hbA1c and Freestyle Libre

Yes your Libre is wildly inaccurate but don't feel too bad about it cos so is mine. I have been attempting to raise the predicted A1c point to the Abbott Cheerleadiing Troupe for approximately 2 years now and sadly they just stick their digits in their ears and talk really loud. My own predicted A1c reading from my own Libre is 34 my actual is 46. You may get some users suggesting that you are wearing the wrong coloured socks when you swipe your arm or not smiling when you apply a new sensor or maybe its the phase of the moon. I'm sure you get the general idea

naughtyblackcat said:

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.

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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>

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.

Of course the other side of the coin is there are many Libre users who say the Libre software predicted A1c is spot on!

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.

My sensors typically read lower than BG but the good thing is each one is generally consistently lower. Result is it's hba1c prediction is usually about 10% low. However the ability it gives me to bolus accurately and be confident has helped me lower my hba1c dramatically

Dear oh dear!!!!!!!!!!!!!!

Oh dear oh dear oh dear!!!!!!!!!

Oh ******!!!!!!!!!

Oh Blimey!!!!!!!!

I sometimes wonder if I'll run out out of terms of exasperation before I run out of mug shots?

Just to lighten the mood a little here a piccy of Dave my now long dead cat.

Maybe there is something wrong with our arms? I get readings a bit like this but not quite so different. Oh dear that's as clear as mud. BUT when I read others comments about out by .5 or 1 I do wonder if there is something wrong with my arms.

I've got my A1c coming up in a couple of weeks and I'm wondering what my results are going to be. Shame that it's not more accurate. But then are any of the monitors accurate it seems not.

woodywhippet61 said:

Maybe there is something wrong with our arms?

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I always feel and always have that there is an element of 'Emperors new clothes' with the whole thing. Having said that I do keep shelling out for sensors. The thing for me is it offers some respite from pricking my fingers 15 times per day which is where I was before I adopted it. They do however remain for me woefully inaccurate at times.

My one is currently running about 0.5 lower than normal so I would expect the HbA1C estimate to similarly be a bit off. One of the reasons I got it though was because I was concerned that I was missing spikes in my BG by doing finger pricking alone.

MySugr estimates my next HbA1C to be 34, down from 70. Will be interesting to see if the Libre thinks the same after a few weeks of using it. Either way, I'm remaining sceptical!

AlexMagd said:

My one is currently running about 0.5 lower than normal so I would expect the HbA1C estimate to similarly be a bit off. One of the reasons I got it though was because I was concerned that I was missing spikes in my BG by doing finger pricking alone.

MySugr estimates my next HbA1C to be 34, down from 70. Will be interesting to see if the Libre thinks the same after a few weeks of using it. Either way, I'm remaining sceptical!

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I don't mean to second guess you but I feel that a 0.5 difference would be fairly negligible. Regular finger prick meters have a tolerance of 0.5mmols with a 5.0mmol blood test reading.

Diabeticliberty said:

I don't mean to second guess you but I feel that a 0.5 difference would be fairly negligible. Regular finger prick meters have a tolerance of 0.5mmols with a 5.0mmol blood test reading.

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Totally agree! I think a lot of it is psychological though - I wouldn't bat an eyelid for 5.4 vs 5.9, but for some reason 4.8 vs 5.3 *seems* like more of a difference!

I'm still doing some finger pricking just to keep tabs on it. If it stays consistently low by about 0.5mml/l I'll be well chuffed

I wish that were the size of the discrepancies I get.

Yesterday I had 12.0/8.7, 8.2/7.1, 7.5/5.1, 4.1/3.3, meter/libre.

I bought 4 sensors two months ago and still have three left as they keep changing them. I keep telling them I don't want them swapped I want them right, or at least constant. I think it is always libre lower in the main.

Last swap I said I want a report on what if anything the lab finds on the returned sensor and I'm still waiting, but am told I will get something.

Today they offered to take the three unused ones back and give me a refund. But I don't want that. The convenience is what I want, but not at the expense of accuracy.

I have a LibreView account and an automatic upload to Diasend via their app and it gives me the ability to see every sensor reading's value, not just a graph.

It is a pretty comprehensive system and I love it.

It's just the inconsistency<scream>

naughtyblackcat said:

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?

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My HbAc1 is 97.4, but hopefully should be going down with the Metformin. I personally wouldn’t do anything without speaking to your nurse or doctor first.

Doctor told me I didn’t need to prick my fingers, and just do it when the diabetic nurse asks me to.

naughtyblackcat said:

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?

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Sorry I forgot to say well done on reducing the numbers. Personally I'd carry on using the Libre for monitoring the effects of what food you are eating. Well that's what I'm going to do. After my a1c test in 2 weeks I'm going to start experimenting with adding in some carbs. i.e. the odd potato or piece of toast. Well that's the plan.

Your Libre predicts you hba1c too low, (as does mine), but it's not as far out as you think. An hab1c of 42 mmol/mol converts to 6%, or an average bg of 7mmol/l. My last one was the same as yours, 42, an my libre predicts 31. Not sure what it predicted at my last test, but not much has changed, so I guess I'm still between 38 and 44. Any diabetologist will tell you that 42 is wonderful to anyone with diabetes, and although you'll find quite a few people on this forum with lower levels, most diabetics caught in the wild will be higher. On top of that, 42 is of course the answer to the ultimate question of life, the universe and everything, so I kinda like my number 42.

Antje77 said:

Your Libre predicts you hba1c too low, (as does mine), but it's not as far out as you think. An hab1c of 42 mmol/mol converts to 6%, or an average bg of 7mmol/l. My last one was the same as yours, 42, an my libre predicts 31. Not sure what it predicted at my last test, but not much has changed, so I guess I'm still between 38 and 44. Any diabetologist will tell you that 42 is wonderful to anyone with diabetes, and although you'll find quite a few people on this forum with lower levels, most diabetics caught in the wild will be higher. On top of that, 42 is of course the answer to the ultimate question of life, the universe and everything, so I kinda like my number 42.

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With the greatest of respect my predicted A1c of 34 is 12 points away from my actual HbA1c of 46. Regardless of how good or bad or indifferent my actual laboratory test is my Libre is still 12 points out and that in my book is too far out. If my finger prick test was giving me discrepancies of this magnitude and I do cross check my finger prick meter with control test solution and against a second meter then Roche Diagnostics would be getting the same bad rep from me that Abbott get. I cannot comprehend how it is that loads of us just blindly accept what the thing says like sheep.

By the way Antje77 I don't mean you in this. It is just that I was replying to your answer

Diabeticliberty said:

With the greatest of respect my predicated A1c of 34 is 12 points away from my actual HbA1c of 46. Regardless of how good or bad or indifferent my actual laboratory test is my Libre is still 12 points out and that in my book is too far out. If my finger prick test was giving me discrepancies of this magnitude and I do cross check my finger prick meter with control test solution and against a second meter then Roche Diagnostics would be getting the same bad rep from me that Abbott get. I cannot comprehend how it is that loads of us just blindly accept what the thing says like sheep.

By the way Antje77 I don't mean you in this. It is just that I was replying to your answer

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Thanks for the last line, I started getting worried
Just too make sure, I said it was less far out than naughty black cat thought because his post stated his a1c was 42 (7%). 42 equals 6%, so he might be doing better than he thought