Freestyle Libre - Coping with inaccuracies

They have been mentioned many many times

The libre is working very well for my wife - the first few months I almost threw the reader in the woods - something changed in the last 6 months that it has been working decently - it is very accurate in the low ranges and has helped to avoid many problems

I do think however the board of abbott should be in federal prison along with all those at the FDA who approved no fingersticks

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always nice to hear from tony24. I find it amusing the libre is approved for no fingersticks and the reader is a precision neo glucometer…I again wanted to express my preference for xdrip and the miao miao, if I had to stick with the libre reader, waiting 12 hours for the 1st reading every 10 days, no alarms, I probably would have sold my soul to go back on the Dexcom.

My wife finally got the 14 day - last order - a lot less planning because I like her to have it at night

The last 6 sensors have been working so well she is down to one or two sticks a day from the 4 to 5 before.

Medicare cut out strips if you use the libre which I have to fight

I just had my A1C checked and it is 7.2. The Freestyle Libre estimated my A1C at 6.6 based on my readings for the past 90 days. So, the Libre is off by about 20 points in regards to blood sugar readings.

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I find the freestyle to be inaccurate in two ways. The first is that it doesn’t determine my glucose levels in any way that can be trusted. Yes I know it is interstitial glucose, not blood glucose. Abbot claims they have proprietary algorithms that can translate between the two. The second is that the difference between my ten finger sticks a day and the raw data from the sensor is inconsistent and not proportional. The variance is really, well, variable. Again I know the difference between interstitial glucose and blood glucose. In my body, after months of paying attention, I have found a change in blood glucose is reflected in my interstitial glucose after fifteen minutes. That means the changes in glucose between ginger sticks and the freestyle sensor should approximate eachother. Sometimes yes, sometimes no. Overlay the graphs of the two, they should have about the same shape. Not always.

I do however get value from using glimp. It tries to calibrate the raw data from the sensor to my finger sticks and after twenty or so sticks over two days, it is pretty close. I have learned which foods cause sharp spikes and which cause gentle rises. I can see my Dawn Phenomenon clearly. It also gets me to stick my finger more often.

The freestyle Libre sensor and reader however are far from accurate enough, by themselves, to eliminate fine sticks. I have had a wide range of experience with the sensors. Some are rather stable, others are all over the board. I do put them in basically the same spot to reduce the placement variable.

Is not where it should be, reliability or accuracy wise to be sure, but it’s better, in my opinion, than fiber sticks alone.

I just wanted to put my 2 cents in, 10 or 20 glimp calibrations, and even 10 fingersticks with the libre seems excessive. In all glucometer manuals, they state that during insulin shots and food consumption, the readings may be off by as much as 70 mg/dl, and they should be within 20 mg/DL to blood labs during fasting which is the accepted accuracy fda requirement. I personally love cgm s because of the arrows and predictions, and although the glucometer readings may not match, during meals and insulin shots, they really are not supposed to match…I still prefer xdrip to glimp and with the exception of maybe 1 bad sensor, I have never had the libre tell me i I’m hyperglycemic when im not or vice versa…cgm = arrows, arrows, arrows

I did write a comparison between the two under “Choosing a CGM”. I wore the Libre for a year and when I first started the Dexcom I wore both for a few days.

I ended up with the conclusion that while the Dexcom is better because you can calibrate it, there are downsides to it so I didn’t give a huge win to the Dexcom.

I read somewhere where someone said you have to decide to trust and commit to using the Libre. And that was true. I overlapped the sensors the first day to help and did a couple of finger sticks that first day and then I would add on the difference in accuracy which was usually around 20 points and go with it. Sometimes I wouldn’t be finger sticking until the next sensor or half way through just to check or if I felt I needed to verify. There were some sensors that the numbers were all over the place and those I would call for a replacement.

I am one that will happily not finger stick over small amounts of differences and go with the data provided. But you can’t totally eliminate finger sticks. That would be ridiculous, first it’s off and you can have some sensors 40 points off, ( I would get a replacement for those) some 10 points ( I loved those ) I had a few that were 5 points under and then 30 points over, again I would get a replacement for those. And you have to be able to finger stick to know!

And that ends up giving the win to the Dexcom because you can calibrate it and then it becomes fairly accurate from day 1. It was always a joke with Libre they would say we will send you a new sensor but really you should wait for 3 days for it to be more accurate. WHAT??? lol, okay 10 day sensor but minus 3 days so really 7 days…
And I found that 3 day mark didn’t change the readings much.

It was easier to just take them back to Walgreens and tell them they were too far off and they would happily replaced them.

Glimp will not work with USA 14 day sensors -

I have found glimp to be useless, however the glimp folks have solved a problem I had with it and respond to emails

All of the add on devices like miaomiao and blucon won’t work with the U.S. 14 day sensors either although spike/xdrip are working on it. In the meantime I’m just dealing with not having alarms and hoping insurance will approve dexcom.

Walgreens replaces sensors without question if you tell them they are faulty or too far out of range?

@mistermister. yes but only if you got your prescription through them. They never gave me any grief about a sensor that was off by too much and it was easier than dealing with Libre sometimes. I just took back the box and sensor to them.

Freestyle Libre, What a disappointment! I just recently been placed on the FreeStyle Libre system in the past three months by my physician. Well, that was the worse suggestion ever. Using my finger-stick test to compare readings I found the first two FSL sensors where between 30-150 off.
I contacted FreeStyle Libre support, thinking maybe bad sensors, and the only help they provided was to replace my two sensors. Since this I have used three other sensors and they also were between 50-125 points differences from my finger-stick meter. You’re thinking I have a bad finger-stick meter, wrong. I tested the FSL sensor with 4 (Four) finger-stick meters, all at the same time and same finger stick area. The Finger-stick meters were all within 3 points however, the FSL was 50-125 off!
I then waited, using the same testing method over an additional 3 FSL sensors, I obtained the same results.
I reported these anomalies to the FSL support desk and they explained rather harshly I was doing it wrong, I then just hung up on them.
Personally, I will no longer use the FSL for my CGM. I will also have a conversation with my physician and express my concerns on why I think they should NOT be recommending the use of FSL to other patients.
To put a little icing on this cake, after long hours on the internet I found that FSL will not provide or let us, the users, know that these FSL sensors are only accurate between 20% to 35%, sad!
I have type 1 diabetes and trusting test results in life saving for me and FSL is not to be depended on, your life may depend on their non-existent accuracy.


It works for some and not for others - initially it was horrible for my wife but lately has been fine (down to 1 or 2 sticks a day) and has saved many problems with lows.

I have stated before that the board of abbott and whoever approved on the FDA for no fingersticks should be in federal prison

To top if off now medicare refuses to pay for strips because of the no fingerstick claim

Def complain to the doctor -

I share your disappointment. Its like getting a toy home and finding out it is profoundly broken. Waves of disappointment wash over me.



I really liked your post. Strange to relate, I have multiple glucometers. I lined them up, scanned my Freestyle Libre and then stuck myself twice for each of the three glucometers. The variance in the readings was astounding. In the end, I did some research and found that, according to a number of studies, the Contour NextOne was considered the most accurate. That is the one I use exclusively now. I dump BG data to Excel and relax whilst producing cool color charts that only I will see. I do learn a fair bit about things, however, so I don’t consider it a folly.

So the CGM world is falling apart

Eversense is going to take some time for medicare approval
Libre works great for some and not at all for others
Dex is falling apart at the seams
Medtronic does not even deserve a comment

Just sayin

Dexcom CGM’s work well–let’s not freak because of the offshoring. :slight_smile: I don’t LIKE that they are doing that, but let’s not get ahead of our skis, shall we?

How are we getting ahead of our skis when they nothing but complaints?
Offshore has nothing to do with it
Yeah, their stuff works - so does the Concord

“Nothing but complaints” is NOT accurate. If you go elsewhere on the 'net you will see as many people (actually MORE) loving the accuracy of the G6 and not everyone has issues with ordering supplies. The vocal minority can seem as if they are the majority because they complain the loudest.

Time will tell