Breath analysis is a non-invasive procedure to detect and monitor diseases and it is particularly attractive for patients who have to routinely check biomarkers, such as diabetics (blood glucose) or end-stage renal disease patients (creatinine). The proposed breath sensors analyse breath in real-time with on-line display of breath parameters, are portable, simple to operate, inexpensive and offer a sufficiently low limit of detection for the target breath markers, thus making them of high interest for daily clinical practice. Preliminary data in a small study with healthy subjects showed a high correlation between blood glucose levels and acetone.