More research is emerging that suggests a bidirectional relationship between both types of diabetes and periodontal disease: the body responds to severe periodontitis with an increased blood glucose level, while periodontitis makes it more difficult for the diabetic to control their blood glucose level.50,51 It is accepted that the removal of periodontal pathogens can slow or arrest the progression of periodontitis by reducing local inflammation. However, the diabetic patient, being at a greater risk of developing periodontitis due to impaired immune responses, may not respond as well to periodontal therapy as a non-diabetic patient. An hypothesis on the basis of a direct inflammation theory in linking oral disease to systemic health is that serum levels of inflammatory mediators that cause insulin resistance may be reduced through periodontal therapies, which may improve glycaemic control.
A conclusive meta-analysis by Janket et al. revealed that periodontal treatment does not affect glycaemic control by reducing A1C levels in diabetic patients, but recognized that the study designs impacted on the results. The variety of periodontal treatments (non-surgical with and without antibiotics) and unbalanced population samples (type 1, type 2 or mixed) lend to conflicting results, and it was therefore strongly recommended that further studies, possibly restricted to type 2 diabetics not on insulin regimens, could more accurately demonstrate the significant effects of periodontal therapies on glycaemic controls in diabetics.51
Further rigorous and controlled studies of the treatment of periodontal disease in diabetics are needed to confirm the extent to which treatment enhances glycaemic control. However, there is evidence that well-controlled diabetics respond to periodontal therapies similarly as non-diabetics and diabetics continually challenged may have a less favorable outcome over the long term.50-52