Levels of Neuregulin-4 and Its Receptor ErbB4 in Periodontitis Patients With and Without Diabetes Type 2

Inclusion Criteria: * For periodontitis stage III and IV patients according to (Papapanou et al., 2018 and Tonetti et al., 2018) 1. Bleeding on probing (BOP) ≥ 30%. 2. At least four non-adjacent teeth sites in each jaw having CAL ≥ 5 mm and PD ≥ 6 mm in one or more sites. 3. Tooth loss due to periodontitis ≥ 5 teeth. 4. Presence of a minimum of 15 natural teeth. For diabetes and non-diabetic patients according to ("Diagnosis and Classification of Diabetes Mellitus," 2014) 5. 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%. 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: 1. Individuals with any known systemic disease other than type 2 diabetes. 2. Pregnant and lactating women. 3. Individuals that received periodontal treatment within the last 6 months. 4. Individuals with a history of systemic antibiotics and anti-inflammatory drugs within the last 3 months. 5. Former or current smokers.