Local inflammatory reactions in patients with diabetes and periodontitis

The impact of diabetes mellitus on the prevalence, severity and progression of periodontal disease has been known for many years and intense efforts have been made to elucidate the underlying mechanisms. It is widely reported that hyperglycemia causes numerous systemic changes, including altered innate immune-cell function and metabolic changes. The aim of this review was to summarize and discuss the evidence for mechanisms that probably play a role in the altered local inflammatory reactions in the periodontium of patients with diabetes, focusing on local changes in cytokine levels, matrix metalloproteinases, reactive oxygen species, advanced glycation end-products, immune-cell functions, the RANKL/osteoprotegerin axis and toll-like receptors. Apart from the systemic effects of diabetes, recent evidence suggests that local changes in the periodontal tissues are characterized by enhanced interactions between leukocytes and endothelial cells and by altered leukocyte functions [resulting in increased levels of reactive oxygen species and of proinflammatory cytokines (interleukin-1β, interleukin-6 and tumor necrosis factor-α)]. These local changes are amplified by the enhanced accumulation of advanced glycation end-products and their interaction with receptors for advanced glycation end-products. Furthermore, the increased levels of proinflammatory cytokines lead to an up-regulation of RANKL in periodontal tissues, stimulating further periodontal tissue breakdown.