Periodontal Conditions and Salivary Biomarkers in Type 2 Diabetic Subjects

Objective:  Periodontitis and diabetes mellitus (DM) are chronic diseases sharing co-morbidity and bi-directional relationships. Certain salivary biomarkers have been shown to be up-regulated in periodontitis patients. The current study aimed to investigate salivary biomarkers in subjects with type 2 DM and their associations with periodontal conditions. Method: Seventy-four non-smoking DM subjects with different degrees of glycemic control measured by HbA1c were recruited and received full periodontal examination. There were 32 subjects with no or mild periodontitis and 42 with severe periodontitis, based on the case definition proposed by Tonetti and Claffey (2005). Unstimulated whole saliva was collected and analysed using ELISA assays for levels of interleukin-1β (IL-1β), IL-1 receptor antagonist (IL-1ra) and matrix metalloproteinase-8 (MMP-8). Result: The DM subjects with severe periodontitis showed significantly higher levels of salivary MMP-8 and IL-1β than those with no or mild periodontitis (3357±3026 ng/ml vs. 1150±802 ng/ml, p<0.001; 861±653 pg/ml vs. 546±475 pg/ml, p<0.05, respectively). No significant difference in the levels of IL-1ra was detected between the subjects with and without periodontitis. MMP-8 levels were positively correlated with full-mouth bleeding on probing (FMBOP) (r=0.33, p<0.01), clinical attachment levels (CAL) (r=0.32, p<0.01) and probing depths (PD) (r=0.52, p<0.001).  There were positive correlations between IL-1β levels and FMBOP (r=0.35, p<0.01) and PD (r=0.42, p<0.001). A high correlation was detected between MMP-8 and IL-1β levels (r=0.76, p<0.001). However, there were no significant correlations between the periodontal parameters and the levels of IL-1ra or HbA1c. Conclusion:  This study shows that salivary MMP-8 and IL-1β are significantly associated with severe periodontitis in type 2 DM subjects. Salivary MMP-8 and IL-1β could serve as potential biomarkers for detecting and monitoring type 2 DM patients who are susceptible to periodontitis. Supported by a GRF from Hong Kong Research Grants Council (HKU768411M), and the Modern Dental Laboratory/HKU Endowment Fund to JLJ.