Our clinical protocol, “Daytime circadian patterns of exhaled volatile organic compounds in adults without and with type 1 and type 2 diabetes,” has been published in BMJ Open. The study investigates how circadian rhythms influence exhaled volatile organic compound (VOC) profiles and whether these patterns differ between individuals with and without diabetes. It addresses a key limitation in current breath analysis studies, namely the lack of standardized sampling across time of day. In this prospective observational study, 60 participants will undergo repeated breath measurements between 08:00 and 16:00 using GC-IMS, alongside glucose measurements, body composition analysis, questionnaires, and microbiota sampling. The primary objective is to characterize temporal variation in VOC signals, with secondary analyses focusing on group differences and associations with metabolic parameters. This work establishes the methodological basis for studying dynamic metabolic signatures in breath and supports the development of time-resolved, non-invasive sensing approaches in diabetes.
