Clinical Implications and Research Progress of Salivary Biomarkers for Endocrine and Metabolic Disorders

AIMS: Similar to blood, saliva contains a broad range of biomarkers and may offer a non-invasive, repeatable specimen for endocrine and metabolic assessment. This review aims to synthesise and evaluate recent advances in the clinical translation of salivary biomarkers, while providing a critical assessment of the diagnostic reliability and clinical potential of key salivary biomarkers. MATERIALS AND METHODS: PubMed, Web of Science and ScienceDirect were searched for English-language articles published up to July 2025, with emphasis on studies from 2020 to 2025. We included articles with a focus on the clinical translation of salivary biomarkers for endocrine and metabolic disorders. The relevant studies on the physiology underlying the synthesis and transport of salivary biomarkers were also identified. RESULTS: Late-night salivary cortisol is the most clinically established marker and is guideline-endorsed for Cushing's syndrome, while salivary cortisone may improve the diagnostic accuracy. Salivary glycaemic biomarkers, such as glucose, 1,5-anhydroglucitol, fructosamine, glycated albumin and α-amylase, show potential for diabetes screening or monitoring. Salivary uric acid, inflammatory factors and adipokines may reflect hyperuricaemia, obesity and metabolic inflammation. However, most biomarkers remain exploratory and their clinical translation is limited by inconsistent collection procedures, oral disease, medication effects and analytical platforms. CONCLUSIONS: Salivary biomarkers offer a promising non-invasive approach for assessment of endocrine and metabolic disorders. Standardised procedures and large-scale multicentre validation are needed to define reliable clinical cutoffs and perform comparisons with blood-based reference standards. Applications for machine learning and wearable sensing technology can further promote clinical translation.