This study will evaluate whether HbA1c screening can be performed in dental care to detect elevated blood glucose in patients with advanced periodontitis and support referral to primary care.

Periodontitis is a common chronic inflammatory disease affecting the supporting tissues of the teeth. Advanced periodontitis is associated with prediabetes, type 2 diabetes and cardiovascular disease. The relationship between periodontitis and diabetes is bidirectional: diabetes increases the risk and severity of periodontitis, while periodontal inflammation may contribute to impaired glucose regulation. Patients with advanced periodontitis may therefore represent a group at increased risk of undetected elevated blood glucose. Many of these patients visit dental care regularly but may not otherwise be reached by structured medical prevention.

This is a cross-sectional observational feasibility study conducted in public dental clinics in Skåne, Sweden, in collaboration with primary care. Adult patients aged 18 years or older with advanced periodontitis, defined as periodontitis stage 3-4 or grade B/C, will be invited to participate during a routine dental visit. Patients with previously diagnosed diabetes will not be included.

After informed consent, participants will complete or update a health declaration and undergo capillary HbA1c testing at the dental clinic using a validated point-of-care instrument. Participants will receive their test result. Those with HbA1c ≥42 mmol/mol will receive standardized information and be referred to their listed primary care centre for further diagnostic assessment and preventive follow-up according to routine clinical practice.

The study will assess how feasible this pathway is in routine dental care. Outcomes include participation rate, successful HbA1c testing, time required for study procedures, prevalence of elevated HbA1c, proportion referred to primary care, completed primary care follow-up within six months, dropout and costs. Follow-up data will be collected from medical records and regional registers.

The study may provide a practical model for collaboration between dental care and primary care, with the long-term aim of improving early detection of prediabetes and diabetes and strengthening preventive care for patients with advanced periodontitis.

Inclusion Criteria:

• Age 18 years or older.
• Advanced periodontitis, defined as stage 3-4 periodontitis or grade B/C periodontitis according to clinical and radiographic assessment during routine dental care.
• Ability to understand study information and provide informed consent.

Exclusion Criteria:

• Previously diagnosed diabetes mellitus.
• Inability to provide informed consent, for example due to severe mental disorder or markedly impaired health status as judged by the clinical staff.