A1C Decrease - Meter Correlation?

Yesterday I met with my endocrinologist for my quarterly appointment. My A1c at my last appointment was (I believe) 7.4%, a bit over 4 months ago. Yesterday's result was 6.7%. Now as estatic as I am, I'm trying to find the cause for the decrease so that I can keep it up! My BG averages per my meters and Dexcom were generally the same as they usually are - no big differences there. The only thing I can think of is that I was using the newer Verio IQ meter and changed the calibration code to 18 on my OmniPod PDM for my primary meters during this time. For me, these provide higher readings than past meters I have used. In my head I'm thinking that my average BG is around 145 mg/dL which this time correlates to the 6.7% A1c. In the past, although my averages were always around that 145 mg/dL, my A1c were always higher because my BG average wasn't really around 145 but higher. Is there a scientific reason this could really be what happened? I recall others stating they've also had a drop in A1c when switching meters. Thoughts anyone?

I've found it hard over the decades to correlate an A1C change with a change in my day-to-day control.

In fact when I feel that my bg has been most stable, I often find my A1C ticking up a notch. And when my bg has been most unstable (especially many hypos) my A1C goes down a notch.

This anti-correlation vs how I "feel about my control" vs "what someone might read into my A1C" is sometimes frustrating.

I'm lucky that my docs don't try to read much into every little change in A1C.

Despite what the medical establishment implies, the A1c is a rough and crude measurement. There is an effort to calibrate A1c measurements across industry allowing tests from different labs to be comparable and credible. The goal for 2012 is that the tests be within +/- 7% (see the NGSP). Thus a reading of 7.0% could be anywhere from 6.5 - 7.5%. Gosh, that would entirely explain your readings.

My experience is that there are also personal variations, if you have some anemia or other conditions, it can affect the readings.

In either case, you should celebrate your accomplishment. Pat yourself on the back. Who cares if part of it is explainable by "errors." We are still proud of you.

What shall we say the word "scientific" means? Having a newer meter probably provides closer results to true. I think. I hope. Maybe. Keep on doing what you're doing! Congratulations!

Thanks guys! I am overjoyed, believe me. I am just wondering since I don't want it to be a fluke like the last one under 7% I had. It's been a huge struggle for me to reach that goal so it's monumental to say the least. Oh and by scientific, I just meant a real possible explanation in terms of variations and things like that :)

A1c has a ton of variance. I work in the Laboratory field. I posted about this a while back but I'll give you the run down/
Even though docs will tell you that your BS readings at the time of the A1c test do not matter, THEY DO.
And a lot too.
You should try to keep your sugars at the same level when You get blood tests done or else it will be all over the map. I try to be as close to 100 as I possibly can.

I tested the 2 most common methods for a1c and on myself I tested at 85, and at 200.

The results were amazingly different and drawn less than an hour apart and nearly 1 full percentage different.

In any case tightening up your control is always good. If you are not having any Lows you can prob afford to tighten it up some more, maybe get it lower.


I am with everyone here who says celebrate your accomplishment. 6.7% represents an average blood glucose of 145 so you are right on as far as your meter goes. I went from 7.5% to 6.1% in 6 months and it wasn't due to a new meter, and the endo was not happy at all. I had a repeat one done a couple of months later to see if it was a fluke and that came back 6.4%. Since an A1C is not exact by any stretch of the imagination, and a good A1C can just be a matter of a bunch of highs 200's and a bunch of lows 40's you're still going to average 120. So as long as you are not experiencing too many hypos and you have all the new toys (Dexcom, Omnipod)then be happy. And celebrate but don't have too much ice cream.