Numbers off after restarting G6 sensor

Your experience is mine as well and I never calibrate. I find if my BG’g mostly flatline for the 6 or so hours before inserting the transmitter into the new sensor my BG numbers are even better than you show, however, to guarantee the flatline, I need to be on an LFHC diet for those 6 hours. With a more varied diet, comes more variability and my numbers after inserting a transmitter into a new sensor are worse than yours but self-correct in about the same time frame.

I don’t think I could stand the repeated low alarms for 6 hours. Since I can’t turn off the 55-Low alarm on either my pump or phone, it drives me crazy. Sometimes I turn off my phone but I can’t turn off my pump. Pre-soaking helps me some but it doesn’t eliminate the problem.

When I think about the mental health challenges of diabetes, I think my biggest stressor is the first 24 hours of every new G6 sensor.

When I used G4 and G5, I usually restarted my sensor once or twice. I didn’t need to do it to save money. I did it to avoid Day 1’s. Unfortunately for me, a G6 restart doesn’t pick up the accuracy from the previous session. It reapplies the algorithm which makes my restarts read high so I am back to calibrating.

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I also prized the performance improvement in the second week after the first restart in the G4. It was easier to live with.


I too have crazy low readings in the first hours if I don’t do a pre-soak. If I do a pre-soak (usually 6 to 12 hours) then I never have crazy false low readings. Strongly recommend pre-soak!

Before I discovered pre-soaking, I tried to “calibrate out” the fake lows with calibrations during the first few hours. It’s pointless. The most common scenario was a seemingly infinite loop of calibrate, “sensor error”, “recalibrate after”, etc. The behavior in the first few hours has nothing to do with where the sensor will settle down after 6 hours or so. So I too fell into the “hardly ever calibrate” camp and never would calibrate until the sensor had settled down.

With the presoak I do not have the crazy false lows and usually don’t have to calibrate at all. I will occasionally cross-check with finger stick and occasionally after a couople consecutive cross-checks that are running high or low by more than 20 (all the same direction!) I will do a calibrate.

For example today, my pump has been showing near low all morning, 4.2-4.6 range. I am actually 10.2 right now. I try to calibrate and put in 10.2, it freaks out and tells me to calibrate again in 15 mins. I do that again, put in 10.2 again, it just tells me over and over to calibrate again in 15 mins.

This always happens! I can never seem to calibrate these sensors without them failing. I am literally calling Dexcom for almost every sensor I have going bad, soon they will probably think I’m trying to scam the system.

Many of us have found that trying to make large calibrations in a single step leads to exactly what you describe, @Sugarkryptonite. It confuses the algorithm. I won’t try to calibrate any larger than 30 mg/dL (1.7 mmol/L) at a time.

If you need to make a large calibration, doing it in two or even three steps will produce the desired effect and avoid confusing the algorithm. I usually allow about 15 minutes to elapse between calibration attempts.


@Sugarkryptonite Like @Terry4 has said, don’t attempt too large of adjustments at once. It doesn’t accept it well.

If it asks more than once for a calibration, the second time it asks, enter the calibration number, then you enter it a second time with the exact same number right away. That makes it usually stop and it will take that number.

I don’t recommend the method to just use unless you have to, because it has an algorithm it follows and that number will usually end up off. Where after a couple of “normal” calibrations it works it’s way towards the right number.

You might also want to change your site. I never had good results with the sensor on my abdomen. However I have very good results on the back of my arms.

Yeah I just ended up changing it. Actually I have good luck with back of my arms as well and that’s all I use normally but this one has been no good. Actually the past 3 :frowning:

It’s too bad Dexcom never used to ask what my transmitter ID was when asking for replacement sensors, but this past time I called they did…can’t really even use battery replacement transmitters anymore. Well actually I dealt with Tandem and they never cared, but now since December 1st all support is transferred to Dexcom directly.

I had given them another transmitter ID I had and actually used but I think I bought it from someone, and they told me it wasn’t the right ID as it was registered to someone else…they can tell through the Dexcom app on your phone. I deleted it now.

That’s why I refuse to use the Dexcom app or share my data with Dexcom in any way. Since I run my sensors for 3 sessions, I’ve always been terrified that they’ll notice a recurring pattern of using every sensor code 3 times.

But then again, all 4 sensors I have in the house right now have the same exact code, which was also the same code as the last one I used. I noticed it was the same as I was taking the picture, and went back to pick one with a different code (so I didn’t have to wait the 15 minutes)… And they’re all the same.

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Yup same for me. It’s unfortunate because I liked being able to see it on my Apple Watch. …trying to figure out a way around it. I gave them one of the new transmitter #'s I have and they didn’t say anything. It’s not paired to my phone yet because I’m not using it. I have Dexcom Share turned off on my phone so they don’t get any of that data. Also, they were asking me for my transmitter ID instead of looking at my account, so I’m guessing they can’t see that information.

I had similar experience when placing the sensor in my abdomen. Someone mentioned try moving it to my arm. Once I did that the accuracy in the first 8 hours was much better. No more “low” readings when my BG is actually in normal range.

If you haven’t tried the arm, you might give it a try.

I’d rather do your process, too, if it leads to good accuracy within 30 minutes.

I’ve read other threads about pre-soaking but I’ve never taken the plunge, so to speak. Do people generally cover the new sensor during the pre-soaking period – before the transmitter is inserted – with a bandage or something? Do they just leave it all hanging out? I’m worried about messing up my open sensor. To get a long pre-soak, I’d probably put it in right before going to bed the night before a sensor changeover.

Keep in mind that my Dexcom process works for me, your mileage may vary.

That’s what I do. I use an expired transmitter and click it in so that the sensor is protected. I then use my guitar pick to release it and replace it with the current active transmitter when the time comes.

The danger of leaving the sensor wire assembly unprotected is that the wire can break from repeated flexing. I’ve never had this happen, but I do sense that it is a risk. It’s easy enough for me to put in an old transmitter to protect the sensor wire. I mark the old transmitter with a sharpie pen to avoid mixing up the old and active transmitters.

Other people say that pre-soaking doesn’t help them, so be aware that this is not a guaranteed solution but still one worth trying for yourself.


I always change out my sensors at 10 days because I have not been successful re starting.

I’ve had crazy readings after insertions as well. It’s been more in the past few months than it was last year too. One sensor straightened out after 24 hours. The worst one was last one and when I took it off, I realized that it was bloody. I also read that if you use the skin protector wipes, to put it on the adhesive of the sensor and not your skin.

One day I am going to try to re start a sensor again and hope it works for me.

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@jean63 Just in case you do decide to restart, there is another way to restart. It’s easier if you wear it on your abdomen , it’s harder if it’s on your arm unless you have a helper.


Thanks Marie. I will try it again when this sensor expires. Last time, it wouldn’t re start for me. I followed these directions that you shared too. I don’t know what happened but I got some kind of error message and it wouldn’t re start.

@jean63 Just remember to follow the instruction with removal of the transmitter for at least 15 minutes or the new way of blocking it via the slot for 15 minutes. Old directions are still floating around with the old way of just restarting without removing the transmitter and that no longer works. The communication has to be broken some way.

I’m new to Dexcom and tried to remove the transmitter. Utter failure. :frowning:

However, using a thin test strip and forcing it over the contacts for 15 minutes worked for me!

Just need to make sure it’s really in there covering the sensor points and you wait the 15 minutes. I f you have an old transmitter and sensor, you can determine which test strip works best for you.

I have had luck with an alternate method.
If you un pair the current transmitter . Wait15 min. Then pair the same transmitter, you won’t have to remove it at all.

Then start the sensor as normal. I’ve heard mixed reviews. It works most of the time, but if the sensor is mostly used up, it won’t restart because the starting micro current is low.
I think this is an issue even if you remove the whole thing though