Libre & Flying

[Deleted member 35955]

Hi Claire Diane, you might find it helpful to read through our information on Travelling with Diabetes: https://www.diabetes.org.uk/guide-to-diabetes/life-with-diabetes/travel. The section on 'Travelling Abroad with an insulin pump or CGM' in the middle of the page may be useful! Enjoy your travels 🙂

 

[Purls of Wisdom]

@Purls of Wisdom , if you are using Libre, be aware (very aware) of its limitations. These have been mentioned many many times on the forum although DSNs rarely mention them and Abbott never do.
The key ones are
- many people find their body needs time to get used to a foreign object embedded in their arm. For this reason, the first couple of days, the Libre readings can be off. Some people apply their sensors a day or two before activating them.
- sensors do not measure blood sugars, they measure interstitial fluid and then apply an alogirithm to convert this to blood glucose. Interstitial Fluid Readings tend to be 15 minutes behind blood sugars. The algorithm predicts the last 15 minutes by extrapolating the current trend. This works pretty well if the current trend continues but, if the trend changes direction in those 15 minutes, the algorithm does not know. Therefore, if you treat a hypo or do rigorous exercise or something else which changes the direction of trend, the Libre reading will be inaccurate. Hypo treatments will always appear to take longer to recoved so always check hypo recovery with a finger prick
- sensors are calibrated to be most accurate when in a "normal" range. This is around 4 to 9 mmol/l. Outside oft his range, Libre can be very inaccurate. Unless you are clearly experiencing a hypo, all highs and lows should be checked with a finger prick before treating.
- libre is "factory calibrated" and you have no way to officially overwrite this. Some people find they are different to "factory man" and the sensors are always off. There are third part unofficial apps which use a different algorithm which allows calibration so are more accurate
- LIbre sensor accuracy can drift so it is recommended to check with finger pricks at least once a day, Always check when levels are in the normal range and when not changing fast.
- Some sensors are too far out or just fail. Abbott are pretty good at replacing these. However, some people are more susceptible to failures than others.

This may all sound daunting but Libre are a great tool ... if you know how their limitation and how to use the data they provide.

It has been 2 days since Libre 2 is operating. I am still doing finger pricking. I wonder when can I safely stop finger prick testing? Keeping in mind that I must do it once daily. Any particular time one would suggest?

Thanks. X

 

[Proud to be erratic]

Alas, as with so many aspects about DM, there is no definitive answer to your question. It depends:

If my early finger prick readings show some similarity to my Libre, when BG is steady and level then I relax and may not finger prick at all. For that scenario I need to be in range (4-10) and getting a full 24 hrs like that is rare, but does happen. I rarely have a Libre that is within 1 whole unit of my BG, usually nearer 2 above my BG and I mentally calibrate my Libre readings to actual, respond is if in range. I will bolus for food from just Libre readings and even make corrections, but with an awareness that Libre isn't accurate.

Several Libres have started high and progressively got closer to actual (in steady state) then ended up below actual. This is frustrating, but manageable. Whenever I finger prick I always take a Libre scan and add that info to the notes - e.g. "L2=8.4, Act=6.5"; I do this so I don't have to completely trust my memory of what the differential is (was).

Don't get bogged down in decimal places and presumed accuracy. Both Libre and your test meter have defined tolerances for their accuracy; there is at least one person on this forum who rounds off all readings to the nearest whole number. Also don't be surprised if readings change quickly without an associated trend arrow. This morning I woke, scanned recorded 5.8 level (knew that is closer to 4.8 or 5 actual BG); went to the bathroom and 30 seconds later the scan showed 7.3 still level. Such changes are more evident first thing when the "Foot on the Floor" BG elevation can occur; but my underlying point is that there can be modest variations just because .... there can be!

In practice most days I either get too close to showing hypo or near hypo to trust my Libre scan and I spend chunks of time showing hyper. So I finger prick and reassure myself. On a busy BG day I can FP 5 or more times; on rare days no FPs.

The limitations that @helli listed are, in my opinion, absolutely vital to get an understanding of what you are trusting .... and I'm amazed that the NHS doesn't spell these out!

 

[rebrascora]

Once I have confidence that my Libre is reading reasonably accurately (within 2mmols.... ideally within 1mmol) I don't finger prick unless the Libre doesn't agree with how I feel and I am very confident to bolus and correct from it, so I can go several days without needing to finger prick at all but other days I might need one or two or on a bad day 3 finger prick checks.
In the first couple of days of a new sensor I will choose times whe my levels are nice and stable for an hour according to Libre and then do finger prick checks to see how close it is. Once I have a feel for if it is reading a little higher or usually consistently a bit lower than finger pricks I just bear that in mind when I am calculating corrections and boluses or working out if I need a few carbs to nudge my BG levels a bit higher. Libre is pretty accurate for me most of the time and I understand it's limitations well so I have lots of confidence in using the data it gives me without the need for finger pricks to check or bolus from.
You have to find what you are comfortable and confident with.