Non-invasive glucose determination in both human and canine saliva with a paper-based microfluidic device

Monitoring glucose levels is the most common method for managing diabetes, a chronic metabolic disorder characterized by elevated blood glucose that can lead to severe complications. According to the International Diabetes Federation (IDF), in 2021, 10% of adults were living with diabetes, a figure projected to rise to 12.5% (1 in 8) by 2045 [1]. With the aging global population, elderly individuals face daily challenges in glucose monitoring. While current devices primarily rely on invasive blood sampling and electronic sensors, including implanted systems, these technologies can be difficult for older users. Diabetes also significantly affects companion animals, particularly dogs and cats. The disease is estimated to affect about 0.3-1.3% of dogs in countries including the UK, USA, Sweden, and Italy, with prevalence increasing sharply over recent years [2]. To address accessibility and ease of use, we propose a simple, accurate, and user-friendly paper-based microfluidic device for glucose quantification in saliva (Fig.1), eliminating the need for electronic readers. Microfluidic paper-based devices (pPADs) are increasingly recognized as promising point-of-care tools due to their low cost, rapid response, and ease of use. Importantly, the developed pPAD enables non-invasive glucose monitoring in both human and canine saliva, broadening its application to veterinary medicine as well as human healthcare. This dual-use approach highlights the potential of saliva as an alternative diagnostic fluid and offers a practical alternative to conventional blood-based invasive methods.