PDM meter reading lower than our AccuCheck meter

We just changed our son's CGM today so we started using the OmniPod PDM's meter just today. Just for the heck of it I had him test with the PDM AND with his AccuCheck this morning, at lunch, and before dinner. The PDM is reading 30+ points lower than his AccuCheck meter every time.

While I obviously like the lower reading, if it isn't accurate it's going to give us higher A1c numbers in the long run. I did a solution/control test on both meters and both results were in their normal range. So, now I'm nervous to keep using the PDM's results, but I realize that we need to for accurate bolusing etc.

Anyone know how accurate this PDM meter is supposed to be?? We went with AccuCheck in the beginning because it had a high accuracy rating.

It is common that PDM readings are way too low. My A1C was 1% higher than usual because I trusted the PDM. Don't make the same mistake.


I do believe that the Accuchek is more accurate than the Omnipod PDM, but my son is 3 and I don't mind that he runs a little higher. His A1C has always been in the 7's, which is fine, and we just adjust to the readings on the PDM. I know some people change the code on the PDM to 17 and they believe that it runs more accurate. I believe it does too but then I noticed my son running way lower in general than I wanted so I switched back to 16. It's all relative.

to be honest i have heard this but never really tested it, all meters should be slightly different but 30 sounds alot ... i am not going to start making grumpy teen test on two meters however, he has been on the omnipod for two years and he is relatively stable. how is it going otherwise? was he ok with the insertion, did you start the real insulin yet? let us know! hope all is well otherwise! amy

It's been discussed several times. Remember that when you compare two meters you are dealing with two sets of errors, so 30mg/dl could be one meter consistently reading 15mg/dl high and the other 15mg/dl low. In fact 15mg/dl is well within the accuracy limits of current standards and does, in fact, even meet the proposed new (2011) standards!

More important the accuracy of any meter decreases as the reading increases. In fact the manufacturers and the FDA typically quote a percentage accuracy, not an absolute one. At a blood sugar of 200mg/dl even a 30mg/dl error is just 15% wrong, and that is still within the current FDA guidelines for accuracy (+/- 20% - up to 40mg/dl wrong)!

The current standard is ISO15197:2003. While few people read ISO standards because of their enormous cost the current standard is documented here:


(You can also just Google for "ISO 15197" and look for the PDF file 120710-Hasslacher.pdf).

The accuracy of any meter is stated on the documentation that comes with it. As the above PDF documents meter accuracy is normally a lot better than the FDA standards, at least for higher readings. In fact when I've tested pairs of meters the consistent errors I've noticed have been below the variation in pairs of readings from the *same* meter. Particularly at high BG levels (above 200mg/dl) I see quite large differences (as much as 50mg/dl) between two readings done one after the other. I'm using a Contour USB, which comes out as pretty accurate in the Hasslacher tests and, indeed, 50mg/dl differences in 200mg/dl BG could be as little as 12.5% error (e.g. if the two readings were 175mg/dl and 225mg/dl).

John Bowler

Yes, I have found this for me as well. I changed the code on the PDM to 18 instead of 16 and it runs much more in line with the other newer meters I use (One Touch Verio IQ and occasionally Accu-chek Nano or Contour USB NextLink). Keep in mind that I did this with some testing with both control solution as well as real BG readings to see which code was a better fit for me. I know others who have changed the code to 17 or 18 as well, as mentioned in the link Helmut provided.

OK, I found my son's other/school meter (also AccuCheck) that he used to use and we have done 3 tests at once (with one finger prick). The two AccuCheck meters are consistently within 10 pts. of each other while the PDM is consistently 30-35 pts. lower. We're going to check one more time before dinner with all three meters and see what we get. Well, we go back to see his endo. tomorrow to start the REAL Pod without saline, so I'll talk to her and see what she says.