Question about comparing meter numbers

I will freely admit that I obsess about numbers, so maybe that is why this is bothering me so.

We have 2 freestyle Lite meters. One is for use at home, so it gets used over 90% of the time. The other is the one we use when we are away from home. I started noticing that when we were away from home, P’s numbers were higher than when were at home. So I did an “experiment” of sorts. Using both meters I tested at home and then again using both meters I tested while we were out. TO make other things equal I used strips out of the same bottle. In test at home before breakfast - there was a 22 point difference in the 2 meters, of course the meter we use when we are out was the higher of the 2. I also did a test with control solution and there was a difference of 24 points (both within the control range). I tested when we were out before lunch and there was a 31 point difference in the 2 meters.

So I guess my questions

  • Is this normal?
    -If so which is correct? Or which should I go with since a difference in that amount could effect how much insulin we give?
  • Am I crazy to consider getting a 3rd meter to check these 2?

I do plan to ask at our next Dr. appt later this month, but I was just curious if anyone else had encountered this issue.


Yes it is very normal. My sons home meter tests around 20 lower then the doctors meter. I believe the accuracy of meters can be + or minus 20. It is very frustrating because a 70 reading at home we would treat as a low, where as if that reading had been done in his doctors office it would have been in the 90s. The same goes with his school meter.

To be honest I remember from this site about a year ago they asked for log into the FDA and complain about meter accuracy. The current standards were that meters had to be within 40 points plus or minus. Which in my opinion is a joke. 40 points can really change how I am going to treat my daughter. Our endo’s office states that although it is good to collect more than one meter to try to use the same meter all the time. It is their belief that even with the variance in meters that using just one will at least give you a standard or base line to always work with. Hope this helps.

I did a similar test with the new Bayer Contour meter and our usual One Touch Ultra II. The Countour was consistently 40 to 50 points lower and occasionally up to 100 points lower! That is huge! I tested them both with the solution before I did the experiment and they were only 3 points off with the Countour being lower. What the heck?? Which one is right? How on earth can I know how to treat my child’s blood sugars without accurately knowing what they are?


i had called our diabetes educators a couple months ago with this very question. we are in canada, so our numbers are different, but she told me that the meters can have a 10% variance from lab results (I am pretty sure it was 10%, may have been 15). I was having issue with a high reading, say 16, then retesting to make sure he is high then getting say 19 or 20 and not knowing what to correct for. she told us likely it is somewhere in between if one reading was 10% higher and the other lower there can be quite a difference between them, especially at a higher number. I also had some issues where he had been high and then it looked like he was coming down say 45 minutes later only to be back up half hour after that. i then started double testing when he was high with my husband’s (different type of) meter and was getting different numbers each time. She advised me to stick to just one meter and to wait 2 hours after correcting to check lest i make myself crazy. I have for the most part stuck to this advice and things have been going much better (we were also quite new to pumping at the time so i was worried that the site was bad after experiencing a couple sites that had gone bad).