Salivary cytokine signatures and their association with glycaemic markers in adults with type 2 diabetes

Objective: To investigate salivary pro- and anti-inflammatory cytokine profiles in adults with type 2 diabetes (T2D) and their associations with glycaemic markers. Material and Methods: A cross-sectional study was conducted including 20 adults with T2D and 20 age-matched controls. Unstimulated saliva was collected, and concentrations of IL-1β, IL-4, IL-6, IL-8, IL-10, IL-17A, IL-22, TGF-α, and TNF-α were quantified using a multiplex immunoassay. Fasting blood glucose (FBG) and glycated haemoglobin (HbA1c) were obtained from clinical records. Results: T2D group exhibited higher salivary IL-6 and IL-10 levels compared with controls. Several pro-/anti-inflammatory cytokine ratios, including IL-1β/IL-10, IL-8/IL-10, TGF-α/IL-10, and TNF-α/IL-10, were significantly altered in the T2D group. In the T2D group, IL-1β, IL-6, IL-10, IL-22, TGF-α, and TNF-α were positively correlated with FBG, whereas specific ratios, such as IL-22/IL-4 and TNF-α/IL-4, were positively associated with HbA1c. Conclusion: Adults with T2D display a distinct salivary cytokine profile characterised by elevated IL-6 and IL-10 and altered pro-/anti-inflammatory ratios. Salivary cytokine levels are associated with both short- and long-term glycaemic control, suggesting that salivary biomarkers can reflect systemic metabolic and inflammatory status.