Nav vs Dex leading to... Onetouch vs Freestyle
OK, so this is weird.
I would never have seen this otherwise, but last year when I got the Dex I was also forced to switch my meters from the Freestyle Flash to the One Touch Ultra (because the Dex would only calibrate on the latter).
Then I got the software update for the Dex that would allow me to use any meter, but I had a bunch of left over strips for the OT so I kept using that for calibration, eventually aiming to switch to the much more user friendly Freestyle.
However, when you're wearing a real time monitor, strip use is very much lowered. I used to prick my fingers 12-15 times a day; with the Dex it was 4 or so, with the Nav even less (because it does not require the mandatory 2 calibrations a day, plus it seems more accurate overall). So I'm still using the OT for non-calibrations, and the built-in Freestyle in the Nav for calibrations.
But I've been running a little low recently - back injury put me in complete bed rest for 3 days, no appetite, very little food - and I had the occasion to use both finger meters at once so validate the Nav. I've never done this before.
Here is something odd. The One Touch consistently gives lower results than the Freestyle, and obviously the Nav (which calibrates off the FS). I just did this - Nav was showing 113, Freestyle 103, and One Touch... 67. It didn't feel like I was hypoing, but now I'm a little confused. This is not the first time either. So just how accurate are those finger stick meters? which one do I believe?
Well, actually, I suspect I know the answer to this one. One thing that has bothered me significantly since I started on the Dex was that my A1C's were consistenly higher than what the Dex and the One Touch indicated they should have been. I ran some analysis and the difference was consistent, at between 0.3% - 0.5%. Say I came into the doctor's office expecting an A1C of 6.7-6.8 (based on the results from the CGM and the overall average on the OT), and it would come out at 7.1 - 7.3. Even taking into account the depreciating effect of blood sugars on A1C numbers - that is, that more recent results count for more than older ones - it still didn't correlate. This was a major annoyance for me because over many years, my meter average usually ended up close to the A1C, due to testing so often through the day. It would occasionally not work but I would know that in advance, because I would have had a major overall change in blood sugars in the week or two before the A1C test (say, due to rapid weather changes).
But now I can venture a different guess - that the OT was reporting lower numbers than reality, consistently. That's a little scary come to think of it. How would anybody know? I don't know of anyone who actually runs a control solution test on a regular basis; I never needed one, and my meters have always seemed fine and tracked well to A1C's. The next few months will shed much more light on this, but it seems like I may have been led astray by the OT meter.
Confusing, to say the least.
I would never have seen this otherwise, but last year when I got the Dex I was also forced to switch my meters from the Freestyle Flash to the One Touch Ultra (because the Dex would only calibrate on the latter).
Then I got the software update for the Dex that would allow me to use any meter, but I had a bunch of left over strips for the OT so I kept using that for calibration, eventually aiming to switch to the much more user friendly Freestyle.
However, when you're wearing a real time monitor, strip use is very much lowered. I used to prick my fingers 12-15 times a day; with the Dex it was 4 or so, with the Nav even less (because it does not require the mandatory 2 calibrations a day, plus it seems more accurate overall). So I'm still using the OT for non-calibrations, and the built-in Freestyle in the Nav for calibrations.
But I've been running a little low recently - back injury put me in complete bed rest for 3 days, no appetite, very little food - and I had the occasion to use both finger meters at once so validate the Nav. I've never done this before.
Here is something odd. The One Touch consistently gives lower results than the Freestyle, and obviously the Nav (which calibrates off the FS). I just did this - Nav was showing 113, Freestyle 103, and One Touch... 67. It didn't feel like I was hypoing, but now I'm a little confused. This is not the first time either. So just how accurate are those finger stick meters? which one do I believe?
Well, actually, I suspect I know the answer to this one. One thing that has bothered me significantly since I started on the Dex was that my A1C's were consistenly higher than what the Dex and the One Touch indicated they should have been. I ran some analysis and the difference was consistent, at between 0.3% - 0.5%. Say I came into the doctor's office expecting an A1C of 6.7-6.8 (based on the results from the CGM and the overall average on the OT), and it would come out at 7.1 - 7.3. Even taking into account the depreciating effect of blood sugars on A1C numbers - that is, that more recent results count for more than older ones - it still didn't correlate. This was a major annoyance for me because over many years, my meter average usually ended up close to the A1C, due to testing so often through the day. It would occasionally not work but I would know that in advance, because I would have had a major overall change in blood sugars in the week or two before the A1C test (say, due to rapid weather changes).
But now I can venture a different guess - that the OT was reporting lower numbers than reality, consistently. That's a little scary come to think of it. How would anybody know? I don't know of anyone who actually runs a control solution test on a regular basis; I never needed one, and my meters have always seemed fine and tracked well to A1C's. The next few months will shed much more light on this, but it seems like I may have been led astray by the OT meter.
Confusing, to say the least.
posted by Blinkered at 4:38 PM
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