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HBA1C VS 90 day BG averages on your glucometer

thanks Robert... i know i can use the convertor but what Im wanting to know is ... (example) your HBA1C is 5.9%, so is you 90 day average on your glucometer roughly 6.9?
 
although if you've had a lot of hypos, they would affect your 90 day average on your meter, but not your HbA1c - you can't un-glycate your haemoglobin... there is no cheating ;)
 
would be cool to know your HBA1C and also your 90 day average if that is ok?
The reason why I ask is this.. My 90 day BG average on my Glucometer was 11.2 which should give me a HBA1C of roughly 8.7% but my last HBA1C was 11%. (3 months ago)
I have been working so hard on getting my levels down and am having my HBA1C on Tuesday as Im going on a pump. My current 90 day average has now dropped to an average of 9.2 so Im hoping for an HBA1c of 7%.... :D
 
My last 3 months meter average is 6.3

I am having bloods taken on Thursday for HbA1c so will let you know what it is in a couple weeks when I've seen the nurse for results. The calculator says 5.6%
 
OK... here's a bit of forensics work from my diabetes app ;)
The 3 month average BG running up to my last HbA1c was 7.0.
Chart says my HbA1c would be 6.0 and the real test gave me 5.9 so not too far off.
 
The average BG and HbA1c are not directly related. The HbA1c is directly related to the exposure that red blood cells have had to glucose. If you were to look at a line graph of time on the x-axis and BG on the y-axis, then the area under the line (called AUC, or Area Under the Curve in the pharma industry) is what is directly related to the HbA1c.

Average BG is only loosely related. Using the median would be a better measurement, it's what I do in my day job of measuring AUC for oncology drugs, but for some reason machines only calculate the mean. Spikes in BG will cause more damage to the AUC, but less damage to your average BG. Also, everyone has differences in the lifetime of their red blood cells, which affect HbA1c values too. My latest HbA1c was 6.1%, but my average BG was 6.4 mmol/l. Compare this to Robert who had a higher average, but a better HbA1c.

Also, the error in the HbA1c measurement is normally around +/- 0.2%.

The best thing is to reduce variability, a steady BG level in single figures will give you a good HbA1c, whereas one with high variability, but the same average will give a worse HbA1c.

Sorry for the essay!
 
No probs! A quick google shows that pre-clinical (on rats) trials have shown that it lowers HbA1c. Clinical (on human) trials have been declared, but I looks like the results haven't been published, at least my quick google didn't show the results. It's not clear, however, whether it has a positive affect on BG control, or whether it decreased red blood cells' lifetime.
 
If you are 'average' and test enough to produce a meaningful average then the calculators seem to work quite well but not everyone is 'average' and may find their HbA1c is much higher or lower than expected,
First whether your calculated average is a true reflection of your glucose level is dependent upon how many times a day you test and when you test.

The formula used in the calculators is one that was derived from a recent study for converting an HbA1c to an estimated average. (ie not for converting average glucose to HbA1c). In this study they used continuous monitoring.
Some countries are putting this figure on blood test results sheets. The UK organisations decided not to do this .

In a letter to Diabetes Care, 2 British docs (Kilpatrick and Leslie) point out reasons why the estimated average may be misrepresentative for some people.
The study included people without D but excluded people with D and complications (ie a significant proportion of the diabetic population). It also didn't include people from several ethnic groups, children or pregnant women . They point out that we already know that these things affect HbA1cs.

There is also a matter of individual variation, they say
That uncertainty is such that two patients with the same true mean glucose level of 170 mg/dl could have an A1C value anywhere from 6.5% (snip ) to 9.0%.
Click to expand...
http://care.diabetesjournals.org/content/32/1/e11.long
 
Interesting post, as ever, from Phoenix. Sw11Bloke, take a look at a forum post I made a while ago about the weighting in HbA1c measurement: viewtopic.php?f=1&t=42836&p=391554&hilit=+what+your+hba1c+actually+means#p391554

In summary, around half of the HbA1c measurement comes from the most recent month and around 8% comes from the previous week. So don't do anything naughty when your close to your HbA1c as it will make the results look worse than had you been naughty 2 months previously!
 
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