We are new to Dexcom G5 after switching from Enlite. When is the best time to start a new sensor and when will it ask for the first and next 12 hour calibration? Trying to time things so she’s not up in the middle of the night doing a calibration.
Is it also correct that if you are having inaccuracies, to test up to 3 times within a 45 minute period and if it’s still wonky change the sensor site?
I have the Dexcom g4, but they are both oh so vary similar. Sometime the Dexcom will be inaccurate, but there is a 20-20 rule, when the blood sugar is 80 or under the dexcom should be within 20 points of 80, so between 60-100 if blood sugar is 80, if it is over 80 then the rule is 20%, so times 90x.2= 72-108 range, if it is not within either of these rules I just re-calibrate and wait for it to catch up. You can calibrate before the 12 hour time period if you need to change the calibration times also, I’ve done it before. I hope this helps!
First of all, welcome to Dexcom! It’s a truly remarkable product and has changed our lives. We too had the Enlite but just couldn’t get it to work right for us. We tried everything and so did Medtronic but it wasn’t happening. Our experience with Dex has been the complete opposite. We typically start our sensors at night, though we’ve started at all different times. One thing that’s great is that it doesn’t really seem to matter when we calibrate or even if we go longer than 12 hours, as long as we do so when our daughter’s numbers are fairly steady and we don’t have rising or falling arrows. The advice given above is great and we use that rule too. One big difference we’ve noticed is that with Enlite when the numbers were way off calibration often made things worse, whereas with Dexcom calibration almost always seems to right the ship. With Enlite it seemed like once the sensor was way off it couldn’t and wouldn’t come back, whereas with Dexcom it almost always does. One note of caution: the first 24 hours of a new sensor can be a bit wonky so just wait it out until it becomes more accurate, which it always has for us. Also, we are getting 2 weeks out of one sensor, which is awesome, and we absolutely love remote monitoring. I hope you guys love Dexcom as much as we do and it helps you as much as it has helped us.
Thank you cdmccook! I feel better about when to calibrate! I wouldn’t trade the past 4 days with Dexcom for a single second with Enlite again. I will take one wonky day with Dexcom, vs months of inaccuracies with Enlite, any day.
One big difference we’ve noticed is that with Enlite when the numbers were way off calibration often made things worse, whereas with Dexcom calibration almost always seems to right the ship. With Enlite it seemed like once the sensor was way off it couldn’t and wouldn’t come back, whereas with Dexcom it almost always does.
People tend to talk about “calibration” problems as though everything else in the CGM is always copasetic and the source of the problem somehow results from the calibrations. I suggest that’s probably not the case.
All that is happening when a CGM system calibrates is some type of rudimentary “curve fitting”. If the underlying system performance is stable and linear enough, then calibration will help improve the accuracy of the system. The problems arise when folks attempt to calibrate when the CGM system has gone wonky and the underlying data you are trying to “fit” your calibration values to is wobbling around for reasons which have nothing to do with what your BG happens to be.
I believe this is the primary reason both Medtronic and Dexcom tend to discourage “over calibrating”. They talk about calibration as an indirect means to an end. It is easier to focus on the calibration than to explain to people the more tedious underlying system details which could be wonking out.
In a nutshell if your BG is relatively stable but the raw output from your sensor is jumping around, then trying to get the system to “come back” by calibrating is never going to work.
This can and does also happen with a Dexcom sensor, though anecdotally apparently more rarely. My impression is that when it happens people just (eventually) swap out the sensor and call Dexcom to get it replaced and it does not trouble them “too much”.
I suspect this has a lot to do with the different physical design of Dexcom versus Enlite CGM. The Enlite insertion site placement and sensor overtaping are finicky processes. I believe some people can just slap an Enlite on and have it work fine for them. Others, not so much. And a few others not only don’t mind the finicky techy tediousness but may even “enjoy” it to some extent. These folk can carefully feel their way through to get pretty much mostly good results with the Enlite.
I think my point is that while some people have truly horrendous results with Enlite that in itself does not indicate that Enlites are always bad and never work. One can get good results from using them. But, yes, if someone were to ask me for a recommendation I’d probably point them towards Dexcom. Mostly because if they then had problems I could pull out and play the “But everyone else raves about how great they are!” card. 
Hello!
I LOVE my Dexcom. Although I do have a few problems here and there, it is to be expected (I too experience the wonky initial 24 hours and am usually a nervous wreck when it comes time to insert a new one). BUT as a whole, the product works great and I would never go to another CGM. I typically as a rule of thumb calibrate at breakfast and dinner even if I had to do a correction calibration somewhere in between. The most I can get out of each sensor is 9-10 days. However, it is usually the adhesive that gives way first as I am a fitness instructor and sweat on the daily!
Yes, I was told the same about the 3 failed calibrations means toss the sensor. Thankfully Dexcom support is awesome about replacing sensors when needed.
Good luck with everything!
I too switched from the Enlite to the Dexcom G5 when it was released, and I am loving it! (I’m still under warranty for the Medtronic pump, and realistically would not be able to carry around yet another device at all times, so the smartphone compatibility was the deciding factor for me.) I know everyone reacts differently, but I’m finding that the Dexcom is extremely accurate for me.
What’s weird is that there doesn’t even seem to be much of a lag — I have always been told that fingersticks were the most up-to-date source of blood glucose info and to expect the CGM numbers to be about 30 minutes behind, which was certainly true with Medtronic sensors (and even when I’ve happened to remember what my fingerstick level was around the time I’ve had IV bloodwork). For whatever reason, though, with Dexcom it’s definitely not a 30-minute lag — maybe 10-15 minutes, at most, but I’ve probably had more instances where the fingerstick value was exactly the same as the current CGM value in the past month with Dexcom than in 3-4 years with Medtronic’s CGM system.
That’s interesting info re: calibration. It’s always been a mystery to me in terms of what works best, but with Dexcom, so far it doesn’t seem to matter when I calibrate. It’s always pretty accurate.
FWIW, I suspect the angular insertion makes a difference. I distinctly recall that the earlier iteration of Medtronic’s sensors, which were also inserted at an angle, were at times more accurate for me than the Enlites turned out to be. The problem, for me at least, was that you had to find the correct angle yourself and, suffice it to say, high school geometry was a long time ago and I do not own a protractor. Half the time, inserting those things ended up being a painful, bloody (literally) mess. And I was always running out of places to insert, because I was covered in black and blue marks from failed insertions. I had misgivings when I realized Dexcom had that same design — I worried I was going backwards — but, so far, I’ve barely felt the Dexcom going in. And I don’t have to worry about the angle, because the insertion device is designed to handle that.