hbA1c and Freestyle Libre

[naughtyblackcat]

I don't get your comment about using your Libre for 50 - 100 times a day.
Do you mean you have been scanning it that many times and have calculated your predicted Hb1AC based on the value at the time of your scan?

The Libre sensor in your arm is regularly testing your BG based on your interstitial fluids (slightly different to the glucose in your blood but close). Unfortunately, I cannot find anywhere online which states how often it does this test. It stores the last 8 hours of results on the sensor. When you scan the sensor, you are downloading the last 8 hours of data. If you scan less often than 8 hours, you will miss some data because the sensor only have enough memory for 8 hours.

Back to my confusion around your 50 - 100 uses per day: you have more than 100 data points downloaded to your reader. If the sensor tests every 5 minutes, you have nearly 300 data points per day.

Apologies if I have misunderstood your statement. I find it frustrating that many people do not seem to understand the power of the Libre: it is in its history and trends not single point-in-time readings. Using a Libre as a replacement for finger pricking is like using a Smart Phone just to make phone calls. If the NHS is to get any value from prescribing Libre, I believe they should invest in some education of the users.

<Sorry, I didn't mean to hi-jack this thread for my soapbox>

Hi - to clear up the confusion, I'm scanning 50-100 times per day. I then download the information from the libre to my computer and the software comes up with an estimated Hb1AC based on the readings. You have cleared up some confusion though - namely that the sensor is regularly testing - I only thought it tested when you scanned. This explains why I am seeing results overnight that I do not recognise. Thank you for clearing that up.

 

[Diabeticliberty]

Hi - to clear up the confusion, I'm scanning 50-100 times per day. I then download the information from the libre to my computer and the software comes up with an estimated Hb1AC based on the readings. You have cleared up some confusion though - namely that the sensor is regularly testing - I only thought it tested when you scanned. This explains why I am seeing results overnight that I do not recognise. Thank you for clearing that up.

The sensors only hold data for the previous 8 hours so if you want a constant trace you really need to be swiping at intervals of no more than 8 hours. Mine wander below and above my finger prick meter. It's like a whopping big game of Diabetic Wheel Of Fortune. Sadly however I have never yet won a speedboat

 

[slip]

@Diabeticliberty just looking at those pictures, and I know they are fairly old if the date and time is anything to go by, but those graphs indicate a failed sensor, having flat red lines, and sharp drops and gaps does suggest this and I wouldn't trust the readings one bit and call it in to Abbott.

 

[naughtyblackcat]

FYI Metformin is not prescribed to lower blood glucose. Your numbers will have come down due to your change in diet and excercise regime. So, well done, keep it up.

Thank you! I certainly intend to.

 

[woodywhippet61]

@Diabeticliberty just looking at those pictures, and I know they are fairly old if the date and time is anything to go by, but those graphs indicate a failed sensor, having flat red lines, and sharp drops and gaps does suggest this and I wouldn't trust the readings one bit and call it in to Abbott.

Having flat red lines is't a sign of a failed sensor or if it was then the past 5 sensors I've used are all failed. It's normal for me. Red for me is 3.8 btw.

 

[Diabeticliberty]

Having flat red lines is't a sign of a failed sensor or if it was then the past 5 sensors I've used are all failed. It's normal for me. Red for me is 3.8 btw.

A flat red line is a reading too low for the sensor to read. A broken line suggests a read error. If you get a broken line and go into your sensor event log you will see a series of error codes. Ordinarily following an error the sensor will start recording and transmitting good data again. Sometimes they just die. It is not unusual to get fairly regular broken lines in the life of a sensor. The photo's I have posted show a broken line on a trace from a sensor that lived the full expected 2 weeks but gave incorrect readings. The others show incorrect readings without a broken line. Theses are just a random selection from many, many readings that have proven not to be accurate. This is why my predicted A1c and actual HbA1c are worlds apart. Just like Naughtyblackcats (MEOW MEOW!!!!! Sorry NBC but I couldn't resist that one) and lots of other users too

 

[slip]

Having flat red lines is't a sign of a failed sensor or if it was then the past 5 sensors I've used are all failed. It's normal for me. Red for me is 3.8 btw.

Ha! anything below 3.9 is displayed in red, as technically that is a hypo, the flat red line where it bottoms out means the reader has detected a reading below 2.2 - you won't be.....

diabeticliberty has just replied!

It's a pity you can't select data for the software to ignore when predicting A1c

 

[RFSMarch]

Was diagnosed T2 back in June and had an hbA1c of 67 mmol/mol (10.6%).

Just retested at my GP surgery and it's down to 42 mmol/mol (7%).

I'm absolutely chuffed and put this down to 500mg of Metformin twice a day, lots of exercise and reducing my carbs and sugars considerably.

One thing I was disappointed with though is that I've been using the Freestyle Libre for about 3 months and this was predicting an hbA1c of 32 mol/mol (4.9%). I've literally been using it 50-100 times a day, so have been really surprised that it is clearly testing so low.

Kind of makes me question the libre's effectiveness, other than to measure up and down trends.

Had it been 32 (4.9%), then I'd have considered dropping one of the Metformin tabs and continue monitoring with the libre - but now I'm thinking I should maybe keep to taking both doses and just drop the libre use, and wait for my next appointment with the nurse in March.

Anyone got any thoughts or advice on this?

I am almost on exactly the same timelines as you.
My hbA1C was 111, FBG was recorded at 18.5
Since getting the libre and stopping being so **** complacent about hitting the gym or at the very least adhering to the rehab sessions as I have no cartilage left in my knees, mine shoul have hopefully come down when I have my follow up bloods done this Friday.

If it helps - I look at my 90 day average BG to give me an idea of what to expect for hbA1c and I am outlooking around a value of 50 or thereabouts. Which I am quite chuffed about too but will wait until I get the real results before I allow myself a Snoopy dance of joy!

I look at my Freestyle Libre as a tool to help me reset, but I don't take it as gospel, but I have been looking at the Weekly and Monthly reports it allows you to print off and the Glucose Patterns which I will take with me to the GP when I get my results.

My GP thinks I have wasted my money on what he views as a toy. So it will be fascinating to see if his attitude changes if the results are what I hope for (eg lowered BG, lowered cholesterol and BP down from High to Pre-High).

Curious as to the using it 50-100 times a day. I scan a max of 15 times a day and I thought that seemed quite high!

 

[woodywhippet61]

I understand now, the lowest my readings have gone is 2.6 so I would not have had a red flat line.

 

[Dr_Russell_Payne]

Hi - to clear up the confusion, I'm scanning 50-100 times per day. I then download the information from the libre to my computer and the software comes up with an estimated Hb1AC based on the readings. You have cleared up some confusion though - namely that the sensor is regularly testing - I only thought it tested when you scanned. This explains why I am seeing results overnight that I do not recognise. Thank you for clearing that up.

Hi Blackcat, a friend and I are developing a monitoring and reporting service for diabetics. I am looking to get some anonomised blood glucose profiles. I came across this post and wondered if you would be happy to share your data with me? Apologies if this is in the wrong area. Russ

 

[Zilsniggy]

The Libre I feel is just good for measuring variance. First thing in the morning it correlated well with my regular readers.

I have posted previously how worrying the inaccuracies are. I think they should have a means of calibrating.

 

[Zilsniggy]

My libre is so inaccurate I have given up on it. If it's so good for marking trends I can't see the point of marking a totally inaccurate trend. With some sensors, this has been as much as 4 mmol difference!! I am finding that all the Freestyle is doing is making me check actual blood glucose readings more often, but I bought it thinking that i could reduce the amount of finger pricking......silly me! There is just too much variance It is an expensive piece of kit just to use to check trends, as this can be done from BG readings. I'm not a fan......

 

[barrym]

Just how I was feeling about Libre. I have 3 still here and Abbott had agreed to give me a refund, but I thought I'd try just one more.

Have done two comparison tests today and both just 0.1 different. Unbelievable!

Not sure if it's a good thing or not. If the next sensors are the same I'd be happy, but if not.....

 

[Squire Fulwood]

I looked up stuff about the sensor and I don't want to do it again but from memory it reads every 15 minutes for 8 hours when it starts to overwrite the first reading. If you leave it for more than 8 hours without scanning then you lose data.

 

[barrym]

I looked up stuff about the sensor and I don't want to do it again but from memory it reads every 15 minutes for 8 hours when it starts to overwrite the first reading. If you leave it for more than 8 hours without scanning then you lose data.

That's right.