Salivary Metallothionein Level in Type 2 Diabetes Mellitus Patients with and without Chronic Periodontitis: A Cross-sectional Study

Introduction: Metallothionein (MT) is a cysteine-rich protein involved in cellular defence mechanisms, including the regulation of oxidative stress and immune responses. Oxidative stress is a common link between Diabetes Mellitus (DM) and periodontitis, two chronic inflammatory conditions with a bidirectional relationship. Although MT has been widely studied in diabetes, its role in periodontal disease and the combined impact of both conditions on MT expression remain unclear. Aim: To evaluate the levels of MT in the saliva of diabetic patients with and without periodontitis. Materials and Methods: The present cross-sectional study was conducted at Sri Ramachandra Dental College and Hospital, Chennai, Tamil Nadu India, over two months (February to March 2021), involving 76 participants divided equally into four groups (n=19): healthy controls, Chronic Periodontitis (CP), Type 2 Diabetes Mellitus (T2DM), and T2DM with periodontitis (T2DM+CP). Clinical periodontal parameters-gingival bleeding index, Plaque Index (PI), Probing Pocket Depth (PPD), Clinical Attachment Level (CAL), and Periodontal Inflamed Surface Area (PISA)-were recorded. Salivary metallothionein levels were measured using EnzymeLinked Immunosorbent Assay (ELISA). Data were analysed using Statistical Package for Social Sciences (SPSS) software with the Shapiro-Wilk test, one-way Analysis of Variance, Dunn’s post-hoc test, and Spearman’s correlation (p<0.05). Results: The T2DM+CP group showed significantly higher periodontal parameters and glycaemic levels compared to the other groups (p<0.05). Salivary MT levels were also highest in this group and were statistically significant, with a p-value of <0.05 when compared to the other groups. A positive correlation was observed between MT and glycaemic levels, and a moderately positive correlation (r-value of 0.507) was noted between MT levels in patients with T2DM and periodontitis. Conclusion: Elevated salivary MT levels in diabetic patients with periodontitis suggest a potential role as a biomarker of oxidative stress and disease activity. Further longitudinal and interventional studies are needed to validate MT as a diagnostic and prognostic marker.