Periodontal disease (gum disease) is very common and can range from gingivitis (reversible inflammation of the gingiva) to periodontitis (inflammation that extends from the gingiva to cause destruction of the surrounding tissues and alveolar bone resorption).⁸ Severe periodontitis, threatening tooth retention, affects approximately 10% of adults; while moderate periodontitis affects 40–60%.⁹ It is worthwhile to note that both conditions are generally painless and therefore can go unnoticed and untreated until the conditions reach an advanced stage. Meta-analyses confirm that reductions in glycated haemoglobin (HbA1c) can follow effective periodontal therapy.^{10 11} Furthermore, in 2010 the Cochrane Collaboration published a review of studies that investigated the relationship between periodontal disease and the glycaemic control of people with diabetes. They reported a reduction in HbA1c of 0.40% 3–4 months after conventional periodontal therapy.¹² The reason for this is still unclear but probably is because of reduced systemic inflammation, for example, reduced serum levels of tumour necrosis factor-α (TNF-α) and interleukin 6 (IL-6). Reduction in HbA1c reduces the risk of diabetic complications. Research carried out by Stratton et al. in 2000 reported that each 1% reduction in HbA1c is associated with 21% reduced risk of any endpoint related to diabetes, 21% for deaths related to diabetes, 14% for myocardial infarction and 37% for microvascular complications.¹³

Education plays a significant role in the management of diabetes. A team of healthcare professionals provide advice to people with diabetes regarding control of their blood glucose, and specialist monitoring of their eyes, feet, heart and kidneys. The addition of dental monitoring could enable people with diabetes to become informed of the potential periodontal complications of their disease. However, the recent Adult Dental Health Survey (2009) stated that 39% of the population do not attend a dentist.⁹ The main reason for dental non-attendance (after ‘having nothing wrong’) is not being able to find an NHS dentist.

Three inter-related themes emerged: (1) uncertain knowledge—a lack of familiarity about the subject area; (2) unworkable knowledge—that even if the links between periodontitis and diabetes were known, it is impossible for anything to be done for patient benefit given the differing systems that medical and dental healthcare professionals work in and (3) isolated knowledge—the perceived division that exists between the medical and dental professions has the potential to negatively impact on advances in diabetes patient care.

Uncertain knowledge: If the interviewees were not already aware of the links between periodontitis and diabetes, this concept was introduced in the study Information Sheet, and the topic was then opened up for discussion during the interview. Three participants (two diabetes nurse specialists and one patient) claimed to have never heard about the links between diabetes and periodontitis prior to reading the Information Sheet (box 1(1)). Generally, the healthcare professionals reported having a minimal knowledge-base on this topic. The links did make sense to the interviewees in the context of what they already knew about the complications of diabetes in general and the effect of infection and inflammation on blood glucose levels. The dental professionals were all familiar with the research linking the diseases. During the course of the interviews, the large body of research that has been carried out in this area, including the recent Cochrane collaboration systematic review, was discussed. Several of the healthcare professionals reacted with surprise to this information, as they had been unaware of the scope of the evidence-base (box 1(2)). There was generally a request for more information on this topic (box 1(3)). Two healthcare professionals did note that they would need more evidence before they would consider the relevance of the research for their own clinical practice (box 1(4)). Patients with diabetes were also poorly informed about the links between diabetes and periodontitis (box 1(5)).

Unworkable knowledge: In broad terms, the interviewees felt that consideration of the oral health status of people with diabetes was a good idea, and they could appreciate the benefits of reduced oral inflammation in terms of having a positive impact on blood glucose levels. However, the absence of any local, regional or national structures to promote or coordinate the assessment and/or management of the oral health of patients with diabetes was felt to be a central source of the problem (box 2(1)). It is not that the impact of oral health on diabetes has never been considered in national guidelines. One of the interviewees had considerable experience in developing and implementing guidelines in diabetes care, and identified that the limited resources for managing diabetes means that there are many priorities competing for inclusion within the guidance given to healthcare professionals (box 2(2)). That interviewee highlighted the potential of commercial funding to raise the profile of oral health within the context of diabetes at the national public policy level which could in turn influence local practice. A common perception among the interviewees was that without the inclusion of oral health assessment into the everyday organisation of diabetes care, for example, through the electronic template that supports the management of their diabetic patients, then research into the impact of periodontitis and its treatment on glycaemic control is never likely to have an impact on patient care. They indicated the potential of the template to ‘shape’ aspects of patient management (box 2(3)) especially in relation to diabetic nurse specialists, who were often positioned as actively employing more protocol-driven care (box 2(4)).

Isolated knowledge: Healthcare professionals alluded to a feeling of isolation when dealing with the oral problems of their patients. A common theme from the medically qualified interviewees was that they felt there is little education in dental subjects at the undergraduate (medical student) level and this seemed to impact on their considerations about the systemic impact of oral diseases. It was accepted that the medical curriculum was unable to cover everything and that the mouth is generally considered by medics as being the ‘realm of dentists’. However, their training failed to prepare them for managing the dental complaints that they faced during their clinical practice. The problems that can arise as a result of their limited knowledge of dentistry were highlighted by the GPs who reported the frequent occurrence of patients coming to visit them when they had an oral or dental problem. The existence of a separate profession who specialise in dentistry will not prevent the public from going to their doctor if they have a problem with their mouth (rather than going to a dentist); and doctors recognised, albeit reluctantly at times, the need to provide at least some limited care (box 3(1)). This reluctance was tangible and the issue of a division between the medical and dental professions arose repeatedly (box 3(2)). GPs felt a strong sense of isolation when put in the position of trying to manage patients with dental problems. One interviewee stated that he felt ‘…untrained and unsupported…’ (HCP02, GP with a specialist interest in diabetes) in this area. GPs do not like having to see patients with ‘jaw ache’ who cannot, for whatever reason, see their dentist. GPs also seemed to question the contribution of dentists to the care of all patients at all times, with a perception that dental practices were run as small businesses, somewhat outside the NHS (box 3(3)). In turn, dentists were also aware of a ‘divide’ between themselves and their medical colleagues, and perceived the negativity that they detected as doctors asserting their superiority (box 3(4)). The patients indicated that they felt their GPs had a pivotal role in informing them about all the possible complications of diabetes and that better collaboration between medical and dental healthcare providers could only be of benefit (box 3(5)).

Healthcare professionals’ knowledge about the links between diabetes and periodontitis was found to be relatively minimal in this study population. Further research is necessary to identify how these findings apply more broadly; for example, a questionnaire survey could target healthcare professionals across a range of disciplines and at various geographical locations. Although the benefits of screening for, and treating, periodontitis in patients with diabetes were recognised, a number of barriers were identified that would need to be addressed before patients would benefit from the evidence-base. Clearly, awareness of the current evidence-base could be raised in a range of settings, including undergraduate, postgraduate and continuing medical education. As clinical routines are based on a mixture of education, evidence, experience and habit, improving the awareness of healthcare professionals of the bidirectional relationship between periodontitis and diabetes alone,⁷ will not necessarily translate to patient benefit. The inclusion of the oral complications of diabetes into local care pathways, electronic templates and national diabetes guidelines could also help. However, protocols and guidelines, although an excellent way to implement new clinical interventions, are not the only way to influence the practice of healthcare professionals.¹⁹ The role of key opinion leaders, commercially supported local networking events and peer-led discussion forums such as lunchtime practice seminars, were also highlighted by the interviewees as being potentially effective ways to raise general awareness of the links between periodontitis and diabetes, and the current evidence-base such as the Cochrane review.

Any implementation of change needs to be situated with the context of both public and professional cultures in relation to oral health. The last Adult Dental Health Survey (2009) stated that the most frequent reasons for dental non-attendance are that patients cannot find an NHS dentist (or their dentist has just changed from providing NHS care to private care only), they cannot afford to go, or they are afraid to go to the dentist.⁹ In the UK, the relationship between a patient and their dentist is different from the relationship with their doctor, because even when receiving NHS dental treatment, there is a financial element involved with virtually every appointment (unless the patient is in receipt of certain benefits).²⁰ As yet, we have relatively little knowledge of how people with diabetes seek oral healthcare and how this could impact on promoting oral health screening. In this research, we have also documented some of the divisions that exist between the medical and dental professions, specifically related to the links between periodontitis and diabetes. These divisions are not new; they have existed since the medical and dental professions first emerged as independently regulated professions which, in the case of Britain, was in the early to mid-20th century.^{21 22} From the outset, the distinction was made that dental health was the jurisdiction of dentists and quite separate, although closely related, to general health. This state of affairs has existed with little dispute from either professions for many years. Clearly, this tension has the potential to impact on any intervention introduced to promote interprofessional collaboration.

As the prevalence of diabetes is growing, so is the cost of treating it. During 2010/2011, the direct cost to the NHS for treating diabetes was £9.8 billion (the indirect cost being £13.9 billion).²³ In total, 80% of the direct costs were reported to go towards treating the complications of the disease, many of which are preventable. Diabetes UK reports that the economic burden to the NHS, for both direct and indirect costs of diabetes is estimated to rise to £16.8 billion by 2035/2036, which equates to a predicted 17% of the total health resource expenditure for the NHS.²³ Diabetes is a major risk factor for periodontitis⁴ and periodontitis appears to impair glycaemic control in people with diabetes.²⁴ Furthermore, periodontal treatment results in improvements in glycaemic control, which although modest (HbA1c reductions of approximately 0.4%), could be clinically relevant, and are similar to reductions achieved by some oral therapies such as the gliptins. Interprofessional collaboration in the form of education and practice may enhance the management of chronic diseases, such as diabetes, through the management of their common risk factors, underlying social determinants and their common biological pathways.²⁵ Interprofessional collaboration already exists for management of certain complications of diabetes, such as the established screening programmes to assess for retinopathy.

Clearly, the value placed on screening programmes will be linked to the morbidity associated with the complication that is being assessed. Given that patients and most healthcare providers in our sample appeared to be relatively uninformed about the links between diabetes and periodontitis, assessing oral health may be regarded as having a lower priority than assessing retinal health, for example. On the other hand, periodontitis has a major impact on quality of life,¹⁸ and the early loss of teeth can be a very distressing outcome for any patient. Therefore, diabetes care teams could inform patients with diabetes about their increased risk for periodontitis, and of the importance of obtaining dental care, as proposed in the suggested brief oral health intervention (in box 4). The validity of such an approach would need to be tested in future research. It may also be worthwhile investigating the use of leaflets or posters to provide more information for patients, and ultimately, the inclusion of a dental hygienist into diabetes care teams to undertake oral health assessments could benefit patients and enhance interprofessional working.