This is really getting me down now

I really feel fed up.

My first sensor took 10 hours to start working then was great for 4 days and then started giving me loads of ??? for the next 3 days. It was fine if I kept still but as soon as I moved about, even walking upstairs, I would get ???

After 8 days I have replaced the sensor and this one started up after 2 hours and I got readings for approximately 20 minutes until it went to ???. It has been like it ever since.

Also the new site is really sore! Its only been in for 5 hours. I don’t want to take it out because I am in the UK and funding myself at £60 a sensor!!!

I feel like chucking the whole thing out to be honest.

What does anyone think?

The early sensor failure sounds anomalous, and you should call Dexcom about it. Talk to someone in support who can help you troubleshoot placement, storage, anything that might be interfering with the sensors, and then - hopefully - they can replace any defectives.

As for the sore site - I’ve found that if I place a sensor on my abdomen where I don’t have enough padding, ie the probe touches muscle, it’s mildly painful, but the aggravation adds up after a day and I wind up removing the sensor. It’s like walking around with a stone in your shoe.

Don’t toss it, yet. It is possible that you’ve got a box of bad sensors. You should call DexCom and explain your situation thoroughly. Escalate the issue beyond their standard call center - their management is fantastic.

Where are you putting your sensors? I’ve probably already asked you that, but I have no idea where/when I might have. The site should NOT be painful, which makes me wonder if your sensor placement is just not a good area (you need a spot with some fat!).

Let’s get to the bottom of the problem once and for all! :slight_smile:

I am putting the sensors in my abdomen, away from any pump sites and definitely in flabby bits.

I have called the Dexcom reps here in the UK and then they are calling Dexcom in the US i think. Because they have only been available here a few months, they are a small company - a third party i suppose - and don’t have that many people using them yet. It is also not helping that it is the Christmas period when things are not open.

I really can’t afford to be replacing sensors once a week. Or taking out ones that are uncomfortable. With pump sites i get them free in the NHS so i can take one out and throw it away and put a new one in. The Dex is not funded and is very expensive at £60 a sensor.

I completely understand (I paid out-of-pocket for my first year of CGM use). My first theory is that you’ve got a box of bad sensors. DexCom will replace them (and they might even give you a few free ones for your trouble).

But, you shouldn’t be dealing with pain either. My other theory is that the sensor is hitting a nerve or something, which will likely affect its transmissions to the receiver. I HIGHLY recommend that you try an alternative site for your sensors. When I used my abdomen, I used to get ???, too. Since switching to my upper buttocks, I’ve gotten amazing readings, and extended use (last sensor lasted 13 days!).

Also, I wonder how the extreme temperatures experienced during shipping affect the sensors. I remember when I first started on the Minimed CGM, the sensors had to be refrigerated. I wonder if the DexCom sensors are sensitive to cold . . .

Dee, I’ve found Dexcom to be extraordinary about replacing sensors that just don’t work. I was getting crummy readings from my last sensor and actually called them on day 5 of the sensor because my receiver reset itself. I mentioned that I’d been having sensor problems too and they pretty much just asked why I hadn’t called them earlier and told me they’d put a new sensor in the mail. I couldn’t believe how easy it was. I figured they’d blame me for poor calibration (medtronic has done this) but instead they admitted that sometimes a sensor doesn’t work and just sent a new one. They did reprimand me for not calling sooner about the sensor though. If you’ve got something that isn’t working right give them a call, they’ll try to work you through fixing it and if it won’t be fixed my experience says they’ll ship out a new one. I hope you figure it out, my Dexcom is the best thing that’s ever happened to my diabetes management when it works it really is a lifesaver!

+1 to everything you wrote!

Hi Shannon, and Dee.

Dexcom Sensors are ruined if frozen, but don’t mind a non-freezing chill at all. In fact, the storage life gets a little bit longer if you DO keep them in the fridge. But absolutely, positively, don’t fall below freezing. That’s why they label 34F as the minimum temp.

Rebecca (below) and Shannon are giving great, valuable advice here. Dexcom is DELIGHTED to replace a Sensor, regardless of whether it’s bad, mis-injected, or just unlucky (hitting a blood vessel). Just like Shannon, I never got good results by using a “frontal abs” location. For me, “love handles” work best (straight down from either armpit, an inch or two above my belt. It’s the best place for guys. Lots of women get great results there too, but upper butt cheek should be your first target: Not up high, where your pelvic bones are close against your skin, but lower, into a “meaty” location. I think it’s the best site for women; skinny young kids, too.

Just one more thing: I don’t know if Dexcom sells in UK with the same 30-day money-back offer which they make here. But if they do, keep your eye on the calendar: You want to be SURE to get it returned in time, if it doesn’t work out.

Dee, I’m sure this isn’t the problem but sometimes I forget and take a Tylenol or aspirin! That gives you ??? too.

No I am avoiding Tylenol (paracetamol) now. I was told that Ibuprofen is ok though.

Everyone here is being really helpful. My second sensor appears to be working ok apart from taking 10 hours to get going, the same as the first one!

I shall try the “love handles” area next time as I am currently using my butt for pump sites. My abdomen needs a rest!! I want to try upper arms too but they are a bit thin I think. I’ll try the “meaty areas” first.

Thanks again

regarding that business about provoking “???” when you move:

It sounds like you’ve got excess motion (between the wire and your SubQ tissue) when you move.

To reduce this motion, the first thing you should try is pre-wiping your target area (the whole area which will be under the pad) with Smith+Nephew “Skin Prep”. This is not the same thing as “I.V. Prep” – it’s made specifically for helping taped-down appliances to stay in place. It probably isn’t in stock at your typical drugstore/chemist’s shop. (The thin layer of adhesive helper also serves as a barrier between your skin and the Dexcom adhesive, reducing inflammation and itching.) Let it dry COMPLETELY before you set the Dexcom assembly in place

Next, you should press the Sensor housing VERY firmly into your skin after setting it in place, BEFORE shooting in the wire. You should also use your fingernail, or another narrow-but-not-too sharp tool, to press the adhesive fabric down too.

Don’t drag across the fabric, that causes damage. Just press fairly hard, starting at the edge of the transmitter housing. (Press down on the housing to keep your skin level during this step.) After pressing, move a 16th of an inch outwards, press again, and so on. Then go around to another area of the housing and work your way outwards again. Some people use fingernails for this. My fingernails aren’t long enough, and I have noticed that the “safety clip” is perfect for doing this-- take it off the “shooter” assembly, and use one of the 30-degree angled, rounded corners to do the pressing.

THEN shot the Sensor. When removing the “shooter”, try to keep the transmitter clip flat and motionless. Same with putting the Transmitter in and bending the lever to clip it into place. (And be absolutely sure that you’ve heard TWO separate clicks, it’s very easy to leave one side of the Transmitter loose.)

Finally, the last trick: To break off the Transmitter placement lever, use your thumb and index finger from one hand on the end of the two clips (not the middle “ridged” area which loosens the clips-- the very ends, next to the lever which you’re about to snap off. Squeezing your fingers together in this place holds the transmitter MORE tightly.) Now rotate the lever to snap it off, while using your two-fingered grip to keep the Transmitter housing and Sensor from twisting with the lever.

When circumstances force me to use only the “official” 2-hour warm-up period, my accuracy during the first 6-10 hours almost always sucks. If you eventually become able to predict how many days you get from “typical” Sensors (for me it’s about 15-16 days, then you have the option of inserting a new one and giving it a longer period of “pre-warmup” before moving the Transmitter and actually using it. Although I can get 15 days, I’ve taken to doing the switch on day 13 (day 14 at the latest), to make sure that I’m switching well before the old one becomes unreliable. This allows me to do the “pre-warmup” trick nearly every time.

BTW, that soreness you had was an almost certain indication of an unlucky site or bent wire. The wire was tearing/pressing/sliding at something sensitive, and that doesn’t happen within the calm, undisturbed, undifferentiated SubQ tissue where the Sensors work well.

I haven’t had any problems with ibuprofen or aspirin. I was told to avoid the Tylenol though!

I’m running 2 bad sensors for 12 good ones. I can live with that. One sensor never worked, and the other gave me the “failed sensor” after about 18 hours. I’m getting at least 2 weeks from each good sensor and the most accurate results come the second week. Animas haa always had a replacement to me 3rd day air with no questions asked. They’re great.

aspirin is NOT a problem. But anything using acetaminophen, either by itself (e.g. Tylenol) or within a combination of many ingredients (e.g. Excedrin) is absolutely forbidden.

I think i have figured out the problem, and it seems to be to do with the adhesive on the sensor. Once it starts to loosen a bit i start to get the ??? when i move around. The second sensor has lasted 8 days but today the adhesive started to give up and I’ve had the ??? again. The first sensor only lasted 5 days before it happened and now I remember that it was just after the sensor started to peel off.

It must be causing the sensor to move and the receiver can’t pick up the readings. When I sit still, it comes back to life after about an hour.

I’ll have to find a way to keep it stuck down for longer.


There are 2 actions that you can take:

  1. When you attach the sensor ensure good contact between skin and adhesive. I apply pressure with the back of my fingernail. With this technique the adhesive stays put sometimes for the entire wear time of 12 days.

  2. If the adhesive starts to peel off use some glue to ‘refurbish’ the adhesive. I use Mastisol. Search the forum for Mastisol and you will find tips on how to apply it.

Thanks RR, I am having much more success now that I have been making sure that the sensor is stuck to me well and truly. I was having lots of ??? because basically the adhesive was coming off and the sensor was moving about. I have managed to get my hands on some Skin Tac and Tegaderm patches in the last couple of days (not easy to track down in the UK - thank God for ebay!!) and I am on Day 8 of this current sensor. The last one went on for 10 days I think so at least I am getting a few extra days out of them.

I’m sorry I saw this so late. I’ve just joined the group! There were a few bad “Lots” of sensors that were sent out from Dexcom. I wasted two sensors in one of my Lots and called Tech Support. They replaced the two sensors and shipped Fed Ex to my house.

It was likely a bad “Lot” or box of sensors that you got.

Hope things are well now!