My "What the..." A1C

So my last several A1Cs have been 5.9 (last one 6 months ago) and I didn't feel anything had changed significantly so was accepting another similar one. It is 6.9!! I checked my averages: 30 days - 125, 60 days 123 and 90 days 120. According to the translation I have 6.0 is 126 so how the heck did I get a 6.9 which is about a 150 average??

I know I've read about it mattering what you are at testing so my fasting that day was 98, but by the time I got home from the lab and was ready for breakfast I was up to 138. How did this happen? Could it be wrong?

Do you use a CGM? Do you test overnight? Maybe you are missing highs somewhere?

I think the correlation between a1c an average bg is far from perfect… Certainly higher average bg = higher a1c and vice versa but I tend to dismiss the notion that it is a direct and repeatable mathematical equation… And in reality the estimate you had from your averages was within 1% point, so that’s probably about as close as we can expect from average bg readings

That would be a lot of highs to average out that much higher! But I was having a problem with high fastings until about 2 weeks ago when I pressed some magic basil button and now have excellent morning numbers. I guess it could have started rising during the night. I absolutely do not want a CGM and couldn't get one even if I did now that I'm on Medicare. I usually don't test during the night because I'm kind of neurotic about sleep and if I do wake up don't want to increase my alertness to test and risk not falling asleep again. But I guess I should try doing a couple tests during the night when I wake up anyway. (Though maybe the problem is solved with the better morning numbers). Thanks, Jen, Makes sense!

That makes sense, but I test about ten times a day, including post prandials. But Jen hit the nail on the head which is the one time I rarely test is overnight.

Hi Zoe. Having worked in and managed laboratories my whole career, I would first question the accuracy of the A1C result. Even the best labs can produce incorrect numbers.

Thanks, Mark. I live in a very small town with a hospital with a very questionable reputation, so...

I actually just perused the labs a bit more and saw a glucose of 164 which is weird because I was 98 shortly before the labs when I got up (I'm 5 minutes away) and only up to 138 by the time I was ready for breakfast after doing a couple errands in town.

You're welcome. Do you know what I would do? Forget it. I know you want to know what went "wrong", but for some things there is no answer. If your next scheduled A1C is elevated, then is when I would dig deeper.

My thoughts exactly!

I have been having a helluva time w/ DP lately, very ephemeral, in that a whiff of insulin will blow it away but it’s hard to deal with. Maybe the higher BG corrupted the reading? Another thing I wonder about is how I would tell if my meter fried out. Sine I calibrate the CGM off the meter, it’d be calibrated off too? It’s a tangled web.

Nope, not gonna go there! Basically my meter numbers seem to make sense (relate to expectations and be very close if I test close together, etc) so I just take it on faith. It is weird that I had a 98 fasting before leaving for the lab, then was up to 138 when I got home about an hour later - gotta wonder where the darn 164 came from?

Have you switched labs? I heard that you should always do your A1Cs with the same machine, as the results can vary from lab to lab...
Forget about it and just keep on doing what you have been doing for the past months, an a1c of 6.9 is still great ;)

Do you have more than one brand of meter/strips at home? Or can go pick up a cheapie store-brand meter and strips? I generally find my meter reading (taken right before or after the blood draw) to be within 5 percent of the lab, and I've never found it more than 10 percent from the lab.

A man with one clock knows what time it is. A man with two clocks is never sure.

The best in class labs meet a standard of +/- 7% which turns out to be about the variation you saw. Also, lots of things can affect your A1c, if you had been slightly anemic but had improved that would increase your A1c. It is also possible that the lab was just wrong, contaminated or use miscalculated equipment. In the end, the A1c is just one more mostly flawed measure of how we are doing. I actually trust my meter more than my A1c.

I actually trust my meter more than my A1c.

Since I test 10 or more a day, if you're like me, I guess we have to trust it more.

If (and that's a BIG if), your meter was accurate @ 138, then a 164 (using the same meter and test strip batch) would have been within the 20% range of error for at home meters. FYI - 138 + 20% = 165.6

I find myself doing two tests when I get a reading that is significantly different than what I would expect or different than how I am feeling.

A few years back, I had this series of A1c's:

6.7% Mar-2011
6.6% Jan-2011
6.0% Oct-2010
6.8% Jul-2010
6.6% Apr-2010

The October, 2010 result is not credible to me. There was no appreciable change in my treatment plan or lifestyle to justify a drop from 6.8% to 6.0% and a return to 6.6%.

As others have already stated, there can be many reasons for your recent result that have nothing to do with your overall BG control. You are mindful of your eating, exercise, and insulin program as well as doing abundant fingersticks. I would consider the 6.9% result an unrepresentative outlier unless and until subsequent A1c's confirm this number.

I went to the lab for an A1c last week. My BG was high at the time, two fingersticks were 167 and 194. My overall control over the last three months was very good. My meter and CGM both listed my 7-day average at 114 and 30-day average at 113. The 30-day CGM time in range, 70-140, was 77%. I'm curious to see if the high BG at the time of the blood draw has in inordinate influence over the result.

In the end, the A1c is a number subject to many flaws. Maybe we should append all A1c's with an "-ish" suffix!

Like Brian and Diabetic Dad, I let my meter be my measure of management. The A1c is for the birds. Or rather for the doc and to publish on the DOC. I dropped out of the A1c competition a long time ago.

Thanks everyone. I know it's just a number and I don't do it for anyone but myself; but it does feel like a validation for all our hard work. I guess I got spoiled by all those 5.9's and felt that was Zoe's official A1C number! I will maybe keep an eye on those overnights as Jen suggested, but otherwise just move on and see what the next one brings.

You will always be a fiver in my eyes.