Freestyle Libre - how accurate is your sensor?

[Northerner]

I thought it might be a good idea to start a thread about how accurately their sensor is behaving compared to blood tests. I've just started a new sensor and readings are:

5.5 mmol/l - scan
6.5 mmol/l - blood test on reader
6.8 mmol/l - blood test on Contour Next USB

Happy enough with that - always a tense moment when you take that first reading, hoping it's not way out! 😱 🙂 Most of my sensors have read slightly lower than blood tests, and this one looks like it will fit that pattern. I don't mind that because it means I tend to run my levels a bit higher in reality to avoid getting hypo readings on the Libre 🙂

 

[Robin]

Interesting exercise! I checked my new sensor against my meter when I started it up, and it was 5.7 against 5.8, so very close, and it's been accurate in the mid range ever since. ( I usually find the Libre reads lower at the bottom end, and higher at anything in double figures)
So I just did a check, and this was the result. I'm particularly surprised about the upward arrow on the Libre, after 10 minutes it was showing 7.6, now after 15 mins, it's 7.4, both with a horizontal arrow. It's got 3 days left to run, wonder if it's going off a bit. ( I double checked on the meter, and it was 5.8 ten minutes later, so if the real result is somewhere in the middle, I guess they're both just about within permitted tolerances)

 

[SB2015]

The difference here is because I have just eaten and BG is already rising.
I think of the Libre as what my glucose was 15 minutes ago, and the BG is what it is now.
The meal we had is going to spike a bit but I know I have insulin dealing with that so not worried.

In general I find if there is a big unexplainable difference it is often because I am dehydrated.

PS very happy with flappy fish profile during today!!

 

[PhoebeC]

Love this post.
Only got one meter so can’t join the fun x

 

[everydayupsanddowns]

I compared some readings for my first 2 sensors way back in 2014. Most of the sensors I've used have performed really well, as the forst one did. Frequently there being less than 0.5mmol/L difference between fingerstick and Libre (around half the time). On average I seem to get 0.7mmol/L difference (ranging from 0.1 to 1.3mmol/L out).

http://www.everydayupsanddowns.co.uk/2014/10/abbott-freestyle-libre-results-vs-bg.html

Of course you can't really compare the two, as one is measuring tissue glucose, the other capillary blood. Plus sensor lag (and Abbott's algorithm to attempt to reduce that).

And then again there's no guarantee which of the results would be closest to a lab value!

 

[Radders]

Usually within 2 of each other. Always read low at the bottom end, telling me I’m hypo when I’m below the mid 4s.

 

[mikeyB]

If I’m below the mid 4s, I look at the arrow to see whether that is stable or downwards pointing. That’s the joy of the Libre. A downward pointing arrow would induce me into eating a couple of JBs.