Introduction
The presence of a bidirectional relationship between oral and systemic health has been well described, highlighting a need to consider oral health in the management of chronic diseases¹. A particularly common chronic disease that affects oral health is diabetes mellitus². In Ireland, there are approximately 190,000 people living with diabetes, 90% of whom have type 2 diabetes; the prevalence in adults aged 50 years and over is 8.5% and is increasing^3,4. In 2016, a set of guidelines was released in Ireland, entitled a “Practical guide to integrated type 2 diabetes care”. These guidelines, which were supported by the Health Service Executive (HSE), aimed to present a model of integrated diabetes care, and were developed in conjunction with the National Clinical Programme Diabetes Working Group⁵. These guidelines did not address the oral health needs of patients with diabetes. However, the interrelationship between diabetes and periodontal disease, and their ability to negatively affect each other, emphasizes the need for guidelines such as the aforementioned, to support and encourage collaboration between medical and dental professionals to ensure optimal co-management of diabetic patients^{2, 6-8}.

Oral health considerations for the diabetic patient
Hyperglycaemia in diabetes is strongly associated with the development of oral complications, including periodontal disease, xerostomia, oral candidiasis and neurosensory disorders such as burning mouth syndrome⁹. Periodontal disease, which is a bacterially induced, chronic inflammatory disorder, which affects the supporting structures of the teeth, including the gingiva (gums) and alveolar bone, is a particularly significant oral complication of diabetes mellitus⁶. It begins as an inflammatory process of the gums and can, if unchecked, progress to involve the supporting structures, including periodontal ligaments and alveolar bone around the teeth eventually leading to tooth loss. The resultant periodontal pocket, that forms around the tooth after loss of supporting structures, presents the ideal environment for the growth of mostly anaerobic microorganisms, and a nidus from which their toxins can spread systemically, while also causing local tissue destruction and alveolar bone loss⁷.

Typical signs and symptoms of periodontal disease include gingival bleeding, gingival erythema, halitosis, tooth mobility, gingival suppuration and resultant tooth loss⁷. The loss of intra-oral hard and soft tissues negatively impacts on masticatory function, thus compromising nutrition as well as affecting both speech and appearance. Tooth loss also increases the functional stress on the remaining dentition, and patients may often require an oral prosthesis, such as a denture, to aid function. Meta-analyses have shown diabetic patients to have an increased susceptibility to the development of periodontal disease ^10-11. In addition to increasing the risk of developing periodontal disease, diabetes can also contribute to the periodontal disease process. Patients with poorly controlled diabetes are three times more likely to develop periodontal disease at the severe end of the spectrum when compared with non-diabetics^12-13.

Importantly, in addition, periodontal disease has been shown to influence diabetic control. Severe active periodontal disease adversely affects blood glucose levels in patients with diabetes. Randomized controlled trials have consistently demonstrated that mechanical periodontal therapy is associated with a reduction in the haemoglobin A1c by 0.4 percentage points at three months, a clinical impact equivalent to adding an additional medication to a patient’s pharmacological regime².

Incorporating oral health into overall diabetic care
The American Diabetes Association’s “Standards of Medical Care in Diabetes” recommends referral of a patient to a dental professional for a comprehensive oral health examination, as part of the initial management of a diabetic patient¹⁴. By contrast, the HSE supported “Practical guide to integrated type 2 diabetes care” does not address the oral health needs of patients with diabetes (other than mentioning dry mouth as a possible new symptom of diabetes) and specifically omits mention of visiting a dental professional as part of overall diabetic care⁵. This Irish guideline supports an integrated model of care for patients with type 2 diabetes, which involves the patient, the General Practitioner (GP), the practice nurse, the diabetologist, the clinical nurse specialist in diabetes, the dietitian, the ophthalmologist and the podiatrist⁵. There is a compelling argument, as outlined in the foregoing, for including dental professionals as part of this integrated model of care^6-8.

The GP and the practice nurse are key to the success of Integrated Care⁵. However, engaging with dental professionals and incorporating oral health as part of overall diabetes care can reduce the morbidity and mortality associated with diabetes-related oral health complications, and may also, by controlling a patient’s periodontal disease, actually improve diabetic control^{2, 6-7}. In addition to the management of oral disease, dental professionals are well positioned to evaluate risk factors and intra-oral signs and/or symptoms indicative of poor metabolic control in patients who have been diagnosed with diabetes, for example xerostomia and oral candidiasis⁶. Dental professionals are experienced in motivating behavioural change in their patients, and these skills may be used to support their medical colleagues to achieve a common goal such as smoking cessation or diet modification, in order to improve the overall health of diabetic patients⁷. Many patients visit their dentist or their dental hygienist more regularly than their medical doctors; thus, providing dental professionals with the opportunity to support their medical colleagues in the detection of undiagnosed diabetes, by facilitating the onward referral of patients who present with poorly controlled periodontal disease or any other signs or symptoms suggestive of hyperglycaemia to their GP for assessment⁷.

There is a significant body of evidence to suggest that diabetes and periodontal disease are interrelated and may negatively affect each another if management is neglected. It is important, therefore, to improve patient awareness of the link between these two diseases, and to advocate for increased collaboration between medical and dental professionals in their co-management^{2, 6}. In 2016, the Centers for Disease Control and Prevention in the United States awarded funding to six state departments of health to support the integration of state chronic disease programs and state oral health programs. With respect to diabetic care, the aim is to develop an enhanced model of care in which oral health and other primary care providers collaborate to deliver integrated, patient-centered diabetes prevention and management.

Opportunities for integrated care
Members of the primary care medical team should inform patients that the risk of periodontal disease is increased by diabetes, and that achieving proper glycaemic control in the presence of active periodontal disease may be more difficult, therefore increasing the risk of diabetic complications^{2, 6}. GPs and/or practice nurses should encourage good oral health practices by asking simple questions such as “Do you have a dentist/dental hygienist?” or “When was your last dental visit?” By bringing the topic of oral health into the GP surgery, members of the primary care medical team can play an important role in the promotion of oral health, the prevention of periodontal disease and the improvement in overall diabetic health⁶. The primary care medical team is in a unique position to ensure that each patient with diabetes has engaged with a dental professional¹³, which in Ireland is accessible privately or through state subsidized schemes such as the Dental Treatment Benefit Scheme or the Dental Treatment Services Scheme. In order to develop these opportunities for integrated care, there would need to be a greater emphasis placed on oral health during GP training, and the training of other members of the primary care team^{2, 15}.

Conclusion
Patients with diabetes are at higher risk of oral health complications, and these complications carry substantial morbidity. In addition, uncontrolled active periodontal disease can worsen glucose control. Based on this, the American Diabetes Association’s guidelines recommend a comprehensive oral health examination by a dental professional as part of diabetes management. In Ireland, this recommendation was not included in the HSE supported guidelines, entitled a “Practical Guide to Integrated Type 2 Diabetes Care”. However, based on the interrelationship between diabetes and oral health, there is a compelling case to be made for routine oral health assessment by a dental professional to be incorporated into Irish guidelines. Simple questioning of the patient about recent dental visits and encouraging engagement with a dental professional as part of their overall disease management is a simple, rapid and effective way of incorporating oral health into comprehensive diabetes care.

Correspondence:
Dr. John Ahern,
Division of Oral and Maxillofacial Surgery, Medicine, Pathology and Radiology,
Dublin Dental University Hospital,
Trinity College,
Lincoln Place,
Dublin 2, D02 F859 Ireland.
E-mail address: [email protected]
Tel: +353 (1) 896 2223

Conflict of Interest
There is no conflict of interest declared from any of the authors named in this article.

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