Aim: The study aims to investigate the presence of a specific gene, cytotoxic associated gene-A, as a potential salivary biomarker in individuals with periodontitis. Materials and Methods: 45 salivary samples (15 from healthy patients and 15 from periodontitis patients with diabetes mellitus, 15 from periodontitis patients without diabetes mellitus) are appropriately collected, labelled, and stored. Pre-coated anti-human cytotoxic associated gene-A antibody is used to detect biotinylated polyclonal antibodies. The measurement of the colour intensity, which is positively correlated with the quantity of the target in the sample. Results and discussion: The mean concentration of Cytokine associated gene-A in saliva was increased consistently as the disease progressed from healthy state to periodontitis. It was highest in group 2 and lowest in group 1. Mean concentration of Cytokine associated gene-A in group 1 was 118.42ng/ml, 584.32ng/ml in group 2 and 465.72ng/ml in group 3 respectively. The results state the presence of cytotoxic associated gene-A salivary biomarker in elevated levels in the salivary samples of the periodontitis patients when compared with samples of the healthy patients. Conclusion: The cytotoxin associated gene-A salivary biomarker level is elevated in the periodontitis patients with diabetes mellitus and it can be used for the prior detection of periodontitis.