@irrational_John, do you wear a Dexcom CGM? If you don’t feed it two consecutive calibration numbers at the end of the 2-hour startup period, the CGM will not display any reading. You could wait 15 minutes or an hour or two hours for the second number, but why?
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@irrational_John, @Terry4… I think that the two consecutive numbers back to back is not only ok–but necessary so that you can simply set a fairly confident start point. You are correct that there are intrinsic meter errors–so two checks are necessary so you can start off relatively accurate. I believe the system is designed so that as long as a good set point is made–it will be pretty accurate for at least 12 hrs. That’s my understanding at least.
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Hey Daisy. Simple answer is that I ignore it. I don’t do this often but have done it before. Has nothing to do with test strips etc. I just did it because I was on 3rd week of sensor and my numbers were running very close on Dex and meter.
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Nope, of course not. I thought I had mentioned that enough times in posts that it was known. But it’s also in the blurb in my profile pic.
Well, that is the first I have ever seen anyone mention this. And if it is true, it strikes me as a ridiculous way to go about things.
How exactly does the Dex startup work? At the end of the 2 hour period if you enter back to back calibrations then does it immediately displays a reading? There is no noticeable delay after the 2’nd calibration is entered?
And how does the comment from @Truenorth which I quoted fit into this?
Hi John - you are correct. After 2 hour warm up you must enter 2 readings and then you immediately start to see your numbers.
OK, if that’s how it works, then that’s how it works. Never mind.
My memory is not always the best when it comes to remembering all the details people mention. I should have clicked on your member icon; I now see that info is there.
If you read through the Dexcom G4 User Guide, chapter 7, you can see the description of how it works. In short, after the 2-hour startup period ends, the user is prompted to enter two BG readings. After the second one is entered, a number is displayed.
I’m not sure about the context of @truenorth’s quote. Dex customer service gave me similar advice when they told me how to correct large variations (inaccuracies) in the displayed number. Let’s say the CGM displays 250 and your fingersticks show 100. They recommend to enter three calibrations separated by 15 minutes. IN other words, calibrate at 0 minutes, 15 minutes, and 30 minutes. I’ve done this with success. I’ve never heard or read about doing this at the session initiation. Perhaps @truenorth has mixed up session start up with the context of large variation correction. Maybe s/he can provide better detail.
I’ll have to try this the first day @Terry4 when mine always runs low, may just solve that problem, hope so cuz once I get further into a session it is crazy accurate and I do wait days to calibrate as long as it’s on point as you all have suggested.
I was talking about session / new sensor initiation, but I have also used this approach (about 3 measurements spread out over about an hour) when the cgm seems to be be out of whack. In that case, if the method doesn’t work to bring the cgm back in line it usually seems to mean that the sensor is at the end of its useful life.
@truenorth, @irrational_John confused this to mean that upon completion of your 2-hour data blackout period, you would only enter one calibration number and then wait 15 minutes to enter the second one and then another 15 minutes to enter a third one. Is that what you understand and do?
If you do do that then after entering only one calibration at sensor start, you will not see any display for 15 minutes when you finally enter the second calibration. Is this what you do? Or do you enter the two calibrations back to back at start up and then follow-up with a third 15 minutes later?
I enter two straight away so I can see the cgm numbers. And I confess sometimes I just enter the same number twice at the start, rather than doing a separate finger stick-- if I know I’ll be entering a few more values in the hour ahead.
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Now I understand.
mikep,
when you ignore the cgm’s request for a blood drop/finger stick reading, does the cgm icon just go away after a while?
Daisy Mae
Yes and no, you push the enter button and the big red heart shrinks and goes up into the box next to BG number. It will keep reappearing every now and then you just keep pushing the enter (small circle button) until you decide the meter and Dex are getting “off” and you want to calibrate.
FWIW, I was also told by a Dex support rep to wait 15 minutes between the initial calibrations after I called complaining about the wild variations during the first 12 - 36 hours. My subsequent experience has found essentially no difference in the two methods. A new sensor is just gonna give some wacky readings until such time as it decides to settle down.
In addition, I know Dex has the 20/20 rule, but calibrating when the reading is …
… just seems wonky to me. When I have a CGM sensor reading of 62 and a fingerstick reading of 78, an error of over 25%, I am going to calibrate to that.
Using the Enlite system, I wouldn’t calibrate unless I was sure my bg’s weren’t moving in a direction that would indicate that in another 15-20 minutes the two readings may become equal or very close to equal. ie, the trend direction (based on 2 meter readings close apart–I’m not talking about trend arrows on the pump screen) would alert me to whether or not I needed to consider a calibration. Too often, in the past, I’ve been to fond of calibrating more than the recommended 2 to 3 times per day and that has sometimes cause the system to get confused. Not sure how that impacts (too many calibrations) the Dexcom.