Diabetes and periodontitis: the relationship runs in both directions

The link between diabetes and periodontitis is among the best documented of the oral-systemic connections, and it is bidirectional: each condition worsens the other.

Uncontrolled diabetes increases susceptibility to periodontitis through several mechanisms. Hyperglycaemia impairs neutrophil function, reduces repair capacity and promotes advanced glycation end products in the tissues.

These render collagen less elastic and harder to remodel, which explains why healing after periodontal therapy is slower in a diabetic patient.

The opposite direction is the less familiar and clinically more interesting one. Extensive periodontitis constitutes a systemic inflammatory burden that contributes to insulin resistance.

Reviews indicate that periodontal treatment in diabetic patients produces a reduction in glycated haemoglobin, modest in extent but clinically relevant and comparable to adding a medication.

It is a finding worth communicating to the patient and, where possible, to their diabetologist, because it moves periodontal therapy from local intervention to a component of metabolic management.

Glycated haemoglobin is the parameter to ask for in the history, and the value should be requested, not whether the diabetes is controlled. Patients' perception of their own control tends to be optimistic.

Values below seven per cent indicate good control and a periodontal risk close to that of the general population. Above eight per cent the risk rises appreciably and treatment response worsens.

Above nine per cent elective surgical procedures should be deferred, and the priority becomes metabolic control in agreement with the physician.

Recall frequency should be increased relative to non-diabetic patients. Intervals of three or four months are the prevailing recommendation, against six for the general population.

Xerostomia is common in diabetes, both from the disease and from medication, and adds a root caries risk to be addressed with high-concentration fluoride.

Oral candidosis is more common and should be actively sought, particularly in denture wearers, where it combines with denture stomatitis.

In summary: the relationship is bidirectional and periodontal treatment bears on glycaemic control, the glycated haemoglobin value is requested rather than an impression, above nine per cent elective surgery is deferred, and recalls move to three or four months.