Inclusion Criteria:  For periodontitis stage III and IV patients according to (Papapanou et al., 2018 and Tonetti et al., 2018)  Bleeding on probing (BOP) ≥ 30%. At least four non-adjacent teeth sites in each jaw having CAL ≥ 5 mm and PD ≥ 6 mm in one or more sites. Tooth loss due to periodontitis ≥ 5 teeth. Presence of a minimum of 15 natural teeth. For diabetes and non-diabetic patients according to ("Diagnosis and Classification of Diabetes Mellitus," 2014) Patients with type 2 diabetes mellitus will be diagnosed as having type 2 diabetes mellitus ≥ 5 years before the study and treated with stable doses of oral hypoglycaemic agents and/or insulin under the supervision of an endocrinologist with their glycated haemoglobin level (HBA1c) > 6%. Non diabetic Patients in the control and stage III and IV periodontitis groups will be selected as having Fasting plasma glucose (FPG) <126 mg/dL.  Exclusion Criteria:  Individuals with any known systemic disease other than type 2 diabetes. Pregnant and lactating women. Individuals that received periodontal treatment within the last 6 months. Individuals with a history of systemic antibiotics and anti-inflammatory drugs within the last 3 months. Former or current smokers.