oral health education should be provided to all patients with diabetes. Patients with diabetes should be informed that periodontitis risk is increased, and if untreated, that periodontitis has a negative impact on metabolic control and may also increase the risk of complications of their diabetes such as cardiovascular and kidney disease. Therefore, successful periodontal therapy may have a positive impact upon their metabolic control and can prevent diabetes complications.
Physicians should investigate a prior diagnosis of periodontitis. For all patients, disease testing should begin at the age of 45 years. If results are within the normal range, the test should be repeated at 3-year intervals, but in those with pre-diabetes, the re-test and risk status should be assessed annually. In case of a positive diagnosis, the physician should ascertain whether periodontal care and maintenance are being provided. If patients are symptomatic (polydipsia, polyuria, polyphagia, unexplained weight loss), they should be referred directly to a physician. Nasseh et al222 found a statistically significant association between periodontal intervention and lower health care costs. However, this association was only noted among individuals who did not initiate diabetes drug therapy after diagnosis. For instance, individuals newly diagnosed with T2DM, who had undergone periodontal intervention, had total health care costs that were $1799 lower on average over years 3 and 4 compared with those who did not have periodontal therapy. These data suggest not only a positive effect of periodontal therapy on the course of DM, but also on the economic burden imposed by DM.
The American Diabetes Association suggests that periodontal screening should be considered in overweight or obese adults who have one or more of the following risk factors223:
● HbA1c ≥ 5.7%, impaired glucose tolerance, impaired fasting glucose on previous testing
● first-degree relative with diabetes
● high-risk race/ethnicity (e.g. African American, Latino, Native American, Asian American, Pacific Islander)
● women who were diagnosed with gestational DM
● history of cardiovascular disease
● hypertension (≥ 140/90 mmHg or on therapy for hypertension)
● HDL cholesterol level < 35 mg/dl and/or a triglyceride level > 250 mg/dl
● women with polycystic ovary syndrome
● physical inactivity
● other clinical conditions associated with insulin resistance (e.g. severe obesity, acanthosis nigricans).
The interplay between periodontitis and DM has been extensively studied for over 70 years, and with evidence from epidemiological studies and clinical trials, complex interactions between these two distinct pathologies have been demonstrated. Diabetic patients with uncontrolled serum glucose levels are more likely to suffer from periodontitis, compared with well-controlled diabetics and healthy people. At the same time, periodontitis also bears upon the effectiveness of diabetes control. However, improvement of clinical periodontal parameters following standard non-surgical therapy together with effective oral hygiene can be achieved even in people with poorly controlled diabetes. There is also consistent evidence that severe periodontitis affects HbA1c in individuals with and without diabetes. Taken together, moderate to severe periodontitis is associated with an increased risk for the development of diabetes and the existing evidence supports a dose-dependent role for periodontitis and diabetes complications.
Alongside the clinical evidence for this association, studies ventured to understand the biological mechanism that links periodontal condition and diabetes. The effect of T2DM on the inflammatory status of the periodontal tissues is well established. Studies show clearly that hyperglycaemic conditions augment the pro-inflammatory response in the periodontal environment, such as increase of TNF-α, CRP and mediators of oxidative stress. Diabetes affects many biological properties, including cell functions, pro-inflammatory cytokines and alterations in the RANKL/OPG ratio, mediated by hyperglycaemia and AGEs, which accumulate in the periodontal tissues. Weak evidence shows the effect of diabetes on the periodontal microbial composition. Some studies show that periodontal therapy lowers the levels of circulating inflammatory mediators and that this can lead to improved glucose homeostasis. It is important to highlight that some of the published data investigating the mechanistic background linking periodontitis and obesity or DM are very controversial. As a consequence, more human studies are needed to explore the aspect of the bidirectional relationship between periodontal diseases and diabetes, which can contribute to the understanding of the biological mechanisms and the better way to approach these patients in terms of health care. In addition, more animal studies are needed to explore the biological effect of periodontitis on diabetes.
Diabetes requires complex medical care and patients should be asked by physicians whether or not they have seen a dental practitioner in the past year. In addition, physicians should recommend that patients with diabetes have a thorough periodontal evaluation by a dental professional. Finally, the oral health care team has a role to play in identifying both pre-diabetes and undiagnosed DM, and in turn physicians need to be aware of periodontal diseases and their implications in people with diabetes.
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