least two SEPARATE data points.

(3) Never enter a value below 70 mg/dL. When you've confirmed Hypo (at 70, 60, 50, or [[ yikes! ]] 40, or 30, you may be tempted to put the value into the Dexcom as a "calibration". DON'T DO IT!

The accuracy of Dexcom voltage/current as a "source of bG estimation" goes to heck at low values, and your fingerpoke meter accuracy begins to fall of as well. Combine these two numbers into a calibration adjustment, and you're going to get.... a "mountain of garbage" coming out. If you want Dexcom to be accurate with low readings, you're probably much better off letting Dexcom calibration match bG readings above 70 mg/dL against it's correspondingly higher, less noisy Sensor current figures, and letting it CALCULATE estimates for lower bG levels using formula it derived from those more reliable readings.

(4) ALWAYS be sure of your finger-poke technique. Garbage-In, Garbage-Out.

These are all guesses. I'm just an observer, with no access to Dexcom microcode, design documents, or study results. As a mere user, with no other relationship to the company, I can only view the Dexcom system devices as "Back Boxes" and theorize about what MIGHT be going on.

YMMV, of course. (Like, if you've using a YSI in your house, then your "bG meter" has no problems with accuracy at low readings ;)
Rick, thanks! Great info, makes perfect sense to me.
Powerful stuff, Rick.




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