Libre 2

[Oliviag23]

Hi everyone,

I recently started a trial run of the Libre 2 sensor. I’ve been diabetic for 20 years and I’m on insulin pump, but the sensor is new.

Is the sensor worthwhile? It said I was 8.9 and really I was 17.0 when I did a finger prick.

Is this just because it’s new and taking time to adapt? I don’t want to use the sensor if it’s going to be that far wrong.

 

[Bruce Stephens]

Is the sensor worthwhile? It said I was 8.9 and really I was 17.0 when I did a finger prick.

That's a bit far out so I'd report that to Abbott. (There's a form on their website if you prefer that to phoning: https://www.freestyle.abbott/uk-en/support/online-sensor-support.html )

They'll most likely ask for three pairs of readings showing the sensor is significantly different to test strips, so collecting those makes sense.

It's possible Libre 2 doesn't work for you for some reason. Some people find another one works better (like Dexcom One, also available from GPs). (Though some find Libre 2 works better than Dexcom.)

 

[helli]

Libre (and other CGMs) is worthwhile but you must understand the limitation. Unfortunately, Abbott do not mention them and most DSNs seem to be unaware.
Off the top of my head, the key limitations are
- some of us find our body can take up to 48 hours to get used to having an alien object inserted into our arm. During this time, the readings can be erratic. To overcome this, it is common to apply the sensor a day or two before activating.
- sensors are designed to be most accurate at "normal" levels. This is why it is advised to double check highs and lows (unless you obviously need to urgently treat a hypo) before correcting.
- sensors read interstitial fluid rather than blood and use an algorithm to convert one to the other. Interstital fluid will react about 15 minutes after bloods. The algorithm Libre use takes this into consideration by extrapolating the current trend. This is great if the current trend continued in the same direct for the last 15 minutes. But if, for example, you treated and are recovering form a hypo, the trend that Libre knows about is downhill whereas it has now turned the corner. As a result, Libre will take longer to recover from a treated high or low and may overshoot.
- if you apply sensor to a sensor it will report a false low. This is known as a compression low and is most likely to occur at night if you lay on your arm whilst asleep.
- some people find the accuracy can drift over the life time of a sensor. Therefore, it is a good idea to to a mental calibration check against finger pricks once a day when levels are "normal" (not high or low) and stable.
- unlike other CGMs, Libre is factory calibrated and cannot be calibrated at home. Some people find their body does not react in the same way as "factory man" and is constantly out. When I used Libre (I now use a CGM which communicates with my pump), I decided to adopt an unofficial app (xDrip) which enabled calibration.
- some sensors are faulty and Abbott will replace them if you report it. However, I would always double check against the points above before reporting a fault to Abbott. For example, I would not report an inaccurate sensor if it had not had a couple of days to bed in.

 

[Tdm]

Hi everyone,

I recently started a trial run of the Libre 2 sensor. I’ve been diabetic for 20 years and I’m on insulin pump, but the sensor is new.

Is the sensor worthwhile? It said I was 8.9 and really I was 17.0 when I did a finger prick.

Is this just because it’s new and taking time to adapt? I don’t want to use the sensor if it’s going to be that far wrong.

I find a sensor really worthwhile. Data is power. As prev said the first days readings are always iffy, and readings outside the normal range aren't going to be as accurate....but then, with a sensor you should be spending more time in the normal ranges.
Interestingly, if you redo your finger prick test you'll probably find that has a degree of variabilty too...

 

[rebrascora]

Libre is a total gamechanger for me, but as @helli said you do need to understand how it works and it's limitations.

When did you take those readings relative to eating a meal and did you expect your levels to be as high at 17? Did you double check that reading? I imagine you are well aware that finger prick readings can quite easily get contaminated, so double checking an unexpectedly high reading is the first thing to do. It could also be a rogue test strip. When we have been relying on a bit of kit for many years, we are much more likely to be suspicious of the new technology and not consider that perhaps the BG meter could be the one that was giving the incorrect reading.

Could the sensor be not fully adhered to your arm. If it is coming adrift or has come adrift and then been pressed back on, it will usually read low and eventually fail.

If your levels were changing rapidly due to food you had recently eaten, particularly something high glucose or fast releasing, that could account for a large disparity.

If you had been leaning on the sensor, that applies pressure to the tissue under the sensor and causes it to read low and can happen quite frequently through the night if you lie an that arm but might also happen if you were leaning on it in an armchair or something or leading against a wall, on that arm.

I would give it a few days to settle down and give it a fair test and if it continues to be significantly adrift then collate 3 clear occasions when the arrow on the Libre was horizontal but the comparative reading on the BG meter was more than 2mmols different and ring the Abbott helpline to report it.... or I believe there is an online form you can fill in.