Freestyle Libre question

Hello, I am Tom.
My question is about Freestyle Libre system. I am 75 and have been a type 1 for 23yrs. I have been using this CG monitor system since 2/19 very successfully and love it and learned much from it.
However I stopped it’s use two weeks ago thinking the sensor may be connected to recent health problems.
My experience is that when the sensor expires in the 14days, the needle has turned black and sometimes is distorted or collapsed. I wouldn’t think this would be any different from those using an insulin pump so I am asking if any others have had a similar experience with the needle.
I’ll share more later, but first would like to hear what others experience.
Thank you

Hi @Tomygun1. I was having an issue getting my Dexcom sensors refilled recently (someone messed up the paperwork for the first time in years!) so my endo let me try the Freestyle while they got things straightened out.
I used it for the full 2 weeks and didn’t see anything like you describe, and I’ve never had that with my Dexcom or pump insertions either. I hope you contacted them about the issue and sent it back. As I’m sure you know from all your years with diabetes, companies will usually send a replacement for a faulty item (at least if you wish to keep using it) and should want to investigate any issues. Wishing you the best in solving your mystery.

Thank you,
It turns out that the next to last sensor actually failed halfway through its use and I did call Abbott Labs and they did replace it. It wasn’t until two weeks later when I replaced the next one that it occurred to me that this can’t be right. I contacted them again and asked “is it normal for the needle to turn black” and was told that some blood must have gotten on it. I then asked “ is this unique to me?” And the answer was “yes”.

Sorry to hear you are having these problems Tom.

I used a Libre for a year and have since gone to Dexcom due to an insurance things and have never see this. I’ve had some sensors bleed, but nothing like this.

Sorry I couldn’t help. I hope you can find a resolution to this (if it is a problem).

Thanks for your input Drummin,
It seems I am experiencing something unusual, and I am trying to understand if metals are leaching from the needle causing illness, or if some unexplained illness is causing the needles to turn black. It’s somehow connected to my problem.
My doc and I coordinated many tests and the results only revealed that for a 75yr old type 1 I should be envied.
Still, while I feel better each day, I was very sick for two weeks.
I want to use the CG system again, but without an explanation I am afraid to return to it.
It is my hope that one of you can shed some light on what is happening.

I think the electrode is supposed to be made of gold or platinum, which are bio-inert.
The gold or platinum is coated with some type of enzyme that converts glucose into hydrogen peroxide. The hydrogen peroxide reacts with the gold or platinum and the sensor uses this to electrically detect blood glucose levels.
There is some kind of semi permiable barrier coating the gold, it allows glucose to get to the enzyme from the blood, but prevents the body’s immune system from attacking the enzyme.

Its possible that your body is somehow penetrating the barrier and destroying the enzyme inside, but your body will be unable to dissolve the gold or platinum inside.

Thanks for the information, that’s more than I have learned elsewhere. I was thinking the needle was stainless steel and that the nickel in it may be the culprit.
Still, something unusual is happening that not only turns it black but distorts and collapses it flat.

Hi Tom @Tomygun1, Welcome to the JDRF TypeOneNation Forum! Although what you have found with your Freestyle sensor sounds unique, I expect that you will receive good information from many people here who have much experience living with T1D.

If you haven’t done so yet, after discussing this unusual symptom with your doctor, you should report this to Abbott Freestyle so it can be included in its reporting - Freestyle might also be able to provide you with information.

On another point, your Libre sensor does NOT read and report blood glucose. Your sensor, like the sensors used in all invasive CGM sensors, analyses glucose levels in interstitial fluids - the watery stuff found between body cells. This difference will become obvious to you if / when you compare CGM [interstitial] readings with BGM [blood] readings and glucose readings obtained from a vein - differences are greater during BGL [Body Glucose Level] glucose level changes.

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Thanks Dennis,
I have and will continue to be in contact with Abbot Labs while trying to get to the bottom of this.
I do understand how the interstitial reading differs from a glucose reading and after the first month of use was able to adjust accordingly.
This CG monitor is a great aid and improvement over multiple finger sticks. I have learned just how erratic glucose levels can be between finger sticks, something I was previously not aware of. Adjustments to my insulin intake has resulted in maintaining my A1c in the normal range, so I hope to be able to resume using it.

Yes Tom, I’ve found the CG readings to be more consistent than the meter readings - and knowing that a meter can be considered accurate as long as readings are within the +/- 15% or 15 mg/dl range.
And I also pleasantly miss the minimum of 8 finger-sticks every day. I’ve used my CGM to increase my HbA1c about 0.5% while reducing my standard deviation and CV - in other words, more time in range and fewer wild swings.
Doctors are now advising older guys like us to have A1c closer to 6.5% rather than the 6.0% to avoid damage caused by increased hypo unawareness that comes with age. Today I have a double celebration - 78 years old and also 62 years with diabetes; spent my 16th birthday in and out of deep hyperglycemia induced sleep.

Hi Tom, I’ve been on the Libre since early 2018, and T1 30 yrs. I first tried the Medtronic CGM since I have always used the Medtronic pump. 24 hrs after inserting my first CGM I have an anaphylactic reaction to the wire inserted in me; turns out is it made of platinum, which my body was allergic to. Back to finger pricks every hour, then a friend alerted me to the new Libre, I called the company, talked to the technical dept., and ask specifically what the the inserted piece was made of. No needle, no wire coated in platinum, but plastic like my pump cannula. Overjoyed that I could wear a CGM, I tried it, no reaction and sooo happy to be able to wear one. Yes, the cannula piece is inserted with a needle, but the needle retracts after insertion back into the pod piece. It sounds to me like some blood got into it right after the needle inserted the piece. Maybe quicker insertion or location on your upper back arm? I wish you the very best!

Hi Patti, Thanks for sharing your experience with the CGM’s and especially about the different materials used in their construction. Like you, I had suspected that my body was reacting to something foreign but at least I didn’t go all the way into anaphylactic shock. But I became very sick with symptoms including chemical smell and taste, burning mouth, lips, and eyes, leading to nausea and headache. After 10days it slowly subsided and now only trace symptoms remain.
At present I still don’t have an explanation but hope to eliminate the possibility that my CGM was the cause. So I am back to finger sticks looking forward to being able to return to my CGM.

It’s very helpful learning the experience of others so I thank you for responding.