Am I the only Dexcom user to have 7 days of great readings, but can't go beyond

day 9?

I either get “???” or the readings fall far, far below my actual bg on day 9. My wife can go 21+ days on hers and it stays accurate. She also had little trouble with the original Medtronic sensors, which didn’t work AT ALL for me. She had excellent results with the Enlites, while my success rate was about 1 in 10. Somehow my body seems “hostile” to CGM sensors. Anyone else have this issue, AND you know you aren’t putting your sensors into a scarred area?

You’d think if I got a full week (all the way from day one) of super accurate readings, that I’d be able to eek out another week, no?

The questions I have for you:

  1. How do you prepare your sensor site for insertion?
  2. Where do you put it?
  3. What do you use to protect the sensor from getting water on it?
  4. How long have you been a diabetic?

My son rarely goes beyond two weeks, and we often see irregularities in readings starting at day 10. He had one sensor that went 28 days, but that was an anomaly for him.

A long time ago I read the book “In Vivo Glucose Sensing”. What I remember to this day is that most sensors work extremely well in vitro. How well they work in your body depends on how hard your body fights the sensors. Think of allergies. People react very differently to pollen.


I believe dehydration combined with sensor age may also play a role here. Do you drink plenty of fluids every day? Coffee is a diuretic and can make dehydration worse. I have at times resolved the ??? status by drinking a few glasses of water.

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My experience is the same. I always extend past 7 days but it is a frustrating dance of getting ??? multiple times and debating when to pull the sensor. The g4 sensors represent a downgrade for me over the PLUS which I could count on to last 10 days and sometimes longer. I suspect your are right that it has to do with body chemistry and somehow the reformulated G4 sensor isn’t as good in my body chemistry.


I believe that Dexcom works very hard on making sensors fail after 7 days. Based on the performance of past sensor generations I believe that Dexcom could easily produce a sensor that would last 3 weeks for most people.


I have wondered that, too. I am apprehensive re the upcoming G6 that dexcom plans to last 10 days. Unless they reformulate the sensor, i wont be getting 10 reliable days

I am not concerned at all. I believe that Dexcom handicaps sensors so that the sensors fail early. Dexcom just needs to handicap the sensors a little bit less.

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The sensor is changed for the G6.

What do you think they do to do this?

How skinny are you? Sensors just don’t work as well in thinner people, and thinner people seem to have a harder time getting full use or extended use out of them. It seems like you need a good layer of fat for best results. Most of the folks I know with marathon sensor sessions (myself included) are not skinny and use their abdomens. I can use sensors for 3 weeks easily most of the time, so I don’t think Dexcom handicaps them, I just think there are a lot of physiological differences that can affect people’s results.

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We use to be able to use for a lot longer. Lately, we have been having the same issue. At some point, we thought that our transmitter was dying, but sadly replacing the transmitter did not solve it.


We have consistently received reliable sensor data for 12~13 days using the G4/G5 sensors.
I forget when we switched to the G4 - maybe in 2013.
BMI is average and sensor location is abdomen.

I have noticed sensors last less long now too. I also noticed a very wide range of sensor life in the early days of G4. It seemed to me that the very worst sensors that I was almost ready to toss and give up on in week 1 were the ones likely to work great in weeks 2 and 3 and last the longest. I have had a few last 4 weeks but normally I don’t try beyond 3 weeks.

Now that they don’t last as long I have far less problems in the first week and I only expect 2 trouble free weeks.


I also pull my sensor a day or two after a restart. It is not a cost issue for me but I would love to try and get a few weeks from one sensor. But usually day 8 or 9 the ??? and I figure why keep struggling with it and pull it. And I am also one of those who does get great numbers compatible meter but I still love my Dexcom and would not give it up. I just don’t dose from it and I pull it at day 8 most times. I do hope that the accuracy will be better for me with the AP’s that are in trials.

As others have pointed out, it would seem to be a very individual thing. Using only abdomen (a wee bit more fat than should be there) and arms (somewhat less fat than I’d like there), I’ve usually been able to go a few days past three weeks. The abdomen is longer-lasting, maybe because of more fat, maybe because of less movement. My current sensor has just made it to four weeks, a record for me. It’s on the abdomen, held in place with Opsite Flexifix (the same piece for three weeks), and I keep it dry it in the shower. Beyond that, I don’t know what I’m doing right.

what’s the "AP"s?

Mine is in the abdomen and 2 sensors went only to 9 days. My wife has hers in her arm and is on day 23 on counting. I thought about covering the site with a large waterproof dressing for showering, but isn’t that about a dollar per shower?

Artificial pancreas. There are a couple companies working on them. I’ve been watching the iLet with dual hormone.