Monitoring rapid metabolic changes in health and type-1 diabetes with breath acetone sensors

Routine detection of health parameters is desirable to recognize the early onset of metabolic diseases (e.g., diabetes mellitus) and to personalize their treatment. Promising are non-invasive, affordable and portable technologies, such as breath sensors. Yet, the selective monitoring of breath markers (e.g., acetone for lipolysis) with sensors to track metabolic changes that can reveal disease-related abnormalities remains challenging. Here, subtle breath acetone changes during fasting, exercise and glucose ingestion are tracked in two model situations: Patients suffering from type-1 diabetes mellitus (T1DM) and healthy subjects (total: 19 volunteers) were monitored using chemoresistive sensors based on Si/WO3 nanoparticles. Specifically, each subject cycled after overnight fasting to stimulate fatty acid oxidation followed by an oral glucose tolerance test (OGTT), as moni-tored by capillary blood glucose and beta-hydroxybutyrate (BOHB) concentrations. The sensor recognized accu-rately the individual breath acetone patterns before and after OGTT (both R2 = 0.9) at negligible interference, for instance, from glucose ingestion-associated volatiles (e.g., ethanol) or isoprene, as confirmed by high-resolution mass spectrometry. Furthermore, distinct differences in the breath acetone patterns of T1DM over healthy subjects were revealed including higher (t-test, p = 0.006) breath acetone ratio 2 h after starting the OGTT. Worth noting is that after glucose intake, breath isoprene steadily increased for T1DM subjects while it remained rather constant for healthy ones, an intriguing observation that requires more research to clarify its biochemical origin and medical relevance.