CGM troubleshooting

My Drs don’t give me a lot of information or help with the CGM.

  1. Does your sensor usually last the full 6 days? Mine has been “dying” (won’t calibrate, always says my bg is plummeting when it’s perfectly fine.)
  2. Do you get reimbursed or credited somehow for sensors that don’t work properly?
  3. What do you do about showering/bathing? I always put a waterproof tape over my sensor and wear it that way for the full 6 days. But is it ok to remove the CGM for showers, and hook it up again after? Is it alright for the insertion site to get wet?

I feel like I’ve been “doing it wrong” to my own detriment (and debt!).
Experienced answers would be greatly appreciated! Thanks!

Which system ?

I can only guess this is a Medtronic question.

I think Medtronic sensors are 6 days.

I know Dexcom sensors are FDA approved for 7 days. But it is well known (including by the Dexcom CEO who actually seems fine with people doing it) that many people will simply STOP SENSOR and START SENSOR to keep the same sensor for as long as they think appropriate.

What cgm are you using? I have a dexcom and the sensor and transmitter stay on for showers. You can’t take the sensor out it would have to be replaced with a new one. I don’t cover it for showers. I put opsite flexfix under and over the sensor adhesive pad because it irritated me. If I have sensor issues dexcom sends me a new one. My sensors can last up to 3-4 weeks but I change them every week now because I ended up with expiring sensors. The expired ones do not work and tend to crash and burn.

We used an expired Dexcom sensor a couple weeks back. The numbers were useless. Typically the Dexcom (G5) is super accurate for us right out of the gate as soon as the warm up is over. This sensor session was just bad. Tried to keep calibrating for about a day and a half but it just wasn’t going to work. We stopped the session and threw it away. There was a little blood on the insertion. More than a “fingerstick” sized-drop but not enough to soak the sticky. I checked the sensor when it was removed and there was no dried/caked blood on it so it didn’t look like really bad from a blood/insert perspective. So hard to tell for sure if it was a bad insert or an expiration issue. In any event, I figured to play it safe and didn’t use any more from that expired batch as we had other Dexcom sensors that were current dated.

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For Dexcom,

  1. Absolutely. It generally lasts much longer. You are having issues with the calibration process, maybe? You do not want to enter EVERY BG that you take. You dont want to eat before calibrating. You want the data to be fairly stable when you calibrate.
  2. Yes, call them up and tell them you are sending them faulty sensors. I had a bunch break upfront. It was human error during insertion, but they still reimbursed me. You might ask someone to help you if your having trouble. It’s hard to see.
  3. Nope, nope, nope. Don’t take the transmitter off and put it back on after a shower. Its waterproof as long as the transmitter is in place. Otherwise, you are gambling.

Your right, Tim, probobly Medtronic.

I use the older model that lasts forever New one might not. I just mean that bad cali can lead to bad data readings. You remind me that taking tylenol is contraindicated and can produce goofy numbers. Just brainstorming, but it sounds like hardware failure…if she new to inserting sensors, check that its being done correctly. There are lots of online instruction videos.

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Yes, I’m almost sure I have a Medtronic sensor.

It’s actually important to first establish what sensor/transmitter you are using exactly – both the brand, but also the particular model. The second thing I would check is that the sensors are not expired – this has an immediate effect on their accuracy, unlike in the case of a lot of other diabetes products. So look at your box of the current sensors you are using.

(For the record, I am a satisfied Medtronic user and have been for more than 10 years and really detest the immediate assumption that since there are problems, it must be a Medtronic product. Their newer sensors are very good, unlike the ones the company used to make in the mid-2000s. There certainly are plenty of Dexcom issues one can also read about on the forums. Many factors come together to determine a singe user’s experience, not least the training they received, familiarity with their system and a worked out good routine for insertion and calibration. Rant over.)

Now, if you do find out you are using Medtronic Enlite, those last at least the full six days (the even newer Guardian3 last 7). If you have pieces that are dying, call the help line – often, but depending on what you have been doing and whether there is user error involved – the company will send you a free replacement if a sensor is not performing as expected despite your following all the instructions.

From my personal experience – I never disconnect the sensor when showering or swimming. I don’t even do overtape and that’s never been an issue. The sensor and transmitter, when properly connected, form a watertight seal. It is NOT OK to disconnect and expose the little metal pieces of the transmitter to moisture. On the other hand, I do bring my pump (which is my direct receiver of the sensor data) close to me in the bathroom so that I don’t lose the signal and have to recalibrate.

Here is what I would advise once you figure out what products you are using exactly:

  1. Find your user guide and make sure to follow all the steps for charging/storing, insertion and taping for your next change.
  2. Figure out the best time for initial calibration in your routine. (For me it is on a day when I have two hours as soon as I get up during which I am not going to consume anything.)
  3. Do not remove any piece for showering.
  4. If you still are experiencing major issues, call your local trainer. They are there to help you as well.
  5. If none of this has helped and your (non-expired) sensor still fails, call the main helpline to report and request a replacement.
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Some people tape over the sensor/transmitter site completely. I don’t do that as I believe it is important to allow the site to breath. No matter what, there will be moisture that will collect, whether from sweat or that will seep in during swimming of showers. I know that I can actually see the moisture in the adhesive part of the dexcom sensor after a shower. If your skin get’s exposed to water for too long it will just get icky. So I tape around the actual transmitter part, but I leave the transmitter and small sections of the adhesive patch exposed.

Sorry if my assumption was taken the wrong way.
My assumption that it was a Medtronic product was based from the OP when she mentioned 6 days rather then 7 days.

That was all.

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OK, my turn to apologize, @Tim35 . :slight_smile: My mini-rant wasn’t directly provoked by your comment above or even this thread as a whole. The automatic assumption I was objecting to was one I have encountered on this forum repeatedly and I guess I was primed to misinterpret what you were saying.

@T1_Japan – when you get a chance, do update us whether any of this advice helped. I hope so.

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Thanks to you all for sharing all this info!
I have a Medtronic Enlite sensor. That’s about all I know.
In Japan, all sensors come via the hospital, so I have no contact with the company. I wasn’t given a guide book or manual for it at all, the Dr just popped it on there, slapped some tape over it and Voila! I have a sensor…(anti climatic.)
My Endocrinologist did say that they have a lot of trouble with these sensors- they’re too sensitive to water and such.
I asked him about using the waterproof tape. At first he said it wasn’t necessary, then he changed his mind and said that the sensors are too sensitive, so I should use it.
I also keep my sensors in the refrigerator, because our home is only air conditioned in the room we are using at the time (Japanese style). So in the summer my bathroom area is a sauna. I was told these sensors can be easily damaged by temperature. Any one ever experience that?
I haven’t been reimbursed for my faulty sensors yet… I’ll have to ask about that at the next appt. there’s always so much to remember! My prego-brain is literally in full swing-I forget things all the time!

Japan’s diabetic care is really behind as far as availability to all the options. We don’t have any options. If I want a pump I have to go to the only hospital in my state where the Endocrinologist knows how to program them. There are two versions of the pump, both Medtronic. If I want to use the CGM, I get to have the Black Darth Vader pump. (Insert light saber sound effect!)
That’s about it!

OK, sorry about the disconnect between what I advised and your real situation. In this case, I think the best thing to do is learn as much as possible on your own so that you don’t have to rely on semi-helpful endos or anyone else. The good news is that there is this forum + all the English-language Medtronic user guides are online! (I would send you links, but they vary by exact equipment so you need to find them depending on whether your version of the Darth Vader pump – :smiley: they are all actually pretty fantastic pieces – is the 630, 640 or 670. That you should be able to find on the pump itself. Whether the transmitter is Guardian or Guardian3 is also something you can find on the back of the little grey “shell”.)

Also, here are some contacts that you might want to try on your own there too and ask whether you could get anyone to train you so that you can start feeling comfortable adjusting everything in the pump yourself and making the most of the system. (Not sure if you speak Japanese, which might be necessary.)
Medtronic Japan
Comodio Shiodome 5F,
2-14-1 Higashi-Shimbashi, Minato-ku,
Tokyo 105-0021,

Tel: +81-3-6430-2019
Fax: +81-3-6430-7110

The two below might be local representative/distributors, not sure:
Medtronic Japan Co., Ltd.
1-2-70 Konan, Minato-ku,
Tokyo Japan 108-0075
Shinagawa Season Terrace 22F
Tel: (+81) 3-6774-4611
Fax: (+81) 3-6774-4605

Medtronic Sofamor Danek, Co., Ltd.
7-20-1 Fukushima, Fukushima-ku,
Osaka-shi, Osaka Japan 553-0003
KM Nishi-Umeda Building 3F
Tel: (+81) 6-6453-3444
Fax: (+81) 6-6453-3464

I am actually a fairly proficient user of my Medtronic 670 + Guardian3 now (but was using the 630 + Enlite sensors until recently too) and am happy to chat directly with any more concrete questions you might have. (Credit for this should go to all my wonderful Medtronic trainers I have used through the years!)


Wow! This is an amazing amount do info! Thank
you so much for taking the time to communicate with me!

I would be cautious about putting sensors in the fridge, that might be worse. @Tim35, has commented about temp affect on devices.

I just looked it up. Surprisingly - the refrigerator is recommended to avoid high storage temperatures.

Enlite Sensor storage temperature range: +36 °F to +86 °F (+2 °C to +30°C)

“For temperatures greater than the recommended range, sensors will require cooled storage (such as in an ice chest or refrigerator) at temperatures not lower than the recommended range. Prior to using a sensor stored in a cool environment, allow the sensor package to warm up to room temperature for about 15 minutes before opening the sensor package to prevent condensation.
Warning: Do not freeze the sensor. Sensors should not be stored in direct sunlight, extreme temperatures, or humidity.”

And to stay “Fair and Balanced”, Dexcom has similar recommendations for their current sensors although they use a more limited temperature range of 36° F - 77° F along with a range of 15% - 85% relative humidity as well as also saying the refrigerator can be used for storage if required and also with the warning not to allow freezing of the sensor.

We have never done anything for our Dexcom Sensors (in the past 5 ~ 6 years) other than to stack them on a shelf in the closet. We do not have A/C. My thought on A/C - if the house is too hot then go outside. lol
Although I do relax (slightly) and allow heat for the house in the winter.

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Even when it is 42C outside?!!!