Electrochemistry Impedance Spectroscopy has been proposed as a promising technique for non-invasive glucose monitoring. Although it is possible to find related literature to in-vitro and in-vivo experiments, no clear information is available regarding the precision of the measurements. In this paper, we address the problem of the precision due to different samples of the same sensor type and different sensor positions. We will show that the precision of the measurements is high for different sensor positions (over 96 %) but can drop significantly when different sensors are used (around 90 %), even when these sensors belong to the same brand.