Hi, i started using the libre 2 sensor yesterday and some of the readings are totally out with my blood pricking, which i am doing to double check, as in this morning sensor said 3.9 but when i.did a finger prick it was 7.1 and a little while ago it said 3.8 and finger prick said 5.5, so is there any point in using the cgm if the readings are so out with each other x
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Accuracy of libre 2
- Thread starter kellie01
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rebrascora
Well-Known Member
- Relationship to Diabetes
- Type 1
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- She/Her
When did you do the first test? If it was as soon as you woke up, had you been lying on the sensor as that will cause false lows which we call "compression lows"
With the second set of readings, did you have food and insulin in your system. There are times when Libre is following a trend and hasn't caught on that things have changed, so say you prebolus your lunchtime insulin and gave it half an hour before you ate lunch by which time your levels were coming down, but then the carbs from your lunch start to digest and hit the blood stream and then your levels are coming back up but the Libre algorithm is still extrapolating the previous downward trend, so it shows you as going lower than you actually are when your levels are in fact starting to rise. These changes of direction of BG from falling to rising or rising and then a correction dose of insulin bringing you down are when Libre is least reliable, because of the algorithm which tries to make up the lag between BG and interstitial fluid. I generally just double check my Libre for comparison to a finger prick when my levels have been stable and mid range for at least half an hour.
Understanding the way in which Libre works and its quirks and limitations is really important in getting the best from it and becoming confident with the results it gives you. We have a post which was very thoughtfully composed by @helli about these quirks and limitations which it would help you to read....
forum.diabetes.org.uk
With the second set of readings, did you have food and insulin in your system. There are times when Libre is following a trend and hasn't caught on that things have changed, so say you prebolus your lunchtime insulin and gave it half an hour before you ate lunch by which time your levels were coming down, but then the carbs from your lunch start to digest and hit the blood stream and then your levels are coming back up but the Libre algorithm is still extrapolating the previous downward trend, so it shows you as going lower than you actually are when your levels are in fact starting to rise. These changes of direction of BG from falling to rising or rising and then a correction dose of insulin bringing you down are when Libre is least reliable, because of the algorithm which tries to make up the lag between BG and interstitial fluid. I generally just double check my Libre for comparison to a finger prick when my levels have been stable and mid range for at least half an hour.
Understanding the way in which Libre works and its quirks and limitations is really important in getting the best from it and becoming confident with the results it gives you. We have a post which was very thoughtfully composed by @helli about these quirks and limitations which it would help you to read....
CGM limitations and precautions
Moderator Note: This helpful reply was copied from another thread as it details some of the commonly experienced limitations of continuous glucose sensors. My blood sugar has been in perfect range for days now, but although I haven't changed anything, I'm starting to get very short periods of...
forum.diabetes.org.uk
John Gray
Well-Known Member
- Relationship to Diabetes
- Type 2
@kellie01 Try the Libre 2 Plus sensors, which are replacing the Libre 2 sensors. Abbott says that they are (somewhat) more accurate.
What @rebrascora (and @helli!) says above still applies, though!
What @rebrascora (and @helli!) says above still applies, though!
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