Abbott Freestyle accuracy

I have had three of these so far,

The first one gave me readings that pretty much accorded with the Codefree fingerstick tests I had been doing.

The second gave me readings far lower than I expected 4's andf 5's instead of 6's and 7's , though they did agree to the Abbott stick test. I did also check those against a couple of codefree and they showed maybe 0.5 -1.0 under-reporting ie my daily averages were probably closer to 6.1-6.5 compared to the reported 5.4 - 6.1


The third one gave me much higher readings than either of the first 2 and started reporting 10's and 11's that I have not seen in a while using the codefree, Abbott's its own internal blood stick tests were coming out much lower - 2-2.5 mols and the daily averages suddenly became 7+ compared to 5.4 a day earlier. Abbott are sending me a replacement for this one

It is now clear to me by day 3 of each of the three units that the numbers were going to be very different for each monitor. It is very disappointing as clearly it doesn't really help me control anything much if its figures are just random.

Abbott itself said it was ok if the numbers were as much as 30% different between fingerstick and sensor tests - which seems ridiculously high to me. On that basis 7.8 could show as anything from 5.5 to 10.1 , though the guy did also say that if they were obivously more than 2 mmol out it would be replace - ie 5.8-9.8 a slightly narrower range - however as one of those is fine and the other panic I am not too sure what the point of these monitors are now I have tried them.

I am aware that other people have been using them for a while now, It would be useful to know if those who are a lot more familiar with them have also seen this phenomenon - i.e. have your monitors been internally consistent from sensor to sensor or do you know within a couple of days if that particular monitor is reading heavy or light and then make mental adjustments?

Bluetit1802 said:

I think most of us find the same, but to be quite frank I don't take a lot of notice of the actual levels as compared to finger pricks. I look at the variability graphs and the blue band. I have found on my sensors (other than one, which was replaced) that the differences between before and after a meal are consistent with my meter, even if the actual levels are different, and that is mostly what interests me - the rises and falls being kept to as tighter band as possible. Other things also interest me, such as the very small bumps overnight, and the rises I get with exercise. Ignore the levels, look at the bumps.

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My problem has been that with one of the sensor it is almost entirely bump free - ie for 14 days the picture was a solid - 4-5.5 for 18 hours a day and then say 6 hours with a gentle rise in the mornings upto a maximum 8 before coasting back down again - so bascially all in the blue band ( abut 30 g carbs per day_

then when I changed it everything got a lot spikier and the highs turned to 11.5 instead of 8.0 with the spike happening on 0-5 carbs.
so either one of the sensors was dulling everything, or the other is exagerating as I have done very little different on the respective days - including being in about the same level of ketosis. The readings still follow the same patter - i.e morning rise and little in the afternoon but with entirely different shapes .

Brunneria said:

I have been using the Libre for about a year now, part time.

I read other people's stories and issues with interest, but in about 12 sensors, I have
- never had to return one
- never had to ring Abbott and complain about inconsistencies
- had a few dodgy readings, but in every case the sensor just went back to working OK afterwards
- found the sensors are most accurate on days 2-13 of the 14 day life
- lost 2 sensors, one fell off after a hot tub soak, the other was scraped off by a door frame - both my own fault, and I lost a total of about 2 days useage, because they were both at the end of their lives.
- none of the sensors have matched my SD Codefree, and usually score lower, consistently lower, with fewer inaccuracies and rogue readings than the Codefree. Each sensor has roughly matched the Freestyle comparison strips I use, but I just test a couple of times per sensor.

Maybe my body just gets on brilliantly well with the technology? If so I am extremely grateful.

Having said that, I have a carefully understated set of expectations.
I'm not bothered about precision, but I AM bothered about trends and spike timings, and watching for reactive hypoglycaemia, as well as middle-of-the-night lows and dawn phenomenon. I find the trend arrows and the angle of the line both rising and falling, to be invaluable.

Oh, and I have found that sensors fitted to my left arm are always more accurate than those on my right arm.
Bizarre, but true.

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Thanks Bruneria, I did wonder if the arm made a difference as the third one was fixed to my left not right arm.
I agree about not being too worried about the precision more the spikes - but the spikes its showing are a lot less on codefree and even its own blood tests - so maybe I'm not that well suited to it. it worrying that I have spent two weeks being quite comfortable that thing are progressing well and now feel like I've taken a massive step backwards which is annoying 1

well in his defence he had already sai hewould replace mine. I did wonder if h really meant a 15% range either side 30% in all.
Would that be close to the standards

Bluetit1802 said:

Are the rises post meal what you would expect. By that, I mean after a particular meal you eat often where you might go up by 1mmol/l on average according to your meter readings (assuming you have previous records of these post meal rises) Or are you going up more than expected, say by 2 or 3mmol/l - ignoring the actual levels.

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these readings were after eating nothing - went from mid 5 to 11.5 over about an hour, no food. I'm used to 5 goes to 8/9 during dawn phenonemon but this was a whole new range of high not backed up by finger pricks at all. ie. the fingerpricks were lower but the sensor just carried on getting even higher so nothing to do with the 15 minute gap either

Thanks
I've got a new one now and that seems to be coming in somewhere between the very optimistic one nd the very pessimistic one.
it doesn't really help that I've got bad case of late onset dawn phenomena - beginning around 9 am, but actually I seem to be able to eat lots of things in the afternoon including bread and potatoes and it doesn't even register.
I'm clearly perverse !

Brunneria said:

Not really. I have seen many references on the forum to type 1s adjusting their insulin ratios to suit different levels of insulin resistance during the day, and we T2s get it too. Both @bluetit and myself (and many others whose names I cannot instantly remember) have this too. It just means (for Bluetit, myself, and apparently you) that we are best avoiding carbs at breakfast.

The reality is that no simplistic assumptions suit everyone, and the more we learn, the more we are able to tweak our own diabetes management, whether that is with meds, diet or exercise.

I would also suggest that if you are regularly getting an increase in bg at 9am, that you look for another reason than Dawn Phenomenon. DP is usually considered to start around 4am, as your hormones adjust to the start of your day, and ready your body for getting up and about. You Libre will be very useful in identifying when and if you get DP, and what time it kicks in.

Unless you have a very different schedule from most of us (and are getting up around midday?) then there is probably another reason for your bg rise. You are in a much better position to work out what it is than I am but the possible causes that spring to my mind are; work related stress, exercise, coffee (apparently it affects some peoples' bg), commuting stress...

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My blood sugar is lowest upto around 8,00 am
I rise around 8.30, I don't work, I don't drink coffee, I don't commute, my exercise is only walking - and it doesn't seem to matter when I do it.
The only thing currently wrong is sleep quality - that has been a problem for a while,and then there was my accident ( I wake up every time I turn over.) The pattern of rising glucose in the morning hasn't changed pre and post accident. I've not been eating pre bed though I am trying to take note if I do if that changes anything . I'm fairly convincde its the dp and my cycle is just a bit out of whack , I did use to find getting up early a real problem when I was working and I rarely began work before about 11.00

Thats interesting , your symptoms sound just like mine ,. Hoever as it happens worse when fasting and trying egg maonaise for breakfast didnt stop it .
I will try the boiled egg only approach after xmas !