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converting meter readings to HbA1c

S

Spiral

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http://www.diabetes.co.uk/hba1c-to-bloo ... erter.html

I found this very useful tool a few weeks ago. Since I started testing and adapting my diet I have seen my levels steadily falling, and this has included a lot of tests in my highest spikes, - about 1 hour after eating. My average readings have been a higher over the last couple of days, so I was a bit concerned about what this does to the average.

I will be having another HbA1c at the end of this month, and so converted the highest of the average readings, 6.2mmol/L, as well as the lower reading of 6 on my meter using this tool and both came up with an estimated HbA1c of 6%. I am expecting something a lot closer to 6% at th e next "official" test.

Then I wondered what my average needed to be to get under 6%, so I converted 5.9% to a mmol/L reading and got 6.111111111. The result seemed to be higher than the average readings I put in :?

Is this not a straight forward conversion? There seemed to be a bit of a discrepancy in the converted readings.

What about the rest of you? Have you used this tool and how accurate was it for predicting your HbA1c?
 
The problem,Spiral ,is that your finger prick test is a record of your blood at that point in time.The Hba1c takes an average percentage over 90 days of glycated blood.So if ,for instance ,you have 'spikes' during the day that you are not aware of then these will reflect in the Hba1c causing the percentage to be higher than you calculate.
 
calculators vary too.
If you put an average 4.8mmol into the calculator on this site it gives an Hb A1c of 5%, the ADA calculator which takes into account recent research gives 4.6%. As Sue says it doesn't really work very well that way round as your levels will rise and fall without you necessarily taking a reading. (mine goes down, up, down over nights but most nights I don't actually test at the highest point)
Nevertheless I use a piece of software that has always got my Hb A1c correct. (Sidiary). I've no idea how it does it but I'm sure it needs lots of readings to be accurate.I test a minimum of 4 times a day, but very rarely this few and often far more ( including early morning check). Luckily I get prescribed 50 strips a week (and even then I have occasionally bought my own to supplement)
 
I am doing 6-8 tests a day, sometimes more, and I'm aiming to pick up my spikes and manage my morning liver dumps a bit better. So I'm fairly confident I have the full range of my BS readings.

I know the HbA1c is an average and that a "good" HbA1c result may not pick up on some of the unacceptable spikes that cause the damage.

My question was in relation to the accuracy of the calculator on this site, because the results it gave me did not seem consistent.

When I converted my average reading of 6.2 mmol/L to an HbA1c, that reaings was 6%
When I converted 6% HbA1c to mmol/L it came out at 6.3 - higher than the number I put in to start with.
When I put in 5.9% (to establish what average I would need to get to that level) it came out at 6.1111111mmol/L
When I converted 6.11111111mmol/L back to an HbA1c, it came out at 6% :?

try it with your own numbers - do the calcualtion both ways (mmol/L to HbA1c and vice versa) and you will see what I mean about the inconsistent results. Unless it really is just me :wink: :roll:

The numbers churned out by the calcualtor appear to have a very wide margin of error. I wanted to know if anyone had used the software on this website to estimate their HbA1c and how accurate the tool on thi website is, rather than the methodology behind the HbA1c and fluctuatiuons in the BG over course of a day. Sorry if that wasn't clear in my original post.

I have not yet managed to get my meter to connect to the program that came with it, so we will see how accurate that software is when I plumb it in.
 
I find that calculator confusing because if you put in a whole number in the mmol/l it converts it to a mmol/mol Hba1c!!If you put in a decimalised number it converts to an Hba1c %.
 
Spiral said:
When I converted my average reading of 6.2 mmol/L to an HbA1c, that reaings was 6%
When I converted 6% HbA1c to mmol/L it came out at 6.3 - higher than the number I put in to start with.
When I put in 5.9% (to establish what average I would need to get to that level) it came out at 6.1111111mmol/L
When I converted 6.11111111mmol/L back to an HbA1c, it came out at 6% :?
Click to expand...
Just to through another spanner in the works so to speak, don't forget that most meters work to a tolerance of 10% + or - so a reading of 6.0 could be out by .6 either way :D
 
Spiral said:
sugarless sue said:
I find that calculator confusing because if you put in a whole number in the mmol/l it converts it to a mmol/mol Hba1c!!If you put in a decimalised number it converts to an Hba1c %.
Click to expand...

Phew! So it is not just me.
Click to expand...

Yeah that threw me for a loop too. :shock:
 
Sid Bonkers said:
Spiral said:
When I converted my average reading of 6.2 mmol/L to an HbA1c, that reaings was 6%
When I converted 6% HbA1c to mmol/L it came out at 6.3 - higher than the number I put in to start with.
When I put in 5.9% (to establish what average I would need to get to that level) it came out at 6.1111111mmol/L
When I converted 6.11111111mmol/L back to an HbA1c, it came out at 6% :?
Click to expand...
Just to through another spanner in the works so to speak, don't forget that most meters work to a tolerance of 10% + or - so a reading of 6.0 could be out by .6 either way :D
Click to expand...

Worked that one out. I have 2 meters, the Accu-check Aviva that Roche sent me and the Contour I "won" from the competition at the top of the page. I tested at the same time from the same drop of blood - 0.4mmol/L difference :|

I plan to take them both with me when I have my next fasting test at the surgery.
 
Spiral said:
I plan to take them both with me when I have my next fasting test at the surgery.
Click to expand...

I did exactly that at my last blood test and my Aviva was spot on, although I have no way of knowing if it is accurate at all levels all of the time. My competition prize contour always reads slightly higher. I generally use the Contour for my after meals tests as I pay for my own strips for the Contour and as it reads slightly high it helps my keep my after meal readings down, I mean if I get an on target reading I know it will be well within range as it reads high :D
 
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