Dexcom: what happens if you don't calibrate?

My first 2 G5’s are so accurate, I’m almost afraid to calibrate . :slight_smile: I suffered though a year or more with Enlites, so the accuracy of the G5 is quite a refreshing change for me.

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Then don’t, we frequently go 3-4 days between calibrations after the first day or two. We are getting very good results from the Dexcom system. Recently, we stopped trying to get the third week out of them, and are replacing all of them after 14 days. Due to lots of dropout issues in the 3rd week.


Chris, I asked tech support about what happens if I ignore the blood drop (reminder to calibrate). He said that for the next 4 hours, I’ll still get readings. It was my impression that he said it stops showing readings after that, but perhaps I’m mistaken. Could you clarify a bit, please?

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You’ll get readings forever! But when they lose their accuracy you need to calibrate.

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And we can often go a couple of days or more with at most 1 calibration every other day and the system stays very accurate for us. We don’t do it on purpose, it just happens btw.


I would agree with Dex Tech Support. You will get readings for the next 4 hours. And the 4 hrs after that. And the 4 hrs after that.
I know that Dex Tech Support is restricted from saying certain things which are not FDA approved. Their lines are recorded and am I sure they are fully aware that everything they say is subject to being analyzed later. For example, once the FDA approved (Dec 2016) of the bolus direct from the Dex without a fingerstick and I spoke with Dex Tech Support after that (on some other topic) they did tell me that they really appreciated the FDA approval because they knew for a fact that people were bolusing direct from Dex for quite some time but without the FDA approval, Dex Tech was NOT ALLOWED to even tell people when they SHOULD NOT bolus (like double arrows or really high or suspect numbers) because that would imply they were allowed to bolus under other circumstance. So they were effectively muzzled on what I think was really important information by the FDA. On the one hand I understand but on the other hand it is stupid. It is.

So with the G5, it is FDA approved for two calibrations per day. IMHO, Dex Tech Support likely is not allowed to tell you it is okay to run without the calibrations. That would be an FDA violation and possibly even get that particular Dex Tech Support guy fired on review of his phone call.

The reality is you can run the Dex forever with no calibrations required other than the initial startup calibration. All other calibrations are optional. With the exception there is a case where the Dex will stop giving numbers and require a calibration but that is more like an unusual error based on something it senses - not just time based like after 24 hrs or nothing like that.

However, that being said, I really don’t like to go more than 24 hrs without a calibration. Based on our recent discussion (different thread on Calibrations), I will try to get six calibrations within the first 48 hrs of sensor startup (counting initial double calibration as one because I think the initial double startup calibrations are averaged and used internally as a single calibration - my guess only). (No difference if new sensor or restarted sensor. Sensor startup is all new calibrations.) After those first six calibrations, if the cgm numbers look good (ie - when calibrating on a straight and level cgm with a good meter - Contour Next One - if the meter and cgm are within single digit of each other) then once per day is fine (for us). I like morning time right after waking up before the breakfast pre-bolus.


I sometimes go as long as a day or two without calibration—my average tends to be slightly under 1 calibration a day, excluding the first 24 hours on a new sensor when I try to be more careful. It’s usually within 15 mg/dL for me, often within 5-10. I’m always shocked that other people have to adhere to calibration schedules schedules so strictly but it really seems to vary widely by person. Do what works for you!

If I don’t calibrate, the receiver displays a blood drop that I have to dismiss before I can see my current glucose value. It’s pretty annoying to have to clear that screen over and over again when I want to look at the graph. Am I missing something that you guys are doing, so as not to be repeatedly nagged to do a calibration?

Most of us are not using the receiver, but a cellphone.

Trying to make me jealous, I see. j/k. Medicare has tied my hands. I hope they change that rule soon, but maybe they never will…

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Ah, sorry Dave, this must be one of the stupidest regulations I know.

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Nope. But when I am using the receiver and I know that blood drop is there, my finger is so used to the double tap that it is usually gone before I have it at eye level.

Yes - it nags. But it still displays the cgm. My guess is the touchscreen receiver may be more of a PITA to clear the nag. At least this, it is just a click that you don’t even have to look at it for.

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@dave - The Dexcom CEO has all but promised to take care of the situation one way or another. However he made it clear his first priority is getting the Dexcom system out to the people on Medicare and getting the reimbursements flowing back to Dexcom from Medicare.
Once that is done, he plans to work this issue.
If he can’t get it directly worked out, he has already said that he may bring back the “share” technology as a workaround.

Dexcom 2017 Q1 Earnings Call
May 2, 2017
Q: So, if I’m looking at the Noridian coverage decision from late March, the wording is pretty clear in there that you’ll only get coverage if you’re using the DexCom receiver to display data. And, in fact, I think in that document, the word only is capitalized and then it goes on to say that if a beneficiary uses a smartphone as the display device, the supply allowance will be non-covered by Medicare.

Kevin Sayer, CEO, Dexcom
A: [ clip ] And while we may sit here today with that position on the receiver being the durable part and being kind of like the centerpiece and the most important component of the system, we have a number of options here. We can certainly work with CMS over time to see we can move it to another category. We can also go back to what we did in the past with share and have the receiver talk to the phone. And we could – but certainly, we don’t have that product in our portfolio right now. But since we were the first to make it way back when we know how to do that, so we have a number of options here. We just need to let this play out. We need to get this technology on patients. We need them to explain how it has changed their lives and how beneficial it is. And we need to be pleased with where we are and not get too crazy. I don’t think that’s over time going to be a factor.

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@Thomas, nice find! Do you have a link?