Scientists have developed a mouth guard to test health markers, such as lactate, cortisol and uric acid, in saliva.
The mouth guard can then transmit the information wirelessly to a smart phone, laptop or tablet.
According to engineers at the University of California, San Diego, the technology, which is at a proof-of-concept stage, could be used to monitor patients continuously without invasive procedures.
The technology could also be used to monitor athletes' performance or stress levels in soldiers and pilots.
The study focused on uric acid, which is a marker associated with diabetes and gout,
Gout is a disease in which defective metabolism of uric acid causes arthritis.
At present, the only method to monitor the levels of uric acid in a patient is to draw blood.
The research team describes the mouth guard's design and performance this month in the journal Biosensors and Bioelectronics.
"The ability to monitor continuously and non-invasively saliva biomarkers holds considerable promise for many biomedical and fitness applications," said nano engineering professor Joseph Wang at the University of California.