1st day on dexcom 4 - not going wel!

started my Dexcom 4 yesterday. can't seem to get it dialed in. looking for some answers from you guys!

watched the dexcom video, followed all the steps. waited the 2 hours to input my first 2 blood sugars. it hasn't been accurate yet! re-calibrated about 10 times in the last24 hours. even when I input a bs of say 150, after it recalibrates it immediately goes to different number, either higher or lower. there doesn't seem to be any pattern to it. it woke me up 3 times last night at the 55 low signal. took my bs in the middle of the night; nowhere near 55! bs were 145 and 96!

I've read that sometimes it can take a day or two for it to "settle in," but this seems really wrong.

and after taking a shower, I now have the dreaded ??? and don't know how to get it back to a bs reading. I input a new bs reading, but nothing happened.

I appreciate any and all help from you guys!

It can take some time to get more accurate. My first few days on it were a little discouraging as well. The ??? Will go away in an hour or so. If it doesn’t call Dexcom and they will give you a free sensor. Sometimes if you are dehydrated it will effect reading, or if you have taken acetaminophen. Give it some time, it can be a great tool. I have been without mine for a couple days because mine broke and I was awaiting my replacement and I have been absolutely lost

Day 1 was awful too. It turned out that only had 1 side of the transmitter clipped into the sensor. Did you double check this? Once this step was fixed, still had erratic BG readings. Decided to change the site and start over. That was the best decision. On occasion, there are bad sites that could be from hitting muscle tissue or other factors. You cannot enter a BG reading when you have ???. Usually the ??? resolves for us within an hour. Hang in there and keep trying. Soon you and your Dex will be in love. :)

Hey Gayle welcome and don't stress. The dexcom sensor usually takes a day or 2 to "marinate" . The dreaded ??? means the sensor is not communicating properly. If it happened right after a shower then there could be a problem with the transmitter not being seated firmly into the sensor which allows room for water to get in and mess with the signal. No amount of entering blood sugars will get it to come back online. You just have to be patient. You might just push down hard on the transmitter to see if it clicks in to place. I don't know where you put the sensor, but if it is the 1st day then my guess is you have it somewhere on your abdomen. The dexcom while accurate to give trends as to what direction your blood sugar is heading, is not super accurate to match exactly your meter. Mine in fact rarely matches my meter number exactly. On the first day of a sensor I always set my alerts to 300 and 60 because I know the thing will wake me up all night long otherwise with high or low alerts. Once it settles in though it is great for catching the highs and lows. Just be patient and give it some time to learn you.

My first week was great. Well except going into hypo shock 15 time in 72 hours, I think it was something reacting to me since I had a surgery the first day I started the dexcom system but I have to say it might have saved my life that weekend.

This week being my second week I have had the question marks 4 times. Today I have them and just slightly wiggled the transmitter and it came back, this was also after a shower. I think some water got between the sensor and the transmitter connections. I read somewhere that someone would use a blow dryer on low to remove water if it showed the ???.

I complained to dexcom and they are replacing the sensor so that’s good.

My unit seems to do the same on the calibration. If it’s at 110 and I enter 85 it goes to 93, but you have to remember it’s following an algorithm based on what it’s detecting and only reports back to the receiver every five minutes. But it still seems as acurate as my glucose meeter.

I have learned to be carefull with calibrations also. If I check on my meeter and it says 155 and I don’t feel like 155 I will test 2 more times to be sure. In some cases when this happened I was really 90 and 95 on the other 2 tests. So if I had out in 155 this would have messed up my reading on dexcom. At this point I trust it and don’t mind testing three times for a calibration, after all I don’t test as often now during the day. But the number you enter has to be a good number.

How old is your meeter, when’s the last time you did a control solution or replaced the batteries. Also be sure if it’s a code meter that it chad the correct code for the strips.

Are you putting the sensor on you abdomen?

Did you use anything like skin-tak when you put the sensor on?

It’s also important to let the alcohol dry completely from the transmitter when wiping it off before installing it onto the sensor.

Are you lean, if so are you feeling any kind of pinch when moving around?

Are you taking anything like Tylenol or something that may have Tylenol in it?

Are you on a pump, and if so is the infusion at least 3 inches from the sensor site?

You also want to stay away from scar tissue, this could include your favorite area for MDI shits over the years.

I have a chemical burn near the sensor (I left an adhesive dissolver on to long) and put neosporen on it. This was about 1 inch from the sensor. 20 minutes later I had the ??? So I think it was something in the neosporen and the fact it was so close to the sensor?

I think calibrating it to many times in the first day might confuse it more? But I also see users posting that the first day it’s a little off and gets better on the second day.

Dexcom does claim it’s allowed to be off %20 I think, this is also the percentage the FDA allows with glucose meeters (really irritating to allow this with today technology). But if the numbers are off more than 20 points you can call the 24 hours support and they might replace the sensor. Then you can remove that one and put a new one in.

You will find with experimentation that some sites work better than others. Boinking low at night when you aren't frequently is due to rolling over on the sensor while you sleep and also being a bit dehydrated.

Personally back of the upper arm works best for me, I can keep the same sensor functioning for around three weeks. It does take more calibration for the first day or two but does settle in.

I have had an occasional sensor the just did not work from the start, it usually was due sensor not inserted correctly, or the transmitter was not clipped in early.

Also I find that for me I have a consistent 10-15 mg difference in meter reading from left hand to right hand. If I alternate hands for calibration it can confuse the sensor readings.

A word of caution about the back of the arm. I was going to start a post for this but since you bright it up. I did try this with my second sensor at the start of week 2. I watched videos a dm read posts, made sure all my bases were covered. It turns out you really can’t tell how big an arm is in a YouTube video. For me, I loved having it on the arm in the beginning. But about 2 hours later I picked something up and felt a painful pinch in the arm. Even though I took the meatiest part of the back of my arm, I guess being lean and as a friend pointed out “toned” I managed to stab the muscle. I tried lifting up on it to free it but it just happened again and again. It lasted another 3 hours before I decided to take it out. When I looked and the sensor wire it was bent.

thanks for your quick responses! I'm just going to give it another day or two to see if it "settles" before calling dexcom. I already have my alarms set generously, 60 and 320, so it doesn't go off so much at first. but it was going off at the default 55 at night and waking me up when I'm not actually low. is there any to stop that loud alarm from going off?

by the way, the ??? went away, yay! and it finally matched my meter, another yay! maybe its finally "settled!"

but another question - I have my high alarm set to 320, but it didn't actually go off until it read 390??? yeah, I know, it's high, but I'm on vacation and just had a liqueor drink (Frangelico, yum!)

To stop the alarm you can change he profile to vibrate only.
For the 320 to 390 it may have been the second alarm depending on how fast you climbed. I found out the first night that the first alert is vibrate only, no sound. The second alert is vibrate followed my low sound 5 minutes later. Then repeated ever 5 minutes but the sound part gets louder.

One thing I try to keep in mind, the Dexcom is more of a glucose trend measurement rather than an exact level measurement. But take the advise of other here, and keep with it. It will get better.

One other thing to keep in mind is not to calibrate more often then the twice a day recommended unless the sensor is really off - I don't do it unless it is more than 30 percent or more and then I will only do a couple extra a day - let it settle in on its own. More frequent calibrations can throw it off. give it time to adjust - it could take a few days. Mine got more accurate the longer I used it. If it is still way off after 3 days or so call dex and they will replace it. Good luck - I had trouble at first too but a year into it I can't live without it and a1c down to 6.8 from 11 all thanks to the dex

A lot of calibrations in a day is not recommended, though I an frequently guilty of doing more than the recommended two, as well. One thing a Dexcom rep told me - if it's very off and won't get back on track, you can try doing 3 calibrations 10-15minutes apart. That overrides the algorithm to let it pay better attention to the entered calibrations - a sort of "reset".

Meanwhile, I also always find a lot of invalid fluctuation the first 12-24 hours after inserting a new sensor. After that, for me, it generally settles down and is an amazingly helpful and accurate tool.

Good info from everyone. I'd like to offer up my experiences, just so you can see a bit of a different perspective...

1. My G4 (and my old 7+ prior) never require(d) a 'settle in' period. I have seen lots of folks say it requires this break-in period, but that has not been my experience. It just works from the get-go, same as it ever does.

2. I use ONLY the outside of my bicep (right about the line of a t-shirt sleeve), and I go back and forth between arms with no issues whatsoever (no issues rolling over on it at night, or what have you).

3. I am currently out on short term disability due to dual back surgeries I had last month (fusion stuff), and I have now taken Tylenol, Vicodin and Percocet, all three of which contain acetaminophen. I have seen ZERO erratic behavior on my G4 (OTOH, my 7+ was all over the place when I took a Tylenol). Dexcom told me they have been working on this and were real glad to hear of my anecdotal success with acetaminophen products. She also told me that other folks may or may not have success with these meds -- right now it may be a bit hit and miss, until they are ready to say their system is 100% unaffected by acetaminophen.

4. As ScottD says, the Dexcom is following its own algorithm, thus it may or may not be exactly the same as your glucose meter. Just this morning my Dex said '141' and was asking for a calbration. My glucose meter read '139'. Damn close. Good enough for government work, as they say.

4b. As an addendum to #4, above, have you ever done repeated glucose readings with your meter, one right after the other, just to see if it's spot on? I have, and in my experience the multiple readings are NEVER exactly the same. Sometimes they can even be wildly divergent! Point being -- even meters can be off,

5. I dose off my Dexcom readings, though Dexcom says you should test before doing so (this is what I consider a CYA move on their part). But, they also say you can only use it when it is placed on your abdomen (because that was the only place the FDA had them test it, so another CYA move on their part).

I hope your experience turns positive soon. Sounds like it may be angling in that direction already.


Well, it seems that it's "settled in." didn't get woken up last night with false lows. it is more closely following my bs when compared to my glucose monitor, although it has still been anywhere from 5-50 points higher/lower. hoping to see it become more accurate as it "warms up." i've read alot of posts and it seems some people get very accurate results and others experience what i have this second day. time will tell, and maybe it will take experimenting with different sites too. thanks to everyone again for the encouragement!

Good to hear it’s getting more accurate for you. I hope your enjoying your vacation. I started to wonder about my own ??? After replying to you and decided to take the tar mister off while the sensor was still left on my body. Clean it with an alcohol wipe, let it dry and snap it back on. Turns out I have not had any ??? Since then and I didn’t have to restart the sensor.

P.S., I’m missing the California weather, I used to live in Cali for 15 years and recently moved to ohio for my job. But this last week has been single digests and it’s supposed to go -14 on Wednesday.

I have always had bad readings if I start the sensor immediately after insertion and then calibrate in the first 2 hours. I will usually insert new at bedtime and start in the morning or after about 6 hours of wait time. Then I’m pretty good to go. Easier for me than weird readings and I almost never get the ??? Unless I’m at the end of the sensor life after one to two restarts (2 plus weeks of use). Good luck!

thanks for the tip! i think i'll try this next time. i actually started my first sensor at around 4:30 pm, then calibrated at 6:30 pm, so that's probably why i had so many wacky numbers overnight!

I found that putting it on my arm yielded much better accuracy than my abdomen...not sure if that would help, but worth considering. Also, if you continue to have these problems, by all means call them to sleuth this out. I remember having some problems with my very first unit about 4 years ago, and struggled with it for too long before calling them. Within a couple weeks we figured it out that the transmitter was malfunctioning and I have never had anything nearly so frustrating since then. I am often amazed that the thing is as accurate as it is...sometimes within 0 to 2 points from meter value when calibrating...especially in week 2. I hope you can get things dialed in a bit...the device is truly a godsend for me.

things are going much better. although still struggling with showers and out of range.

have taken 3 showers since starting and every shower i get the ??? for at least an hour after. i ordered some flexifit tape and although it hasn't started peeling up yet, maybe that will help with showers?

i' a little disappointed with how easily it goes out of range. i though it would better range in my house than it does. my house isn't that big, but i can't go from my bedroom to the kitchen without it going out of range. any tips for that? i don't want to have to carry it around with me when i'm at home - i already wear a pump!

very handy to have while working out! no more having to leave the room to do a bs check (i'm still shy about it)! this morning i took a spin class, then yoga. was at about 115 when yoga started and was on a down arrow, so i lowered my basal 30% for an hour and kept it about 96 for the rest of the class. checked it against my meter when i got home and was within 3 points. now this is what i'm talking about!!!

what is a "tar mister"? and why did you take it off? Thanks!