G4 sensors fail at alarmingly high rate

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FlyfishermanNYC

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My first three boxes of sensors - 15 in all - so far 7 have failed to last 7 days. Mostly they fail within a few hours of the warm up period. Seems there is a quality issue here. Never had these problems with the 770G and the G3 sensors.
 
Welcome @FlyfishermanNYC 🙂 Have you managed to get new sensors from Dexcom? I didn’t realise people still used the G4. Could you look to upgrade or do you need the G4 for a reason?
 
I think these refer to Medtronic's sensors @Inka (confusing that they are called the same/similar things!)

Do you use any sort of skin prep @FlyfishermanNYC ? Like an alcohol swab, or something like SkinTac?

Are you contacting Medtronic for replacement sensors when they come loose earlier than expected? That would help them track data around any potential bad batches?

I think @SB2015 uses G4s, but I don't think she has mentioned a high failure rate.
 
Inka said:
Welcome @FlyfishermanNYC 🙂 Have you managed to get new sensors from Dexcom? I didn’t realise people still used the G4. Could you look to upgrade or do you need the G4 for a reason?
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These are Medtronics Gusrdian 4 sensors. I had been using the 770G system and Guardian 3 sensors for 7 years with no issues since switching to the 780G system this past April. As an engineer, RCA would indicate that what’s changed is the sensors and pump technology. 7 out of 15 sensors failing seems to me a poor job of testing and quality control. I am not the only experiencing this. Does Medtronics send free replacement sensors? Yes once the forms are filled out. Yesterday after 2 successive failures they finally agreed to send me a whole box of 5 new sensors - seem to me IMHO an implicit admission of a quality problem.
 
It certainly doesn’t sound very satisfactory, having so many fail @FlyfishermanNYC Apologies for misunderstanding re your sensor type. I’d only ever seen the Guardian sensors referred to as “Guardian” rather than “G”.
 
FlyfishermanNYC said:
Does Medtronics send free replacement sensors? Yes once the forms are filled out. Yesterday after 2 successive failures they finally agreed to send me a whole box of 5 new sensors - seem to me IMHO an implicit admission of a quality problem.
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I am using the guardian 4 sensors with a 780g pump.

Any problematic ones are always replaced by Medtronic. This can be done by calling them or through their app. As I use mine in a closed loop system I rely on it to work out and then have the pump deliver my insulin every 5 minutes in the background, so need a reliable sensor. I did have a run of bad ones a while ago, where they stopped before the 7 days was up but these were always replaced. I had one at the weekend where the insertion didn’t work and it could not get readings. I just put a new one in, knowing that I could get a replacement.

If the pump is any doubt about the readings it is getting from the sensors it will go into updating mode and ask me to check by doing a BG. It then has a think and decides whether it is happy that the SG readings are okay and then gets on with its job, or asks me to change the sensor (which Medtronic will then replace). Not perfect but very good. I get frustrated when I have to get involved, but only because I have got used to the HcL doing my thinking for me and I just being able to ignore it until the next time I want to eat something. Those interludes remind me of just how much the pump is doing for me.

Any questions happy to help. Also could be worth looking at the pinned link in pumping and tech for 780 users.

forum.diabetes.org.uk

780 Users

There have been quite a few posting that they are about to start or have recently started using the 780, so I thought it might be useful to gather our experiences together in one thread, so that we can support each other. Fire away with any questions about the system and finding workarounds for...
forum.diabetes.org.uk forum.diabetes.org.uk
 
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FlyfishermanNYC said:
My first three boxes of sensors - 15 in all - so far 7 have failed to last 7 days. Mostly they fail within a few hours of the warm up period. Seems there is a quality issue here. Never had these problems with the 770G and the G3 sensors.
Click to expand...
 
I was transferred to G7 earlier this year after being on G 6 for one year. My experience of failure rate with the G7 is about the same, and disappointingly high. Since last August I have had one complete failure to pair up, which I think may have been due to a slightly bent sensor ( when I removed it); and a couple of times when I got wildly erratic readings. This appeared to be a result of bleeding, visible on removal; one time when so much blood spurted out that I had to remove it anyway, and one when the ‘brief issue’ alert came up. This did resolve itself after 24 hours, but I got a false low alarm in the middle of the night when the sensor failed. A finger prick test revealed that I did not need the glucose I had hastily chewed, which was annoying. That is about 5 complete failures in 11 months and 1 partial failure. That seems to be a lot but maybe not percentage wise. I have not been able to find Dexcom’s own statistics.

I have to say that I have found Customer service quick to answer the phone , very courteous, and have always received a replacement very promptly. I receive the CGM sensors thanks to the NHS so I cannot complain. Yes, I wish the failure rate was lower, but I have ceased to think it was my fault.
On balance CGM is a great improvement. I think the challenges are not for the faint hearted though -not just the sensors but the connection to the tandem T slim I found quite hard to master, and have probably experienced every possible problem. Getting the sequence of changing the sensor and pairing it has to be just right.
I also have to remember to take twice the number of sensors with me that I may need when I go on holiday.
At the end of the day, I have my trusty finger prick kit to rely on - and that is what I had to use for 25 years so overall I can go with the inconvenience.
I would like to hear of other’s experiences with G7. I am 79 years old with rather wobbly skin on my arms, so maybe that does not help! And maybe I am not so quick to learn new technology as others.
 
Judith21 said:
I was transferred to G7 earlier this year after being on G 6 for one year.
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Sounds like you’re on the dexcom when this thread is about guardian cgm sensors? Maybe start your own dexcom thread?
 
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