Anybody notice this with theirs? It the middle BG ranges up to around 150, my PDM BG reads 10-20 points lower than either my Accucheck Aviva or the standalone Freestyle meter that came with the kit. I'm checking my basals so I check practically every two hours, sometimes more, and it's a pretty consistent difference.
The difference falls to below 10 points under for readings under 80, so it's not much of a concern when it comes to hypos, but it's still a bit of an annoyance.
How are you conducting your studies? Using the solution, or using real blood? And if you’re using real blood, are you distributing it out of one finger stick (so all one pool of blood), or are you poking multiple fingers? I only ask b/c if you draw all from one pool, it could be that as you apply the blood you are actually concentrating the glucose molecules in the remaining blood, so w/ each strip that it’s administered to, it’s going to read slightly higher than the last b/c there is less “other stuff” floating around in there. What order are you applying these drops (i.e., PDM first, other meters second and third?).
Granted there is likely to be some variance, but if it’s consistently off, it may be the testing method…or may just be the meters! 
I have never noticed this before, but I will be checking now! Thanks for the info!
Hey Bradford,
I’m using whole blood readings with fresh pokes from multiple fingers, washed hands each time. At first, I was just using my trusty accucheck to log my BG, and using the BG from the PDM because it was fun to play with. I never actually planned to use the BG meter from the PDM for various reasons.
I noticed the trend after a few tests using the meters in that order, Aviva first then PDM. I got curious so I added the Freestyle meter, third, using the same container of strips. PDM always lagged 10-20 points behind while the Aviva and Freestyle meters had closer readings, with one being a few points different than than the other in random orders. I got really curious and changed the order of the meters with the PDM first, Aviva second, then the Freestyle. Same trend. I went to a different batch of strips, same code for the PDM and Freestyle. Same trend. I tried a new batch of Aviva strips, same trend.
Pretty consistent, but it could definitely be an artifact from my meters or the way I’m testing.
I’m curious if anybdy else noticed the same thing, or if it’s just me. =P
Cool! Keep me posted if yah will!!
No I don’t think it’s just you…I’m pretty sure others have mentioned this before too. So don’t feel alone It sounds like you’ve done a good job trying to eliminate all of the variables, so at this point I’d say it’s probably that the PDM reads lower (for whatever reason). I’m pretty sure the same technology is used in the PDM that’s in the freestyle meters (at least in the old flash and freedom meters…maybe not in the new lite and freedom lite? not positive though).
Maybe it’s part of that “FDA-allowed +/- 20% variance” :-/ …Or maybe someone else has some answers that will help us get to the bottom of this
Just tested, and YES! the pdm was about 15 pts lower! I have no explanation, sorry!
From the same big blood drop: Freestyle Flash: 111, PDM 106. Close enough.
Ok!
Thanks Steve, Bradford and Helmut. I don’t know if any you remember that old 80’s movie Blue Thunder, where Roy Scheider’s character checks his sanity with a stopwatch? Apparently I check mine with my BG meter. =)
The first day I got the OmniPod system, I checked it against my FreeStyle (Freedom) meter; the PDM was almost always 15%-20% lower (more in the lower range below 80). Curious, I ran a 3-way comparison using my spare meter (a FreeStyle Mini). The Mini gave results almost identical to the PDM, so if anything, I suspect the Freedom readings are slightly too high. I’ve been using it for several years now, so it may have aged a bit.
a.f.a. methodology goes, I don’t have control solution to test against (since the allowed variation is >20%, I consider it useless; in the first few years of using Freestyle meters I never saw an out-of-spec reading, and the local rep said they don’t think it’s worth bothering with), but I always used the same drop of blood from the same prick which IMHO should yield the same result (I applied the drop within 2 secs to all three meters, and varied the order randomly; I also tried this with sticks from 3 different batches.
FHS…I can tell, you are nutz.
Is there anyway to know which meter is the accurate one? One is higher and one lower so which one do you think is right…I’ve always used a freestyle light and when compared to the PDM its usually less than 5 pts apart so wonder if this is a difference in the makes. Do know that when I’ve had a number I didn’t think was right I would re-test with another strip from the same meter and make and be 5-10 pts different. Think it’s going to change even if you tested with the same meter from the same blood sample.