New to Dexcom

I just received my Dexcom G5 yesterday. I bought the Bayer contour next meter last night after reading this was one of the most accurate. Anyone have any tips before I get started tonight? I feel a little overwhelmed with how it all works & figuring it out.

Have you watched the online tutorials? They’re very helpful! I did the G4 w/ Share, myself, as that’s the system I have, but it walks you through everything step-by-step. Literally everything from opening the box and NOT taking out your transmitter right off the bat, to how to start and end a sensor session. It took about 45 minutes to go through all the tutorials for the G4 system.

Dexcom also has roughly 1-hour long interactive webinars available where you can ask questions from one of their CDEs as they go through various topics.

I did the one for Clarity, since I was feeling fairly confident about the rest of the system after watching all the tutorials.

My one suggestion would be to start your sensor session at a time when it is going to be convenient to calibrate, and when you don’t think you’r BG is going to be zooming up and down. When I did my first one I was so eager to get going that I started as soon as the box arrived, which had it asking for my 2nd calibration at 3am - which so wasn’t going to happen. That put it off until I actually woke up closer to 6:45 am… at which point I have Dawn Phenomenon to deal with. Whups. In retrospect, knowing my body, with my second sensor I got it going at a time where it asks for my morning calibration when I’m normally more level.

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I got mine over a month ago. I did plenty of research before starting. Guess what I was still overwhelmed. Your not along there are great people here. Just jump in and try it. The issue I had was the initial day and half. When you start a sensor it was usually inaccurate, mine always reads low. So I started not to dwell on the numbers the first day. After that the sensor gets more accurate.


I suggest diabetes Danica and her method for placement ont he arm. I followed her along and I use it today to keep dexi on my arm


How is it going now that you’ve used it a few days? My son has been a user for seven years. He is currently 13. Please let us know if you have questions. We are happy to share our experiences!

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Hi Lexa,

I have been using Dexcom for over 3 years now, I do not see how I ever lived without it!

When I initially started using it, I checked my blood sugars almost every hour to see how my real blood glocuse compared to my Dex. I was amazed at how close the numbers were! I quickly learned that I MUST check my blood sugar B4 taking any action such as pump suspend or bolus. Even if the numbers always seem to match, sometimes they just don’t. Dexcom is a GREAT tool and will help you see how you are trending. It will show you arrows so that you know if your BS is rising or dropping (the most useful feature)! But again, the numbers do not always match. For example: My Dexcom was beeping at me before I got out of bed this morning, said I was 68. I checked my BG and it was 108. Make sure you calibrate it at least 2x a day, I calibrate mine probably 5 times a day, I am a micro manager!

Some advice:

  1. Start a new sensor at least 6 hours before you go to bed. It takes 2 hours to initialize, and this gives you time to ‘get a feel’ for how well it is keeping your numbers close to correct. Never start a sensor before going to bed you will not want to have to wake up and feed it blood sugar numbers!
  2. Keep it within range. I find that if I go out of range too many times it tends to throw the numbers off
  3. Medications, especially Tylenol will cause Dexcom to think your blood sugar is spiking. With Tylenol, I wait one hour, then check blood sugar and re calibrate.
  4. Do not be afraid to push the needle in when applying a new inset, I know it looks big and scary, but it’s just a tiny needle. Pinch some fat, push it in lightning fast. If you don’t do it fast you may bleed a little and it will hurt like heck.
  5. If the transmitter does not snap in with the little built in tab, snap it in by hand. Lately I have had a few where the transmitter snaps on one side but not the other.
  6. After applying wear a Tegaderm patch. This will prevent the sticky from getting damp in the shower, and it will prevent it from accidentally popping off (I have big dogs that jump on me, this is a must have) I use 4x4 size, I just use small scissors and cut a hole in the middle.)
  7. If your numbers are way off, check your blood sugar, feed it to Dexcom, wait 15 mins, and repeat
  8. Try not to use expired sensor sets there is something on those tips that lose efficiency

Those are some tips off the top of my head. I get the Tegaderm from Amazon. I usually wear my sensor until I start getting ??? marks or when my tegaderm is falling off me (about 1.5-2 weeks, I just stop and restart the sensor-not recommended but I do it - I am not made of $)

Hope this helps!
-code name trixie

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You might be seeing significant differences (such as the 68 versus 108) because you are calibrating too often. With the Dexcom CGM, more is usually not better. Calibrating too often can, counterintuitively, lead to less accurate readings.

You should calibrate only when the directional arrow is level (horizontal). Outside of two initial calibrations when starting a new sensor, doing two calibrations 15 minutes apart will not improve accuracy and may very well worsen it.

Thanks. I take tylenol on a daily basis and I think THAT is what throws it off. But hmm, maybe I will just leave it sit for a while…

Well good news for the future - Gen 6 is expected to eliminate acetaminophen interference.

I agree w @rgcainmd about calibrating. I find less is more. It’s not uncommon for Caleb to calibrate less than twice a day and that seems to help accuracy. I’ve found myself regretting overcallibrating - it usually results in less accuracy bc the difference at the time of calibration was interstitial delay, not inaccuracy.


And this is exactly why I will never get an integrated pump/CGM: because those clever folks at Dexcom keep coming out with ever-improving versions, which leaves you with an “old” version of the CGM that can’t be updated on your integrated pump!

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I actually talked to the head Dexcom developer about this because I was unsure myself. All calculations are held in the transmitter–so going out of range does not effect the accuracy. The receiver only has input when putting in a BG calibration.


You might want to search through the archives here. There have been lots of posts advising on the best methods for prolonging sensor life. These involve Skin Tac and Opsite Flexfix tape (or similar) to help stick down the sensors. They also discuss re-starting after the sensor stops after 7 days. Most of these discussions will concern the G4, but apply equally to the G5 (which differ only in transmitter connectivity).

Good luck


Thank you for the suggestion! I actually follow her and watched her videos on the arm placement. I think that’s where I’ll end up doing it. I used to wear my pump on my arms.

Thank you so much!!! I’m going to watch them today. I haven’t started yet because I had the flu. My numbers were all over so I figure it would be best to wait. What would be a good time to start a sensor?

Thank you for asking. I haven’t started yet. I was so sick for over a week so I decided to wait. I didn’t wanna start with messy numbers. I’m glad everyone is so helpful on here. It’s nice to finally have some help and advice after not having it for the past 10 years! Lol.

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Thank you so much for the helpful info! Yes it looks so intimidating & scary lol. I’m afraid it’ll hurt. I’m so used to my pump doing it quick for me. I’m going to start with my arm i think. I’m not sure where else I would put it since I’m a side sleeper.

The best time to start a sensor is:

A) At a time that’s convenient for you to do the 2 hour calibration. Starting a new sensor at 10pm isn’t optimal if you don’t normally stay up until midnight :wink:

B) When you can calibrate your first two readings when you would normally be at a general “flatline” or at least minimally moving up or down - so you don’t want to start a sensor at say, an hour before lunch, then eat lunch, and have to do the 2 finger-sticks right in the sharpest point of your post-meal rise.

C) At a time that’s convenient for you to do the next calibration 12 hours later.

I tend to do mine right about 1 hour after breakfast so that the 2 hour warmup period is ending at about the same time my Novolog is trailing off, and my blood glucose is running level between breakfast and lunch. I tend to get up around 7am, which then puts my calibrations around 8 or 9 am and 8 or 9pm. After the first 2-3 calibration cycles I’m not as worried about getting them exactly every 12 hours, and if I sleep in past when it wants one, or I’m busy watching a movie or something, oh well :slight_smile:

And yet, when I had a new sensor that was particularly inaccurate, a call to Dex tech support yielded that exact advice, “wait 15 minutes between calibrations.”

I should amend what I wrote to include not only “Outside of two initial calibrations when starting a new sensor” but also “during the first 24 hours of a new sensor”. Otherwise, my advice stands.

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Have you noticed that the first calibration adjusts the current reading kind of half way. If you then do a second calibration immediately with the same value, it will put the app on that value directly.