Libre users - thoughts on readings

[everydayupsanddowns]

9 minutes later (cos I needed the loo) BG meter said 11.4 so I've had a correction and then just for the hell of it scanned again - 10.4 and upward arrow. Does not exactly compute in terms of arrows anyway. That's a bit odd.

Level arrows on Libre aren’t all that level tbh. They simply mean a change of 0.06mmol/L or less per minute. Which sounds like nothing, but if it’s at the upper end of that, it would still be +/- 1.8mmol/L in 30 minutes which is quite a change at lower levels.

Plus there’s a bit of Libre ‘fortune telling’ going on with the scans, as the algorithm tries to predict results based on direction of travel in an attempt to close the 10-15min lag down closer to 5 mins. which is why you sometimes get scan ‘outliers’ that the graph (based on more datapoints) never quite reaches - particularly where levels are changing more rapidly.

 

[Squirrel768]

I agree with @grovesy - App and reader should be the same as far as I am aware.

I know you have said you've started using recently, but is there a chance your reader is still using the older algorithm? That’s the only reason I can think why they may be different unless you are timing scans just either side of the sensor datapoints?

Reader was delivered approx. 8 weeks ago, phone is a Galaxy A50, so quite recent as well (not that should affect the actual app being used, which I downloaded again approx. 8 weeks ago.

Been using Libre now for 4 weeks today, following an online intro session (because the original one at the hospital was cancelled in March, and currently not doing the physical ones). So, 6 months later than originally planned to start it - but got there in the end 🙂

If the two scans were either side of the sensor data points, I would expect possibly a small variation (if the trend was in top gear either direction), but not if both are showing flat. Also, with the number of double-scans, the liklihood of them all being split over the few seconds between them is highly unlikely.

The current sensor does seem to be a bit more stable in that respect, and sometimes the reader is even below the app, or the same, but mostly still reading higher. Examples the last few days, (app then reader, trend both flat unless mentioned) 5.8 and 6.2. 8.3 and 8.7. 7.7 and 7.8. 8.9, 8.8. 8.4, 8.9. 7.1, 7.2. 8.7, 9.2. 4.8, 5.4.

Given that it is the sensor which holds the data, and both devices are reading the same data, something somewhere appears to be out of synch.

I'm currently building a spreadsheet with the comparative levels, to highlight especially when they are significantly different. Also, seeing the differences, my attention to detail from back in my work days gets my curiosity going, as to where the differences are coming from! (Used to dig through and pick out loads of little details, to get the differences in area measurements down to zero, or where the sums were going astray on the budget side ... sense of triumph when I found those obscure little details LOL.)

And now, bother! I thought I had got past the post-lunch spike in range, but no ... 11.1/11.4 LOL. Do I adjust the bolus, or watch and wait? Decisions, decisions ... OK, another 2 units 🙂

 

[everydayupsanddowns]

You could try visiting this page

FreeStyle Libre Reader Update for Even Better Accuracy

Update your FreeStyle Libre reader to get even better first day accuracy and overall accuracy for the entire wear period.

www.freestyle.abbott

To see if your reader software needs to be updated - though it sounds too new for that!

Might be worth giving Abbott a call for an explanation?

 

[Squirrel768]

I agree with @grovesy - App and reader should be the same as far as I am aware.

I know you have said you've started using recently, but is there a chance your reader is still using the older algorithm? That’s the only reason I can think why they may be different unless you are timing scans just either side of the sensor datapoints?

Hi Mike,

9 weeks in now!

Since doing the android app update to 2.5, I am finding that the two readings are, in general, a lot closer than before, but apart from a very few, there is still a disparity between the two readings taken at the same time. I would have expected both to use the same algorithm to process the same raw data, and therefore come up with the same results. I also find that as well as the difference in readings, they can also give a difference in trend direction (usually with the app showing a slope and the reader showing flat).

I agree that there is a chance of the readings being either side of a data point, but given that the few seconds between taking the two readings would have a small chance of being either side, and almost always being within the same 60-second segment.

Apart from that (which I think comes down to my technical background and having frequently to hunt for the cause of something not working - sometimes something pretty obscure at the root of it ) I'm loving the extra data and trying to stay in Norfolk instead of the Himalayas

 

[Bruce Stephens]

Since doing the android app update to 2.5, I am finding that the two readings are, in general, a lot closer than before, but apart from a very few, there is still a disparity between the two readings taken at the same time.

I've started noticing the same.

 

[nonethewiser]

One thing narks me. Find libre accurate & reliable most times & don't have to many issues with it, but very odd time on waking reading will be higher than bg test.

Example this morning, scanned 10.1 bg result 6.2 , waited 20 mins for insulin to kick in started having breakfast, decided then to scan & result was 6.1 , but looking at graph no sign of the 10 reading & smooth line in the green zone all night.

How do you make sense of that? Didn't lay on sensor or owt like that, just as well checked bg or hypo would be inevitable after brekkie.

 

[grovesy]

My current on is up and down and down but it is nearly finished .

 

[helli]

One thing narks me. Find libre accurate & reliable most times & don't have to many issues with it, but very odd time on waking reading will be higher than bg test.

Example this morning, scanned 10.1 bg result 6.2 , waited 20 mins for insulin to kick in started having breakfast, decided then to scan & result was 6.1 , but looking at graph no sign of the 10 reading & smooth line in the green zone all night.

How do you make sense of that? Didn't lay on sensor or owt like that, just as well checked bg or hypo would be inevitable after brekkie.

I believe, because of the 15 minute delay with interstitial fluid, the Libre software makes an attempt to predict your blood sugars. Once it receives the actual value, it updates the prediction. As a result, you may see a high (or low) which then disappears.

 

[nonethewiser]

I believe, because of the 15 minute delay with interstitial fluid, the Libre software makes an attempt to predict your blood sugars. Once it receives the actual value, it updates the prediction. As a result, you may see a high (or low) which then disappears.

Thanks, sorta makes sense, but why predict high reading of 10 when all night been sitting around 6, why not predict somewhere around that figure.

 

[helli]

Thanks, sorta makes sense, but why predict high reading of 10 when all night been sitting around 6, why not predict somewhere around that figure.

I assume because your blood sugars were rising at the point of the calculation.
But I am guessing.

 

[trophywench]

How on earth does one input your actual BG into the Libre?

 

[helli]

How on earth does one input your actual BG into the Libre?

If just using LibreLink (or the Libre reader), you can enter it as a comment. Libre does nothing with it but you have a record of the difference.

if you are using an unofficial phone app such as Glimp, Spike or xDrip, you can add the finger prick reading to be used for calibration.

I have used the latter approach since starting with Libre because a seem to differ from “factory man” (Libre is “factory calibrated”) so need to calibrate it to my body.

 

[trophywench]

Oh I see - you have to tell it after, by going in and checking your results, then adding a note. Spose I could do em all once a day or something by having the 'memory' of both Libre Reader and meter open at the same time.

 

[Martin the Spartan]

Anyone noticed the difference regarding being horizontal and vertical? eg: this morning in bed 4.6 and dropping, well I thought I better get up and have some food (it was 09:00 & I was planning a bike ride) by the time I had gotten downstairs and put the kettle on I was 6.7!! (4 mins later) my wife said "whats the fuss about then?" I blushed and made the tea.

 

[Robin]

Anyone noticed the difference regarding being horizontal and vertical? eg: this morning in bed 4.6 and dropping, well I thought I better get up and have some food (it was 09:00 & I was planning a bike ride) by the time I had gotten downstairs and put the kettle on I was 6.7!! (4 mins later) my wife said "whats the fuss about then?" I blushed and made the tea.

My Blood Glucose always starts shooting up as soon as my foot hits the floor in a morning, it’s my liver pumping out some glucose to help kickstart the day, nothing to do with Libre reading low if I’m lying down (unless I’m lying ON it, in which case it will give me a compression low).

 

[rebrascora]

@Martin the Spartan
As @Robin says, it is Foot on the Floor (FOTF) syndrome which is similar to Dawn Phenomenon but a little more sociable. I usually need to inject 1.5 units of bolus insulin for it as soon as I get up as mine will often take me from a nice 5 reading up into the 9s if I don't quash it with insulin.