Continuous Monitoring of Breath Acetone, Blood Glucose and Blood Ketone in 20 Type 1 Diabetic Outpatients Over 30 Days

Breath analysis has received continuously increasing attention because of its potential as a non-invasive method for disease diagnosis and metabolic status monitoring. Among thousands of breath volatile organic compounds (VOCs), acetone is the second to the highest abundant species in normal human breath gases, which has been extensively studied as a breath biomarker of diabetes or as a high abundant breath VOC in various physiological cases since 1950s [1,2]. To date there are more than 50 independent studies of breath acetone (BA) using various techniques and methods in a laboratory or in a clinic [3-5]; more than 3211 human subjects including 626 diabetic patients have participated in these studies. However, one issue in breath acetone measurements, which is often neglected, is that many intra-individual biological parameters (age, gender, body mass index (BMI), etc.) influence the BA concentration [6-9]. Therefore, it would be insightful to study longitudinal variations of BA in given individuals that have no baseline effect resulting from individual physiological heterogeneity. Diskin et al. monitored five metabolites including acetone in the breath of five healthy volunteers over a 30-day period (excluding weekend days) [10]. The results show that the distribution patterns for these various metabolites for a given individual are apparently like a crude fingerprint, which could act as a baseline for the future to reveal the onset of adverse clinical conditions once it established. Subsequently, Turner et al. determined concentrations of three common breath metabolites: ammonia, acetone, and propanol in the exhaled breath of 30 healthy volunteers over a 6-month period (collection of samples at weekly intervals) [11]. The results show that there is a wide range of concentrations of the three breath metabolites and that abnormally high concentration of these metabolites can be indicative of a particular state of a disease. The two results mentioned above shows the promising of breath acetone used for the management of adverse clinical conditions for a given individual. For given individuals, diurnal variations including fasting, exercise, and diet were also reported to correlate to BA concentration [12-20]. Therefore, a systematic study of the longitudinal variation of BA for given individuals under a control condition is a rationally sound methodology to illustrate a more accurate picture of breath acetone and its possible relations to other clinical parameters such as blood glucose (BG) and blood ketone (BK).