Salivary Pi Levels Exhibit a Significant Positive Correlation With Salivary Glucose Concentrations

Objectives: Saliva of individuals with type 2 diabetes mellitus (T2D) exhibit reduced salivary flow, lower pH, and enriched urea levels when compared to normoglycemic controls. However, findings regarding salivary levels of calcium (Ca) and inorganic phosphate (Pi) remain inconclusive. The inorganic content of saliva constitutes a crucial aspect of oral equilibrium. This study aimed to characterize the composition of saliva in T2D and non-T2D individuals, with a specific focus on Ca and Pi, and investigate their potential correlations with glycemic levels and other clinical parameters.
Methods: A cross-sectional study was conducted including dentate adults (>35years-old). Sociodemographic, anthropometric, food frequency consumption, and clinical parameters were collected by calibrated examiners. Blood and saliva samples (rest and stimulated) were obtained on the same day to assess glycemic levels. Salivary Ca and Pi concentrations were quantified using spectrophotometry from the stimulated saliva. Statistical analyses were performed comparing averages between groups, as well as using Pearson/Spearman's correlation and Linear regression models (p<0.05 significance level).
Results: The sample comprised 101 individuals (51±13 years-old), from which 72 had a diagnosis of T2D. The mean rates of salivary Ca, Pi, and glucose concentrations were 4.9±2.43mg/dL, 6.6±1.1mg/dL, 39.01±29.05 for individuals with T2D, and 5.3±2.44mg/dL, 6.5±1.2mg/dL, 34.01±12.9mg/dL for those without T2D, respectively (p>0.05). A significant weak correlation between the Ca salivary levels and stimulated salivary flow was observed (p=0.02). Salivary Pi was positively correlated with salivary glucose levels (p=0.017), and negatively correlated with the number of teeth (p=0.016), and dietary fiber consumption (p=0.016). Yet, none of the variables were significant in the linear regression models.
Conclusions: Changes in the inorganic composition of the hyperglycemic saliva, such as Pi levels, could potentially compromise its protective mechanisms leading to higher risk of ionic imbalance.