Starting G6 soon how do I calibrate it?

My App informed me I have three weeks left on my last G 5 transmitter so I will be switching to G6 soon. I talked about this over a year ago with my CDE and she said that you can still calibrate G6 but I have forgotten what she told me about how to do this.

Since Dexcom is so freaking inaccurate very frequently for me I am still going to be calibrating it and doing fingersticks as usual. Does anyone know how I do that? I have not seen CDE since Covid pandemic etc. I will have to either go in there or call her to figure it out if someone here can’t tell me how to do this. I’m having a phone call appointment with Endo on Monday but I’m pretty sure he doesn’t know how to do it probably, but I will ask.

What sort of an “answer” are you hoping to get? It’s hard to know how much detail to provide you without knowing more about how you intend to use your G6.

Will you be using G6 with an insulin pump (e.g. Tandem)? Will you be using the Dexcom receiver to interact with your G6 sensor? Or will you be using the Dexcom phone app to set up your G6?

Note: If you are going to use your phone, you should verify that the app will work on your phone by checking on the Dexcom compatibly web site.

Another Note: Even though you don’t need to, I would recommend entering the G6 sensor code to avoid requiring calibration. You can still calibrate it, but you’ll be able to do it on your own timeline. If you don’t enter the calibration code for a sensor then I believe you’ll be required to calibrate on the sensor’s schedule.

Yet Another Note: For whatever it’s worth, have you tried looking at any of the Dexcom G6 App Training Videos to see if they are any help to you?


I find the g6 very accurate. So much so I rarely ever even check it with a finger stick.

If you don’t get accurate results with it, then you shouldn’t use it. Try Medtronic maybe.

The whole reason I moved to the g6 was that I don’t need to calibrate.
I can put one in at bedtime and wake up with decent numbers no need to get up 2 hours later and calibrate.

I went from the G5 to the G6 early on in 2020 and have never calibrated, not even once. Is my CGM BG always identical to my finger stick, heck no but I just mentally adjust the difference on the first 24 hours of a new sensor as I am MDI and the have found that Dexcom products the more you calibrate, the more it messes with the algorithm so in the long run leads to more frustration and no better results. I used to soak my G5 but now don’t even soak the G6 as it is mostly accurate within ite limitations.

I calibrate rarely, but I do when I feel it’s necessary. I think I expect more of the G6 than many other people because my insulin automation is based on it.

Dexcom officially only wants you to calibrate if it’s more than 20% off your fingerstick or 20+ mg/dl off if your fingerstick is less than 80.

Those aren’t my rules, though. I don’t care much about accuracy with higher numbers, but I want them spot on under 100. If Dexcom says I’m under 70, but I feel good and the fingerstick says I’m in range… I’m gonna calibrate. Don’t screw with my data and don’t turn off my insulin!

  1. Make sure you’re using an accurate meter, not a random number generator.

  2. Only calibrate when you’re in range, because that’s when the fingerstick is most accurate. The margin of errors turn into bigger differences the higher your blood sugar is.

  3. Only calibrate when your trend is flat, and not if you’ve bolused or ate recently and expect the trend line to change. Glucose concentration changes more rapidly in the blood than the interstitial fluid that Dex measures, leaving a disparity between the two when your BG is changing.

  4. Also make sure you’re drinking your water. If you’re dehydrated, glucose can’t circulate through the interstitial fluid causing the data to be way off. Not a good time to calibrate.


What @Robyn_H said !! Right on. The G6 has been great for me using the code. When it’s off, be patient and calibrate only as needed to bring it back into decent accuracy. If one calibration does not get it settled in and accurate, I try to wait at least 12 hours before I calibrate again. I’ve never needed more than 2 calibrations, knock on wood.

Each G6 sensor will have a 4-digit code. When you insert/start new sensor, you will be prompted for code. This allows the sensor to not prompt for calibrations, and as some mentioned, results in accurate readings. But you can still enter calibration if needed, such as when a BG reading is far off and cgm trend is flat.

If you don’t enter the 4-digit code at start, you will be prompted to enter a calibration every 12 hours, which you can do, or ignore it.
If code is not entered, you will likely get less accurate readings at first, since the logic in dexcom uses that code specific to that batch of sensors.
But manual calibration after code can improve readings if they get off track.

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You’re kidding right- I have been using it for several years and will continue to but I knew I would prolly get idiotic answers such as yours. If you don’t have an answer to the actual question just don’t reply to my questions please! This site has become more ridiculous by the year, a sad occurrence considering how useful it used to be.

I don’t need replies telling me how great it is for you etc. waste of my time and yours.but thank you for indicating at least that you do still need to calibrate it and can. I guess it can’t be that great if you still need to.

Sorry but your answer is useless to me. I need to calibrate period and will continue to do it as long as it is possible whenever needed. I simply wanted an explanation of how to do this, lol. As I said dexcom is frequently grossly inaccurate for me and has been with each model. In the order of 50-200 points off. My endo has told me calibarte when needed.

Thanks! I remember now her telling me this, and thank you for actually answering my question😻 I will ask cde in advance to review it with her if possible. So I take it from what you are saying that it is still possible to calibrate even if I do enter the code? I had not heard that, she implied I had to not enter the code in order to be able to do it.

I am not sure what you mean by mentally calibrate? Lol.

The first few hours after a new sensor is inserted, my CGM can sometimes read BG up to 100 points higher than finger stick and sometimes they are quite close. I just dose insulin based on fingerstick and make a mental note of the difference, but do not calibrate CGM. Within a few hours, I take another fingerstick and find that finger stick is quite close to CGM so never calibrate CGM.

Since you seem so resistant to actual good advice, I will just say Happy New Year to you.

You did not answer the actual question, please read it before replying.

OK, sounds like what you are really looking for is:

  1. Press button on the front of the Dexcom receiver to turn it on.
  2. Tap on the 3 horizontal lines at the bottom left of the receiver screen.
  3. Tap 1 and then Tap 2 to unlock menu.
  4. Select Calibrate option in the menu.
  5. Enter the value you want to calibrate to.
  6. Tap save.

Happy New Year!!!

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Thanks you for this explanation which attempts to actually answer the question. I will review the links you provided. Hopefully the transition will not be too painful and I will figure it out.

I most likely will not be using dexcom on my tslim, but in the receiver for now and maybe the phone eventually. I have shut off the phone app due to stress from too many alarms. I turn it on when I start a new sensor in case my receiver fails. I will try the pump related insulin controls but most likely will not use them longterm due to too many gross inaccuracies with dexcom.

Thanks! Happy New Year😻

CJ114 gave the receiver instructions. If you do return to using the phone app, just tap the Settings icon and Calibrate is about half way down the long menu.

Personally I check against a test strip a couple of times in the first 24 hours, and often find I need to calibrate. After that, I only calibrate if I seem to be getting erratic results, and in that case I usually end up discarding the sensor and telling Dexcom it failed early – they always replace it.

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I think you are lashing out at the wrong people.
You call me idiotic, however you say you have been using the dexcom for a long time yet you don’t know how and when to calibrate it.
If you read the instructions it comes with, it tells you.
I was suggesting that I don’t need calibrations and that if yours is as far off as you say, then it’s not much use to you.
I hope that you can accept answers to your question without responding with insults and anger.
There are plenty of places to do that on the web.

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