TNF and periodontitis: For instance, a genetic link between periodontics and GDM may exist [52], as some studies have postulated a possible existence of genetic polymorphism between inflammatory cytokines such as tumor necrosis factor alpha, interleukin-1 and interleukin-6, insulin resistance and periodontitis [53, 54] such that their derangement may concurrently cause periodontitis and GDM.