Harmonizing Glycated Hemoglobin Testing or HbA1c New Method

Harold · #1 (**permalink**) 09-30-2008, 08:19 AM

This came up in another thread causing some confusion. Apparently some labs around the world have started reporting HbA1c's according to a new standard determined by The International Federation of Clinical Chemistry Working Group (IFCC-WG). The DCCT/UKPDS range and numbers that we are all use to using run higher than the IFCC range and numbers. Placed a LINK, titled NGSP, to a PDF file on the NGSP site in the Resource Directory under Diabetes explaining the relationship. There is a formula and a chart for converting along with a graph for a quick view.

IMHO we will need to state which standard our A1c is given in our post and signatures. Example; 7.0/DCCT for the older standard or the equivalent 5.4/IFCC

morrisma · #2 (**permalink**) 09-30-2008, 09:18 AM

It wasn't enough we need to multiply or divide by 18 to compare BGs. Now we have to first, find out what A1c standard we are measured against and then convert to compare those too.

Another case of Entropy. Things really should get simpler not more complex....
Mike

volleyball · #3 (**permalink**) 09-30-2008, 09:38 AM

Oh good, my A1c just dropped

TomB · #4 (**permalink**) 10-01-2008, 12:00 PM

Harold,
This reminds me of "Who's on 1st, What's on 2nd and I don't know's on 3rd." I might have to do more checking on A!C variations. I had a blood test in June, 2002 that came back with "A1C = 6.1% corresponding to a mean of 117 mg/dl." I converted that 6.1% to 141 mg/dl and used that as part of a claim I submitted to the VA to establish a diagnotic date for DMII. I'm aware that A1c shouldn't be used to make a diagnosis but I'm trying my best to do that anyway. Your thoughts?
Tom

Harold · #5 (**permalink**) 10-01-2008, 07:06 PM

Typically it takes 2 test a month or so so apart to get a DM diagnosis. It use to be a fasting reading over 140, an A1c at or over 7%, and/or failing a GTT a month after one of the other two would do it. Now the 140 has been reevaluated down to 126 and a fasting over 100 but less than 126 will get you a Pre DM diagnosis. That was or is typical, the exceptions being a fasting reading over 200 or an A1c over 8 will get you a congratulations you have Diabetes!

As far as I know, and my labs came back this week with an A1c of 6%, labs in the US are still giving the A1c/DCCT out using the old calibration method for their equipment.

slipperyelm · #6 (**permalink**) 10-05-2008, 07:55 AM

I had not heard this. Thanks for the links.

MikeJsimon · #7 (**permalink**) 03-09-2010, 02:24 AM

Lets be clear this is only a consideration for the diagnosis of Type 2 diabetes. I am in agreement with the more cautious approach of Dr Bloomgarden — are we saying that it needs 2 separate measurements x weeks apart as with FBG or OGT? (dangerous if it is Type 1!) Do we know what happens to HbA1c values in children who often have transient high blood glucose values after stress such as convulsion or treatment for Asthma with Salbutamol and /or steroids? I would still stay with the overall assessment of the child rather than attach a diagnosis on the basis of an HbA1c.

ShottleBop · #8 (**permalink**) 03-09-2010, 06:40 AM

The new ABA recommendation to diagnose T2 based on an A1c of 6.5 requires only a single reading. The A1c is, very roughly, a three-month rolling average of your BGs; requiring two readings long enough apart might delay treatment unnecessarily. (IIRC, the A1c is in addition to, and does not replace, the FBG and OGTT as alternative bases for diagnosis.)