Periodontitis and diabetes are complex chronic diseases, linked by an established bidirectional relationship. Risk for periodontitis is increased two to three times in people with diabetes compared to individuals without, and the level of glycaemic control is key in determining risk. In people who do not have diabetes, periodontitis is associated with higher glycated haemoglobin (HbA1c) and fasting blood glucose levels, and severe periodontitis is associated with increased risk of developing diabetes. In people with type 2 diabetes, periodontitis is associated with higher HbA1c levels and worse diabetes complications. Treatment of periodontitis in people with diabetes has been shown to result in improved glycaemic control, with HbA1c reductions of 3-4 mmol/mol (0.3-0.4%) in the short term (3-4 months) post-treatment. Given that treatment of periodontitis results in clinically relevant reductions in HbA1c, the dental team has an important role in the management of patients with diabetes. Improved interprofessional working in relation to diabetes and periodontitis has been advocated by professional and scientific organisations, though practical and systemic barriers make this challenging. This paper reviews current evidence linking periodontitis and diabetes, and considers the role of the dental team in the wider context of management of patients with diabetes and periodontitis.