Periodontitis is a chronic disease of the supporting tissue of the teeth, characterized by bleeding and inflamed gingival, resorption of alveolar bone. This disease has a significant impact of the quality of life as the teeth become progressively mobile and may fall out spontaneously if no treatment is provided. Periodontal disease has been cited as the sixth complication of diabetes mellitus.Chromogranins / secretogranins are a family of proteins present in nervous endocrine and immune cells, released with catecholamines during stress situations. Chromogranin A (CGA) is the major member of this family.The aim of this study is to determine the level of CGA and its derived peptides in the gingival crevicular fluid (GCF) of health or diabetic patients with and without periodontitis.Then, we want to determine the antimicrobial activity of these peptides.