Inaccurate blood sugar tests and Dexcom calibration

Sandy, the last I saw anyone post, Dexcom charges $325 for a box of 4 sensors. Keep in mind that most people get more than 7 days – that doesn’t mean you will though! They have had several programs going that you could get the system plus 4 sensors for about $1k. I just looked and American Diabetes Wholesale has it for $956.80 and sensors for $349.99. You can get them cheaper from them if you sign up for the auto ship program.

Call Dexcom and ask. They have different pricing if you pay cash instead of through insurance, and I would assume wholesale programs are still adding markup as well. When they thought my insurance expired, the bills sent for sensors was much less than what insurance was quoting.

I used to get an average of 14 days out of my Seven. I know the prices weren’t any cheaper for me back then for self pay but maybe they have changed it. I will call them and ask.

Ive been using the dexcom for about 6 months after Abbott sent me a check for my beloved Navigator. Ill try the suggestions of calibrating less. My expereince with Dexcom has been that the first 24 hours the accuracy is usually awful - often 40- 80 or more points off. It tends to improve by day 4 or 5 - Ironically day 8-10 are the best accuracy, after I restart the sensor.

Im not sure how the logic of less calibrations - to include ignoring the 12 hour calibration reminders, will help accuracy but Im willing to try it

Those of you that ignore the reminder every 12 hours to calibrate - does it keep reminding you or does it eventually go away ?

The Navigator would stop giving you numbers if you missed a calibration by too far. Which scientifically makes more sense than “calibrate less”

by the way - the dex is now showing the classic ??? and no data - looks like Ive had no data for 2 hours or so. New Sensor inserted today about 2 hours before the ???
What do you folks do when you get ??? - Ive tried calling support and the typical answer is " thats normal "

Keeps reminding.

RE: ??? - I have tried two things - 1) wait, most of the time the Dex tries to correct within the 3 hours, sometimes I will enter a calibration or even two after it clears the ??? and that seems to help, or
2) after the Dex has ??? me for over 2 to almost 3 hours, and especially if I think my sugar is stable, I go have gone ahead and put that number in as a calibration. Tech will not tell you to do this, but again, sometimes it seems to jump start the Dex and get it back in line.
This seems to do better at new, initial start up, not when sensor old and beginning to wear out.

This continues to be interesting comments.

Regarding handhelds; I would watchout for:

( ensuring clean techniques - fresh lancet, clean fingers I have found the following:

one touch for me on my body is badly water hydration sensitive, slightly dry and its readings off.

Standard test strips can be very sensitive to alternate sugars. Accuchek et all.

So far only strips reasonably consistent are free style FAD-GDH type test strips that target only human glucose and are oxygen insensitive. All other PQQ-GDH and normal oxyidase strips make big boo boos on my body unless I am eating solda crackers and water. I am fed up with FDA sitting on bum sucking lemons over this issue.

good luck.

I was just talking to my CDE about the inaccurate readings of the Dex, and her recommendation was different than what I’ve read in the past. She suggested only calibrating when my sugars are stable, and calibrating frequently. I asked how frequently, and her response was to enter in readings, if stable, whenever I checked with my monitor. I’ve only done this for a couple of days, and haven’t entered many, so I haven’t seen a huge change yet, but it does make sense. She said to never calibrate when your sugars are changing, i.e. after a meal, because the changes can occur to rapidly, and throw the CGM off. Does that make sense?

The frequency really doesn’t matter if it’s stable. The problem is that most of the time our sugars aren’t totally stable. If you put in one great calibration, and the number seem to match it consistently with more BGs, then there is no need to put in more calibrations, since it can’t get better. You can of course still test as often as you feel the need to, but adding more calibrations doesn’t add to the effectiveness. I try to aim for one very stable reading that’s not low - maybe 120 - 150.

It’s funny you mention this, because lately it’s been waking me up in the middle of the night saying I’m low at like a 40bg when I’m really in my 70’s… Grrrr…

Oh! Good info… Thanks!!! I will have to try that…

this is why the 20 % accuracy numbers are such a joke when chasing lows and when checking bg’s when under 100.

20 % accuracy is only useful on the highs.

i always periodically check especially at evening on low BG to see where dexcom is relative to finger sticks and enter new bg to ensure dexcom is close to finger stick especially when going to bed. this is where drift and offset is worse.

How do you get more than 7 days out of your Dexcom? Mine goes dead when it expires after 7 days

All you have to do is hit restart and it starts up like a new sensor. As long as you are using good tape and the adhesive is not pulling out, it should work OK.

I’m going through some of the same issues with this. I enjoy everyone’s comments, and appreciate everyone sharing.

One quesiton I do have though… Am I correct in assuming that even though you aren’t ‘calibrating’ the Dex very often, you still check your FSBS before meals and boluses? Right?

I do not. Once the Dexcom is dialed in (which typically takes 2-3 days) and reporting generally accurate results, I bolus for meals based on the Dexcom readings, and don’t take a fingerstick reading unless the Dexcom’s reported BG looks suspicious to me, or it’s time for one of the twice-daily calibrations. During the first couple days of a new Dexcom sensor, I check my BG 7-10 times a day; once the Dexcom is reporting reliable numbers, that drops to maybe 3-4 times a day.

I find the comments here surprising.

I find I need to do about 4 tests a day an dmore when the dexcom seems to be hovering too long on a value that should have changed…

Once in a blue moon even if - “accurate” does not cut it and in fact the 4 times a day keeps the Dexcom on target.and tracking good with handheld.

The joy of responsive interstitial tissue on small bodies.

Long as I am getting lots of exercise machine tracks better. Gut had the worst where the gut was miles off from the fingertips. Fingertips could be 240 while gut was humming along at 160.

I believe too many calibrations are counterproductive. I also calibrate only when stable.
But there are exceptions.
Last night, I did not have any food after 9 pm. I bolus-ed for food and for correction.
So at 1 am I was shocked to see double arrows up, at 270. This is when I expected to show arrow down. I knew the Dex was not correct. So I took a BG and it was 140. I entered it into Dex, while it showed 270 +double arrow up. Right then Dex changed to 168 and within one hour, it was at 90. This morning the Dex was 88 and my BG 89. Right on the money.
I had shown the Dex it’s Mischievousness, and showed it the right path.

yes, and too few are equally useless. That is why periodic timely checks and BG entry especially when Dexcom wrong helpful in keeping on track as sometimes error is cumulative.