There is now overwhelming scientific evidence that diabetes mellitus and periodontal disease have a biological link1 and a two-way relationship,2 although the mechanism remains unclear. People with diabetes have a 3-4 times greater risk of developing periodontal disease than people who don't, rising to ten times for smokers.3

Dentists have been taught about these links, first described in 1928,4 but doctors have not; not least in the UK, as a question about dental status has been omitted from the National Institute for Health and Care Excellence (NICE) annual diabetic systems checks and the Department of Health and Social Security's own website until June 2022. It is clear that treatment for periodontal disease improves glycaemic control,5 may lead to a reduction in diabetic medications and reduces the severity of the known medical complications.5

While this should be helpful for those people with diabetes who do access dental care, there is at least half of the UK population who do not. How are they going to find out about a possible health benefit of dental care?

It follows that there is a need to inform doctors and for they and dentists to work together.6,7Doctors cannot do it themselves because they do not know. That educational lead should come from dentists as follows:

  • For those people with diabetes who do have dental care, send a copy of the Basic Periodontal Examination scores with an explanation about what they mean either directly to your patient's general practitioner (GP) or via the patient themselves.7 The highest overall score from the sextants is the risk factor. Ask in return for the HbA1c glycated haemoglobin scores. These two scores have been classified using a traffic light (red, amber and green) system to simplify identifying the level of risk (Appendix 1)

  • Dental postgraduate tutors should contact their medical counterparts and find a lecturer who can talk to doctors about this important omission in their professional training and knowledge

  • Deans of dental schools should contact the deans of medical schools about adding this to the curriculum and find a lecturer who can talk to medical students about this important omission in their professional training and knowledge

  • NICE have been asked to add dental questions8 as the sixth complication9 to doctors' annual diabetic health checks for five other conditions. Now, doctors should advise their patients living with diabetes that they are at greater risk of developing periodontitis and that periodontal treatment may improve glycaemic control. However, dentists have not been informed of this change in medical practice.

There is a compelling argument for a paradigm shift in the care of people with diabetes for both doctors and dentists and a need to identify those patients who are at greatest risk. This should be straightforward for patients attending for dental care if the proposed pro forma (Appendix 1) is trialled.

For those patients that doctors identify in the highest-risk groups that are not receiving dental care, where should they be referred for a dental screening and opinion when dentists have either left, or are planning to leave, the NHS and there is already insufficient capacity to cope? In the short term, this could include referrals for hospital consultants to dental departments, or for GPs, a referral to an expanded community dental service. A more radical solution to free up professional time could be to limit NHS dental checks to yearly rather than six-monthly. In the medium to long term, more dentists and hygienists should be recruited and trained. With these limitations, it follows that identification of people with diabetes in the highest-risk categories should have priority.

A secondary and equally important issue concerns the Basic Periodontal Examination scores and whether or not the existing categories are sufficiently robust as predictors of the above periodontal risks. Since its introduction nearly 40 years ago, the community periodontal index of treatment needs (CPITN) has become a worldwide standard method of screening for periodontal disease.10

As it stands, the score of 2 for calculus covers both supra- and sub-gingival types. Using the above classification, a patient with diabetes with minimal levels of supra-gingival calculus and otherwise excellent levels of plaque control, no bleeding on probing, or pockets greater than 3 mm, would score 2 and be placed in the amber, medium-risk group; an incorrect assessment of their real risk level.11

There is general agreement that sub-gingival calculus is more deleterious than supra-gingival calculus. With this in mind, the time has come to re-evaluate the score of 2.

In the early development of the CPITN system, it was recognised that the score of 4 for pockets greater than 5.5 mm depth was too imprecise and 4* was created for pockets greater than 8.5 mm. A similar argument about imprecision can be made for the score of 2. By adding a star to this group, making 2 = supra-gingival calculus and 2* = sub-gingival calculus, it may be possible to improve the prognostic value of these scores, with 0, 1 and 2 as green (low risk) and 2* and 3 as amber (the medium-risk category).

The World Health Organisation is invited to make these changes to the score of 2.

I am reminded of James Lind's 1770 dictum to the Board of Admiralty about the benefits of fresh fruit to combat scurvy aboard warships that took 40 years to be implemented. I suggest that the dental profession should commit to implementing the changes I have proposed by 2028, the centenary of Williams' paper, 'Diabetic periodontoclasia'.4

To quote James Lind, 'the province has been mine to deliver precepts: the power of execution lies with others'.

figure 1

Appendix 1 Proposed pro forma