I have recently started on the Dexcom Seven Plus and have just changed out my first sensor. The first sensor was very comfortable and gave me 16 days of good readings, although the end was kinked after I pulled it. I have had the second sensor in for almost a day and I am getting some very odd trends (see the 6 hour trend picture). The general trend is tracking well, but the line is bouncing up and down every 20 or 30 minutes, which makes the directional arrows completely useless. I have the sensor placed in my abdomen, in line with my belly button and about 4 inches to the left. There is nothing touching the sensor, but my current theory is that it might be a bit too close to my belt line and standing and sitting may be causing the sensor wire to shift a bit. Has anyone had this type of trend before? Any advise would be apreciated. I called tech support for Dexcom and they weren’t sure what to make of it, I am going to download the sensor this evening and send them the data.
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Hey Chad, Welcome to the Dex!
I’m in a pretty similar situation I just started and had frustrations with my second sensor as well. See the link for my post asking basicaly the same question.
In my case it “worked itself out” meaning after a few days all was right in the end. I’ve noticed that my first day or two of data is usually an adjustment period and that the Trend Arrows during this time is as us pointed out, useless. But the overall data (visually observing the line) is still helpfull.
That being said I would work with dex and see if you can get a new sensor out of the deal, it worked for me!
Decaff
I’ve been using Dexcom Seven Plus for the past 4 months. I’ve found that I typically don’t worry about the readings I get until day two of a new sensor. 80% or so of the time, the first day’s readings are not particularly accurate. In fact, they can be all over the map. I try to do 4-6 calibration fingersticks during that first day, preferably just before any carb intake and a minimum of two hours after any previous carbs. By the following day, the Dexcom has calibrated and is quite accurate.
No matter what, though, never treat based on the Dexcom reading. ALWAYS do a finger stick before treating a high or a low.
I love my Dexcom, but I understand it’s limitations. I use it to monitor trends and as early detection of badly-guessed carb counting, either high or low, allowing me to make corrections earlier than I otherwise might have.
Cheers – Michael
I too have noticed this, usually when I am sleeping. My thought was that it occurred when I was tossing and turning or don’t sleep very well On the nights I get good rest, I get a more stable line. I don’t notice that mine have anything to do with a newer sensor, or even occur during the day, only at night. I would love to see what others think about this.
Michael,
I am not concerned about the accuracy, as the values have compared very well to fingersticks, my concern is the part about the trend not being a smooth, it is bouncing up and down by 20 to 40 mg/dl every 20 or 30 minutes. My first Dexcom sensor and the Medtronic sensors that I have used have always shown a much smoother trend. This means that it is showing that my BG is trending up quickly then down quickly, then back up, then back down. I am curious if anyone has experienced this and has an explanation or any advice. Should I try to ride it out and see if it will improve or just try to get Dexcom to replace the sensor and start fresh with a new sensor?
I’ve found that putting pressure on the sensor, when it has been calibrated without that pressure, throws off the readings. It’s important to avoid sleeping in a position where you’re putting pressure on the sensor as it’s been calibrated based on readings taken when you were not putting pressure on it.
My Dex will have weird times/days also, I have not ever figured out why so I guess it’s just me 
I to do not rely to much on day one, however, I insert a new sensor the night before and let it sit before beginning the sensor the next morning. It seems to help my day 1 be more stable and I miss only a night of readings. I will typically not calibrate if my sugars are swinging, and if my meter and dex is way off I wait until dex is reading a straight trend before calibrating the correct numbers in. I usually just wait the weirdness out. If you are not getting the ??? readings the dex usually settles in and hopefully will perform pretty good.
I am on day 3 now and I am pretty sure now that the oscillations are due to standing vs sitting, it seems to be calibrated very well to me standing and being active and as soon as I sit down at my desk or in my car it takes the dip and then comes back up when I get up. Yesterday I took the day off of work and went golfing with my dad and then played a vollyeball game in the evening and it tracked perfectly, whith no oscillations in BG trend, today I am back in the office, where I am changing between standing sitting very frequently and the trend is bouncing up and down again, I think that I am going to give up and change the sensor tonight.