Hi,
second post so if its irrelevant then please delete. I have just started a trial on the freestyle libre, I am just enquiring to see what the reliability is like and to see if I should still finger prick? I know its interstitial blood that it analyses. but has anyone found a big varience from their previous meter?
thanks for all advice
Hi.
I have been using the Libre FreeStyle on and off for about 9 months since I went on the I HART diabetic research trial last year.
The Libre does not replace your blood glucose meter; it is supplementary to it. I have found that there can be significant deviations between the readings.
These are my observations:
1. Interstitial readings are not the same as blood glucose readings so are not comparable
2. The latter are more up to date by about 15-20 minutes than the Libre
3. The Libre must be using some kind of averaging algorithm to calculate a number that approximates to your blood glucose reading and to give an indication of the direction in which your reading is heading. This is not foolproof.
4. At times, no direction indication is given at all even though subsequent readings show falls or rises
5. I have had up to 4 consecutive readings during an hour on the Libre that were lower each time, but which we indicated as "Stable" i.e. not rising and not falling. This resulted in a hypo.
6. Because of the delay it can be hard to anticipate or avoid hypos if you have few warnings
7. When your blood glucose meter reading is higher than normal, the Libre system seems to indicate significantly higher results than my meter. I have experienced up to 45% difference!
8. I have checked my BG meter with control solutions and it is bang in the middle of the expected tolerances
9. In terms of reliability, I accidentally knocked a sensor during the I HART trial when I was working in a confined space. This rendered it "dead".
10. Since then, I had one sensor that stopped working just over 24 hours after it was applied. Abbott agreed to supply me with a replacement.
11. I have seldom had readings that agree with my BG meter. Those that are close are always at the low end of the spectrum.
12. You might think I am being critical of the Libre system but it has several benefits:
a. You can take as many readings as you like (I have even done them while driving)
b. Overnight it stores up to 8 hours data which it downloads to your reader so all the gaps are filled in
c. You do not need a reader if you have an Android smart phone (as I do) and the LibreLink App
d. Another person can also monitor your levels on their own phone (Useful for partners and parents)
e. The dedicated reader costs £160 so if you already have a smart phone you can avoid buying the reader
f. There are lots of useful statistics that are provided with the LibreLink App
g. These can help you identify regular patterns that can be addressed by dose changes either in your basal or bolus
h. The direction indicator is a real boon in warning about undetected hypos approaching
i. The sensor requires no calibration
j. The sensor is easy to apply
k. It is really useful during energetic sports activities for ease of checking
l. It would be good as a short term monitor for hospital monitoring and dose adjustment purposes
m. The Libre is waterproof for up to 20 minutes so showering is not a problem. I have not tested it for a long swimming session. I might do this when a sensor is nearing expiration.
13. There are some disadvantages:
a. Cost (It is not currently funded on the NHS, but this may change)
b. It cannot actively warn you that a hypo is imminent (You must scan to get a result) so night time hypos may be missed
c. Direction indication may be missing or incorrect at times
d. It is not a substitute for your BG meter
e. I have noticed some initial discomfort (which usually disappears and is replaced by itching) after applying the sensor
f. As yet, I have not found a way to download the data from my smart phone to Diasend
g. Because of the delay factor, it is very easy to over-react to an anticipated hypo resulting in larger than necessary swings in BG levels
h. When dealing with hypos, your BG meter should be used because the delay factor is too great to ascertain if your corrective action is working or not
i. I would not want to rely on it for dose calculation
Sorry if this has been overly detailed but I feel it is best to be honest. Overall I would give Libre 4 starts out of 5. Perhaps the calibration and direction algorithms will improve with time and controlled trials. It will never be able to actively warn you that you are going low. Only the Dexcom system can do that, but it is not available to buy in the UK yet.