Problems with New Dexcom

After reading many of your positive comments about Dexcom's accuracy and after wearing a rep's loaner for 2 weeks with excellent results (compared to my old Medtronic sensor worn at the same time), I bought the Dexcom. It worked great for 5 days. Then I had a meter reading 60 pts. different than the Dexcom. (I had been doing no exercise; just sitting at a desk.) Since the arrow was level, I decided to calibrate. 20 minutes later I got "???" I read the manual that indicated to wait up to 3 hours for it to self correct. I also called the help line and was told the same thing. For 2 1/2 hours there were no numbers, and then when they reappeared, they were way off for the next 18 hours (up to 100 pts) despite my calibrating several times. I removed the sensor and put on another which started off not too good either but is improving. Any ideas on what I may have done wrong?

(I posted this also on a different forum by error.)

It may have just been a bad sensor - sometimes that happens. I know you probably didn't, but sometimes if you calibrate too much it throws off the numbers too. Also, if you are on facebook, there is a great group called Dexcom that I have found very helpful too.

after nine months with it, I could not imagine my life without it.good luck and hang in there.

bad sensor maybe. sometimes it happens. I just rip it out after a couple off readings. Most of them work great.

It may be nothing. Give it some time and see if it starts working again soon. If still nothing in 24 hours, you have a bad sensor.

Bad sensors (or accidental bad sensor insertions) are fortunately rare. It does happen every now and then. I usually don't worry if a sensor is off from my meter in the first 24 hours after insertion. Within 2-4 calibrations, it's usually fine. And be sure to only calibrate when your BG isn't changing.

Also, I have much better luck with the sensor on the front of my leg/thigh, right around the bottom of jeans pocket level, instead of on my abdomen. If works really well.

Truly, I cannot imagine going without my Dexcom. I accidentally left it at home when I went on a recent trip, and I had a friend go pick it up and FedEx it to my hotel.

Hang in there -- it will work for you. And you're likely not doing anything wrong.

Make sure you stay hydrated as well, I get the ??? the most when I am dehydrated.

Thanks for your suggestion. I live where it is warm; so I try to drink a lot of water. However, I might not have done so that day.

I noticed, too, that the first day didn't have as good of numbers as the other days. It was that way with the Medtronic sensors as well. Perhaps my BS was changing. I didn't think it was and the arrow on the receiver was level when there had been readings.

Tech support told me to remove the sensor after I had 3 incidents of "???" in the next 12 hours. Too bad it went bad because there were 4 days worth of really good readings compared to my meter.

I, too, really like having a sensor to give me some idea what my BS is doing, especially since I'm hypoglycemic unaware. This morning I was 40, and thank goodness the Dexcom woke me up with an alarm. That's what I'm counting on. So it definitely did its job today.

Thanks for the encouragement.

Thanks for your advice. You are right. When I called tech support after having 3 "???" in 12 hours, I was told to remove the sensor and put in a new one. I just hate to pay $100 for a sensor and have it go bad so quickly. Thank goodness Dexcom sent me another.

Today the new sensor worked great, waking me up when my BS was 40 and dropping. That's why I have it. I was happy it alarmed me.

I hope they sent you another one at no cost. if not, you should tell them to - they are fairly good about sending stuff out when it goes bad.

Thanks for responding. I did leave it in for another 12 hours, hoping it would self-correct. However, after getting more weird numbers with 3 more "???", I called tech support and was told to remove the sensor and put in a new one. The new one is working great so far, alarming me to a low BS while sleeping. Thank goodness it worked.

Thanks for your input. Evidently, it was bad as Dexcom advised me to replace it. I did and the new sensor is working quite well so far. (Knock on wood.)

I'll look on Facebook. I appreciate your letting me know about this.

Yes, no charge, and I received it the next day. I was happy with the service. I just wanted the sensor to last longer than 5 days, especially since it was my first sensor and it had been reading so well for the first few days.

I have had sensors go bad (very rarely) and Dexcom is great about replacing them. Experiment with different sensor locations too. We are all different so some of us have better luck with different areas. I have better luck with the sensors on my arms. Hang in there. Soon you will be lost without it.

Thanks for your advice. I will keep working with the Dexcom as I really want and need it to work. The new sensor has been working pretty well so far. Hope it remains so.