CRP and diabetes mellitus: Periodontitis affects periodontal supporting tissues, consisting of gums, periodontal ligaments, cementum, and alveolar bone (1). Moreover, periodontitis is quite connected with increased systemic inflammatory factors, such as C-reactive protein (CRP), interleukin-6 (IL-6), interleukin-8 (IL-8), fibrinogen and white blood cells. Periodontitis can increase the inflammatory burden of the body, leading to the deterioration of some systemic diseases, such as cardiovascular disease (CVD) (2), diabetes (3), digestive tract cancers (4) and so on.