It's seems like the reading comes out lower then I feel it should every time... Sometimes very shortly (about the 20 minutes it recommends not drinking or eating before using) after I drink (albeit, not very much) it will already read 0.
Had to purchase this as a replacement as we were told that our first one we bought 5 years ago could not be calibrated any longer. Our new one takes longer to give a reading, the tip is not as stable and it does not start to register until about 4-5 where our old one would start to register right away.