Freestyle

[CoventryTrev]

Today my diabetes nurse put me on the Freestyle Libre 2 monitoring system.
I'm glad because it saves pricking my finger four times a day but how accurate are they?

 

[Lily123]

They can be very far out for some people and near exactly accurate for others.It isn’t a good idea to replace finger pricks with Libre

 

[helli]

Today my diabetes nurse put me on the Freestyle Libre 2 monitoring system.
I'm glad because it saves pricking my finger four times a day but how accurate are they?

It depends. There are some limitations and LIbre does not take away the need to do all finger pricking.
- Some of us find it takes a day or two for the sensor to "bed in" so the first couple of days after application may appear a bit random. If you find this is what you experience, in the future, apply your next sensor when your current one has a day or two of life left in it. That way, it will have bedded in by the time you activate it.
- Libre is calibrated to be most accurate between about 4 and 9 mmol/l. Outside this range, it could be less accurate. Therefore, it is recommended to test with finger prick before correcting a Libre high or low.
- If you apply pressure to a sensor, it can report a false low. These are called compression lows and typically happen at night when you lie on your arm. This is another reason to test if your sensor reports a low.
- Libre reads interstitial fluid which is about 10 to 15 minutes behind finger prick blood tests. Libre applies an algorithm to convert from Interstitial fluid reading to BG,. This algorithm predicts the "delay" by extrapolating the current trend. This is great most of the time but, because of this approach, it can be slow in spotting when the trend has changed direction. This is most obvious when you have treated a hypo with fast acting carbs. Libre seems to take forever to notice the recovery. Another reason you will need to finger prick.
- Some sensors can drift during their lifespan. Therefore, it is recommended to check against a finger prick once a day when your levels are stable and between 4 and 9mmol/l.
- Libre are factory calibrated. Some of us seem to have a body just like "factory man" and some of us don't and find the readings can be consistently off. If you are technically minded, there are some unofficial phone apps (I used to use xDrip+ on my Android). One of the advantages of these apps is that they allow you to calibrate your sensors. The otehr advantage is you don't have to scan the sensor after it has started.
- Recently, I have found my sensors are sensitive to heat. Not ambient heat but constantly applied heat. My partner describes my showers as "scorching". I find it refreshing. My sensor reports a spike which comes back down with no insulin when I have dried myself off which makes me believe it is the sensor going high, not my "real" blood sugars.
- Some sensors are just faulty. If you have a sensor which is consistently out compared to finger pricks by 2 or 3mmol/l, it is recommended to report this to Abbott (with evidence from your finger prick meter). They are pretty good at replacing them.

Libre (and other CGMs) are fantastic. They are much much more than finger prick replacements because they give you so much more data - they tell you what is happening in the 4+ hours between finger pricks. But they are only useful if you understand their limitations and are able to convert the data it provides into information (or "actionable insights").

 

[nonethewiser]

Today my diabetes nurse put me on the Freestyle Libre 2 monitoring system.
I'm glad because it saves pricking my finger four times a day but how accurate are they?

Find it very accurate, especially at low & high bg levels unlike libre 1.

It's great piece of kit, makes life so much easier.

 

[Lucyr]

I find it completely accurate for me

 

[EmmaL76]

It’s not accurate for me, but it is constantly different by the same amount if you get me. I’ve gotten used to how it works for me and I’m fine with that

 

[gll]

I have had some completely on par with fingerpicks and some a couple out but same as Emma, they are consistently out and I can work out what it really is (and occasionally verify with fingerpricks)
I am running high at the moment and that can also effect the accuracy if not within normal limits. 🙂

 

[everydayupsanddowns]

I have had great success with various different types of sensors.

They are all a bit ‘laggy’ when levels are moving quickly, and it’s important to remember that sensor glucose isnt the same as capillary blood plasma glucose - but generally I get a very usable flow of data which hugely helps my diabetes management.

Plus of course it’s 3x the information. The level… the direction of travel… and the rate of change.

Some sensors read better than others for me. Sometimes they’ll start a bit wobbly and then come into line, others will consistently struggle all the way through, and others will read bang-on from the start.

Hope Libre2 works well for you 🙂

 

[Proud to be erratic]

I'm glad because it saves pricking my finger four times a day but how accurate are they?

For me neither accurate nor reliable.

My current sensor 4 days ago started 2+ pts above actual when mid range and 1 pt above when low. Today its 1 pt above actual mid range but 2 pts below in low range! This scenario makes it really difficult to continue with this sensor - its happened before; I'm getting low alarms in the night when I'm not low (but must finger prick to check) then the reverse as my actual BG picks up to the 7s. My reliability is such that over 16 months I've had over 50% failures; Abbott have replaced all of those. None have fallen off (they imitate limpets on me) they have either just abruptly stopped early or become unreasonably inaccurate.

I am a huge supporter of the concept of CGM. Despite my gloomy perspective I am in no doubt that being able to get a fast snapshot that gives a figure, the trend and indicative rate of change has greatly improved my ability to manage my DM. My HbA1c results confirm that but for me more significantly my erratic BG behaviour is less so. I persevere with sensors that are inaccurate, mentally tracking the differential and ignoring some of the unsatisfactory LibreView statistics, eg far more low glucose events than have actually occurred. Eventually I have to give in. Its a nuisance having to replace a sensor very early (manageable of course) I need a full day after fitting for it to bed in and become steady and its yet another aspect of unpredictable daily DM management.

I do not think my experience is because I'm T3c with no panc'y; I just think the Libre isn't great on my body but have no experience with any other sensor.

I do not wish to put you off Libre, just manage your expectations and encourage you to work with it as best you can if you find it not as accurate as you anticipate.

 

[CivicFreak]

Today my diabetes nurse put me on the Freestyle Libre 2 monitoring system.
I'm glad because it saves pricking my finger four times a day but how accurate are they?

I have found that they can generally be relied on. I have been using Libre 2 since March and only had an issue with a couple of sensors. My very first sensor fell off after only 2 hours but it was replaced quickly by Abbott, who, for the record, have a really good customer service and will replace faulty sensors free of charge. I have only had an issue with one other sensor consistently being around 3 mmol/L below my finger prick, so again I told Abbott and they replaced it.

For the most part they do seem plenty accurate enough, but it's always worth doing a finger prick every so often to ensure that the readings are consistent, and as @everydayupsanddowns says, there will always be a degree of lag, because the Libre measures glucose levels in your interstitial fluid, and not your blood, so it tends to be a few minutes behind finger prick testing due to the fact that the glucose enters your blood first and will therefore always be ahead of other methods. Having said that, I have generally found the Libre to be usually around 0.5 mmol/L different, which is perfectly acceptable.

After you've been using it for a while, you will also tend to know if it's measuring accurately or not, you will just get a "feeling" for it. For example, I recognise hypos well, and if my sensor is showing I'm within hypo range but I feel fine, then I know it's measuring too low, and will back it up with a finger prick before taking any corrections.