Freestyle Libre needle/filament too big?

I know there’s another current thread on Libre but a little long at 75+ replies.
We had hopes for this product but they didn’t materialize. For a child it really comes down to the size of the part that you keep inserted (i.e. the pain factor), which is precisely why that information is hidden from the product’s description and the phone reps, once you understand their english, have no information on either (they just read from the website and refer you back to it, as they’re there to collect you name/data for the company). I eventually got a supervisor on and found out that the size of the “filament” is 5mm long x 0.4mm thick. For keeping it inserted in your flesh for hours or days, that is a big piece of metal, like walking around with a syringe in your arm. Even our pen needles are 4mm long x 0.2mm thick! Our wait for a decent product will have to continue unfortunately. Anyone knows where’s the long-promised google-dexcom cgm at? Thanks.

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Just to be clear are you assuming that it is too large to be comfortable or are you getting complaints from your child that it is uncomfortable? A lot of people are afraid of using steel needle sets for Infusion such as Sure-T’s as opposed to cannulas but for many of us the needles are very comfortable and are in fact much thinner than cannulas. In other words, preconceived notions about how comfortable something will be doesn’t always match up with the reality of using that item


Would you be able to elaborate as to what you are inquiring about?

Dave, I am assuming, based on the described physical size and on the experience of using our pens. (Of course that pump cannulas are way bigger - so hope we’ll never go there). The Libre’s needle/filament is more than double the inserted volume of the pen needle. For some adults it might be acceptable but not as a constant wear for a child with low pain tolerance, I think.


Tim, I remember 1 year ago that Dexcom made some forward-looking announcements about their next generation using a much finer needle, and requiring less or no calibrations. I thought it was supposed to be out by now. I also thought they were in partnership with Google on this or another cgm with minimal pricking. Sorry I’m not being more specific. By the way, I also thought that Apple was working on a minimally-invasive cgm, for quite a while now.

Got it.
I do not think Google is involved. EDIT: As I read Terry’s post - I agree. Verily is linked with Google. The Verily device will come after the G6.

It sounds like you are speaking of the Dexcom G6. This is expected to be launched in 2018.

This will have a different insertion device then the ones we are all used to. The G6 will launch either as one calibration per day or no calibrations per day. Dexcom is working with the FDA to decide the best approach. Dexcom has stated they intend for the G6 to be available as no calibration before the end of 2018. However they could launch earlier in 2018 as once per day calibration and then get an FDA approval update to switch to no calibrations. That is still up in the air.

In terms of the needle size, I do NOT recall any conversation about that. The big thing about the G6 insertion device is that it is a single button push and much much faster and less clumsy. I can not speak either way regarding needle size. I have simply not seen that come up as a point of discussion.

Current G5 insertion device as compared to the newer G6 insertion device.
(G6 not yet approved or launched)



Dexcom announced a while back that it was collaborating with Verily, a division of Alphabet, the parent company of Google. Here’s some info as published in mobi health news on March 1st of this year:

DexCom’s partnership with Verily is aiming to produce a tiny dime-sized CGM that requires no calibration and can be marketed to people with both type 1 and type 2 diabetes. Because that platform is based on G6 sensor technology, Sayers said, it can’t launch until after the G6. The company is anticipating that the first product to come out of that partnership will be commercialized by the end of 2018, with a second generation due out in 2020.

“We continue to conduct human pilot studies with first-generation device and we have completed our initial feasibility studies for the secondarily Verily product and remain excited about continued progress on our collaboration this year,” Sayer said.

Not sure why you put “filament” in quotes in your original message. That is exactly what stays inserted in the body and NOT at all “a big piece of metal”. The needle (barely perceptible during the seconds of insertion) gets retracted into the insertion pod. Granted, I am an adult, but I do find the Freestyle Libre flash monitor to be super comfortable and painless to the point where you forget it’s on your arm. (See more about my first experience with this sensor here: FreeStyle Libre Flash Glucose Monitoring System)

For a perspective closer to that of an actual child wearing it, see here:

I say give your child a chance to try it. It might indeed not be the right choice for him/her, for reasons of size or other considerations, but you can’t know in advance. And more likely than not, your child will love it.

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I can’t speak to the perceptions of pain in a child but I find that the filament size that remains with my Dexcom sensor does not usually create any sustained pain. If it is painful, I find a high correlation to nicking a blood vessel and I will withdraw it. Blood fouls the sensor and makes accurate readings difficult or impossible.

Have you tried a numbing cream to help with any insertion pain? I suspect in a child that it is hard to discern between psychological pain and physical pain. They’re both very real.

Good luck sorting this out. You’re right about finding the actual size of the sensor filament that remains. I couldn’t find any dimensions. Dexcom has described their filament as the size of an eyelash. I agree with this comparison.

You raise an interesting issue. I’ve been curious about the Libre and assumed its filament was very thin, much like Dexcom. The pix with the blog post linked below tell a different story. It looks to be about the thickness of a pump infusion set:


First off, as always, you parents of us type 1 children are God’s gift to us! Love everything you do and think and fight for everyday!
I have just a few ideas and thoughts here. First I suggest asking your child’s doctor if they can get a sample. Many companies allow doctor offices to let patients use the product for a trial run. It can’t hurt to ask. The worst thing that could happen is they say no. Other option is to ask Abbott if they can send you one to try.
The other thing to think about is speed. I know how hard it is to wait for the next great fix! I have been waiting for 47 years for that promised cured. And I have been waiting for years for the artificial pancreas and still waiting. But wow have things changed over the years. I mean think about us testing our urine 4x a day with the test tube and eye dropper. Now we have blood testing meters and CGM’s and not just one CGM which was true for a long time but different kinds and types. Or all the new types of insulin. I was one shot of Lente each morning and now we have choices, a lot of choices. Or the different pumps or ways to help us keep track of which insulin we’ve already taken. Apps galore to help us maintain our diabetes. I mean the list goes on and on.
I really do believe things have been moving so much faster than it did back in the 70’s. And while I want it all and I want it now, I realize after doing many clinical trials, these things take time. So while I use the Dexcom and am very happy with my choice, it works and has what I need. But the Libre might be the perfect fit for someone else. And while I use a Tandem pump, I will continue to use it until it dies or the new iLet pump hits the market. I have been watching for years and can’t wait to get one. But it is a waiting game and who knows maybe when it hits the market, there will be something I don’t like and may have to go in a different direction.
So, I am thrilled you keep pushing forward for your child, but take a deep breath, this is a long and currently forever chronic condition. It sounds like you have a great handle on it and I know you will do the parent fight for what you know your child needs. Keep fighting and keep a positive attitude. Your child knows everything you say and think. I know from experience. I heard and understood from the very beginning that diabetes was not going to be good. I heard and knew all the horror stories that they thought they were keeping from me. Us kids hear and know a lot more than parents think.
So see if you can try a Libre and if not wait it out until after the G6 comes out. Maybe the G6 will be the answer you are looking for. Good luck and my thoughts and prayers are with you!


Thank you all for the support and information. Yes, my daughter’s t1 that hit us 2 years ago like a freight train while strolling in the park changed our life forever. I just hope for all of us that the long-promised cure or a decent biological solution will be indeed available in a few years, even if that were just a re-creation of beta cells for a few months at a time.
Back to the topic, it’s true that I am a bit confused by the “filament” vs. needle for the Libre. The Abbott rep described a filament as being 5mm x 0.4mm, but all I’ve seen in photos (like the one kindly posted in this thread) is a rigid needle, which does indeed look of that size. I thought Dexcom is using a filament that is inserted with a needle but that doesn’t seem to be the case here. (And, btw, I do recall Dexcom’s news about a future G6 having either a smaller filament or insertion needle. But the Verily product being 1 year away would be a long wait… ).
So it seems that Libre has a needle that just stays in. Dessito, or any other user, can you please elucidate this issue and, if there were a retracting needle and separate filament, what is the size of the filament? Thanks.

The libre does not leave a “rigid needle” inserted into your skin. It is a flexible filament in the exact dimensions that you mentioned previously. I admit it does look rigid and much like a needle in photos, but i am flicking the filament on mine right now and it is anything but rigid. It’s very flexible.


The little filament really is very comfortable and painless in almost all of my insertions. My left arm tends to feel it very slightly more than my right, but usually only for 30minutes or so.
The filament feels springy but flexible, kind of like a tiny bit of carbon fibre (very much like my carbon fibre bagpipe drone reeds if that’s any help - probably not😛).
The needle is probably as thick as the Medtronic Quickset insertion needles, but I generally feel it less than cannula insertions.
I met a little girl (7yo) with a Libre while I was traveling in South Africa last week, she barely felt hers at all, and was busily flinging herself off a mechanical bull at the time.

It is like a pump infusion set, the 6mm one. Soft as well. And it’s being inserted at a 90 degree angle. Dexcom is longer but thinner i think, but manual insertion of a Dex is a more stressful moment.

Thank you guys. Now it’s all clear. Too bad they didn’t make it smaller. In my opinion, a 3.5mm x 0.2mm would be the max to be able to call the pricking piece a reasonably comfortable wear, for a child at least. The pain factor is the main consideration but – and I know many will not agree with this – we need to also minimize the risk of site damage/infection through long-term usage. We’ll stay with the meter and keep an eye on this and upcoming cgm products. I once read (and didn’t bookmark that link either) about a prickless device being in the works, should such a wonderful thing work.


Sorry if already obvious but if not, be aware that site damage is entirely different discussion when speaking of insulin delivered through pump infusion sets as compared to glucose monitor sensors.

Our approach is to hope for future advances for both technical, medical and biological. These are all great and give a lot of hope for the future.

However our day to day decisions are based on the reality of what we have to work with today. We make what we believe to be the best treatment decisions for our particular set of circumstances entirely based on what is available today.

If you are concerned over what a particular device may feel like, perhaps you could (as a parent) wear one yourself for a period. This would actually give you first-person experience and may help to provide you with additional relevant information that could be beneficial. Our non-diabetic Endo does this to give her a bit more personal experience. It will never be the same as being diabetic but it is something.

this isn’t an issue like it is with insulin infusion sites, Lucian.

I’ve read this thread but remain uncertain about the actual configuration of the Libre glucose monitoring system, particularly how the sensing element is placed under the skin.

I do not use the Libre so I have no first hand experience. I do use the Dexcom G4 system and I had assumed that the Libre worked similarly and now I’m not so sure.

The Dexcom uses a hollow introducer needle that contains the sensor wire. Once the introducer needle with the sensor wire is inserted under the skin, the introducer needle is then withdrawn leaving the smaller sensor wire embedded in skin tissue.

The Dexcom system use of an introducer needle means that the needle is necessarily a larger diameter than the sensor wire it houses. Doesn’t the Libre work in the same way? Doesn’t it use a larger diameter introducer needle and then leave behind a smaller sensor wire or filament?

Or does the Libre simply use a stiff enough sensor element that can be injected under the skin by itself?

dunno either, Terry, but the photo depicts a rather blunt dark shaft, so I doubt it has skin-piercing capability. Guess we just wait for a user to tell us.