Attack of the Meter - Preliminary Results


So I had the weird all-day appointment yesterday. They took a new a1c and blood from my finger 5 times throughout the day. A LOT of blood, too. Ouch. They filled these weird little cannula-like tube things each time with about 10 drops of blood (eek!) and I tested from the same finger with the Ascensia Contour (which I think is wrong) and the Accu-Chek Aviva (which I think is more accurate). I have an appointment with the doc next Tuesday for the results. All I know is that my a1c’s have not been matching my meter results at all. The meter to meter results are below. As planned, I purposefully under-bolused at lunch so that I would be around 170 to see the variance at a higher number!

Time… Ascensia… Accu-Chek…Variance
8:00 … 83 … 94 … 11pts
10:00 … 91 … 100 … 11pts
11:30 … 118 … 152 … 34 pts
14:30 …167 … 199 … 32 pts
16:00… 99 …132 … 33 pts

I should note I also tested several times myself between the official ones and the same 10 to 30 point difference showed up in nearly every test. If my a1c was based on this one day’s results, the Ascensia would say my average is 112 (a1c of 5.7%) while the Accu-Chek would say the average is 135 (a1c of 6.2%). Big difference in the long run.

And it’s interesting that this half of a percentage discrepency between the meters matches perfectly with my previous a1c experiences here. In May it “should” have been 6.8, but was 7.4. In August I said 6.5, but the lab said 7.0. The most recent one “should” be 6.3, but I’m pretty sure it won’t be! I can’t wait to see the lab results. Even if the meters are within the 20% range, it still makes a huge difference to me if in the end it causes an increase of .5% in an a1c!!! If the Ascenia tells me I’m at 118 after breakfast, I’ll be pretty satisfied with that, but the Accu-Chek said 152! That’s a whole 'nother unit of insulin! What do I go by?

I will post the results next week…

NOTE: Doc appointment postponed due to emergency. New appointment is the next Tuesday, September 18

The a1c is roughly weighted as follows: 50% of the number comes from the previous month, 25-30% comes from the 2 months prior to that and the rest from over 90 days ago. I’ve used the 50% (prior 30 days), 25% (30 to 90 days) and 25% (avg guess based on old a1c) formula for five years. This has worked pretty well. Back in the US when I used the Accu-Chek Active, my a1c calculations were within .1% of the lab each time.


You know what’s really awesome about the disparity you’re seeing? It’s in the same direction every single time. The accu chek is CONSISTANTLY higher than the contour, so you can plan for that. That second reading has a nine point difference, btw, not an 11 point.
Anyways, to get from the accu-chek to the contour reading, you’d subtract 11%, 9%, 22%, 16%, and 25%; I suggest that in practive using the aviva, you subtract 15% when you’re over 100 and 10% when you’re below that.


Well, it’s the other way around that’s the issue.

The Contour tells me my numbers are great, but my a1c’s are much higher than what it says. So we think the Contour is consistently giving us lower than actual readings. The Accu-Chek (which I just bought a couple of weeks ago because after the 3rd impossibly high a1c I suspected meter error) appears at this point to be more accurate. I have two months of Contour strips, so I’m ADDING 10 to 30 points (depending) to my Contour readings and bolusing accordingly. We’ll find out for certain which meter is closer (I will be totally shocked if it’s not Accu-Chek all the way) on Tuesday. If the Contour DOESN’T look that inaccurate, then something must be wrong with my hemoglobin because there’s a big discrepency for about 9 months now.


Oh, I should say that we know I’m not anemic, so that’s out. My primary care said nothing could be wrong because a standard blood count showed normal levels of hemoglobin, hematocrit, etc. Everything was normal. Is there something ELSE that can be wrong with hemoglobin that will NOT show up on a typical blood count? That’s the next thing to look into if the Contour meter isn’t giving me falsely low readings all the time.


Why are you even attempting to compare your average meter readings to your A1C? You can’t possibly be taking enough meter readings to even be able to approximate what your A1C should be. It’s the equivalent of trying to measure how far you’ve driven in a month by looking at your speedometer (NOT odometer) 4 times a day.

Compare your meter readings to the lab blood test result to see which meter is more accurate (as you are doing) and adjust your targets if your A1C is not where you want it.

My experience with 3 different Accu-chek Aviva was that they were all consistently higher than all 5 of my other lab calibrated meters (5 models by 2 different manufacturers) and significantly higher than a lab blood reading. The discrepancy seemed to be greater with higher sugar levels. I don’ t use Avivas any more.