It has been reported that a close association exists between inflammatory periodontal diseases and diabetes through which one exerts a reciprocal influence on the other. This two-way relationship is based on the extensively reported assumption that the one condition so modifies the systemic and local environments that the progress of the other is favoured. On the other hand, treating and eliminating inflammatory periodontal diseases results in improved glycaemic control which minimises the microvascular complications of diabetes. This paper provides a brief review in an endeavour to create a better understanding of the interaction between these two relatively common conditions.