I have been using my dexcom CGMS for about 2 months now and recently my readings are way off! It begins fine, with readings that are just above, right on, or just below my monitors. But within a day or so, it starts to give me alerts for readings that are not even close to what my monitor (and my body) feels. The worst is when it keeps me up with alarms all night long by tell me that I am "LOW" when I am in the mid-100s. Has anyone else experienced this? Is it a sensor problem? I will be calling tomorrow (due to memorial day) but I wanted to see if this is a problem that occurs quite a bit. I love my CGMS when it was working and just want to get back to that point.
I agree with Steve - with a qualifier: sometimes! I don't understand what makes the difference, but sometimes my CGM numbers are "right-on" and sometimes I experience what you are. On the days that my CGM is off, I do what Steve D talks about. BTW - my way off readings are usually on day one. After it settles down, I am usually good to go. Also, at night, if I really know I am good (meaning that I have been stable for a few hours) I will sometimes turn off the alarm - especially if I have to get a good night's sleep and function the next day! I know this isn't a great idea, but sometimes it is necessary. Good luck, and please let us know if Dex tells you anything different.
Is it just the one sensor, or a bunch of them? If it's the one, sounds like a sensor prob to me. If not, hopefully Dex will be able to give you some answers. Good luck.
Alice Rose, your use of the word "recently" seems to suggest you have experienced this with more than one sensor? Is that correct? Are you now using some different part of your body? If my sensor gets moved around and the wire in my body moves a lot, my readings can go bonkers. I try to avoid body parts and activities where that will happen. If you get moisture beneath the transmitter, that can also cause big problems. The tape holding your sensor in place must be in good shape. If the original sensor tape begins to loosen, I use paper tape from the drug store and place four strips around the sensor to hold the sensor in place very securely. I have a reaction to paper tape, so I have to use Skin-Prep and let it dry before using the paper tape. It really sticks tight and is water proof. It will hold a long time. My sensors usually are reasonably accurate for two weeks.
Alice are you doing a lot of exercising, when you start to see readings that are way off?? This happens to me sometimes i think because the exercise is causing much faster highs and lows, and then it helps for me to recalibrate more than just once a day..i stil measure 4 times a day, and i am always plugging these numbers into the dex..you should hook up with insulindependence.com in the arizona area, great group of athletes with diabetes..i am in the triabetes.org group and get some great information about managing diabetes while exercising
Thank you all for your suggestions and advice! I just talked to a Dexcom rep, who wasn't very helpful, He said that the device was doing its job if it was telling me I was low when I was low and high when I was high. I told him that the CGMS was registering me at "LOW" when I was only in the mid-70s and at 300+ when I was in the low to mid 200s. He then asked a lot of questions regarding where I put it and if I had been taking any sort of cold medicine. I brought up that I do exercise frequently and that I used my abdomen. At the end of the call, he said he would send me new sensors and that when my CGMS was really different from my finger sticks, I should calibrate it with 3 blood sugars, taken over 10 to 15 minute intervals.
So we shall see. This has been a problem over the last month or so, so I have experienced it with 3 different sensors. I have not used the CGMS this past week because I was getting so frustrated. I am going to wait for the new box of sensors before I try it again.
I too have had strange readings and outputs suggesting the sensor is off.
For me I have been immediatly getting out of my home - outside and 500 feet minimum and have found unit suddenly puts out proper in range readings consistent to caveman machine.
Do you have remote reading power meter/water meter in your condo/building. Some of these meters are operating in the 400mhz band.
What bugs me is that in quiet environments; I always get excellent readings and performance, in my car, out in open roads, out with jack rabbits in mohave.
Today, I have had these curious readings that are nonsnese and wildy off from the cave man machine that has been regularly consistent.
Twice now I have watched the reading climb to 193 and finger prick maschine at same time was decending and at 134 and 146. Once out of home either Big pine or in Camarillo, all goes back to working correctly proving nothing wrong with equipment except the uncrypted RF link that consistently runs in quiet environments without hair raising behaviour but in home is burning up my fingerprick strips, patience, time, good will and causing the heart stopping behaviour you describe.
I recently have had the same experience at night and I think it is related to when I lay on top of the transmitter. My receiver will freak out "LOW" and show a steady line with one outlier down in the teens. When I check my sugar, it is consistent with the previous steady line, so I re-calibrate, and go back to bed. I roll around a lot at night and have the transmitter on one hip or the other, if I get an outlier reading low it is always when I have rolled over in my sleep and ended up on the transmitter.
I also get many false lows at night. I ascribe this to pooling of the interstitial fluid at night around the sensor when one is not moving much. The interstitial fluid then get's depleted of glucose which creates the false low. As soon as I get up in the morning and start moving around the dexcom starts to read accurately again. Last night it beeped almost continuously, suggesting I was at 40 when in reality I was in the mid 80's. Eventually I just turned off the power since I was confident I had minimal insulin on board and would be stable for the balance of the night. These false lows at night are a real pain. My only observation in this regard is sensors located on more fatty tissue (like love handles) seems to work better at night than on the leaner front abdomen area.
I used to put my receiver on a table beside my bed. Every time I rolled over and my back was towards the receiver, the sensor could not communicate with it. I got crazy numbers. I had to start wearing the receiver clipped to my pajama pants, just below my navel. That way when I rolled over I was not laying in top of it.
I am having the same issues-- only on my second sensor. Wildly inaccurate. Saying I'm low, below 40 when I'm actually over 100. Saying I'm high, over 200 when I'm actually at 90. Jumping all over the place... keeping me up all night with erroneous alarms... Dexcom so far has been quite a disappointment for me. I really had high expectations, and my experience so far wouldn't have met even the lowest expectations. I'm happy for the people it works well for, but it's just not looking like I'll be one of them.
Sometimes Dexcom is reasonably close to the finger prick reading. However, several times a week Dexcom is over 100 points from the BG meter. Sometimes higher. Sometimes lower. Not only is this frustrating, it is very dangerous since I could be getting very low and not know it. Also, often when I enter a true BG reading into Dexcom so that it gets to where it should be, there is an ERR1 message. I wait the 1 hour and enter a new reading. Sometimes the ERR1 still comes up. I wait another 15-30 minutes and try again. If still ERR1, I put in a new sensor. That often ends up occurring in the evening so by the time the two-hour startup period ends, it is 1-2 hours past when I usually go to bed. During the 8 weeks or so I have used Dexcom, I had only two periods where a sensor was usable for seven days. I have been on the phone many times with Dexcom and they cannot tell me why the 100+ point discrepancies and/or the ERR1 messages.
dexuser -- That's certainly real disappointing. Sorry it's not working out for you. I've been with my Dex Seven+ since October of last year, so still a relative noob, and I am having the more common experience than yourself, it appears, where I get 10-20 days out of a sensor if I want (I often go ahead and change the sensor weekly just so I don't build up too much supply of them). I put them on my upper arm these days, and have only whacked one off on a doorway (Ugh!).
Additionally, most of my readings from my CGM are just fine for me. Most of the time my manual BGs are spot on with the CGM if I am trending flat. I do note differences when I am trending up and/or down, but this is to be expected with the 10-20 minute lag the Dex has vs. finger pricks. I know several folks here say to always (ALWAYS) manually test your BGs before making any sort of moves one way or the other (food and/or insulin), but I have found my Dex works as good as my One Touch Ultra for tracking my ups and downs, so I just roll with it. I have no issue injecting based on the readout from my CGM. But, I'm also the guy that uses one needle for my insulin injections until the numbers rub off (about 24 days or so, generally), so take that into accounting. YMMV.
Good luck sorting things out with Dexcom. I hope you can get it to work out for you. I found the Dex to offer me the single biggest change in my diabetes care in 30+ years. As a direct result of my Dex, my A1c is now at 5 (May 12). I've never ever been anywhere close to that -- my last couple of A1cs were 6.7 (Jan 12) and 6.5 (Sep 11).
