Objective: To investigate the effect of dental treatments on the glycaemic control of type 2 diabetes. Methods: At baseline, 105 patients with poorly controlled type 2 diabetes (glycated haemoglobin HbA1c >= 8%) were recruited. Dental treatments were provided and the subjects were reviewed at three-monthly intervals. At 12 months, 83 patients remained in the treatment group. Sixty type 2 diabetic patients who had not received any dental treatment during the past 12 months were recruited into the comparison group. Results: The HbA1c level of the treatment group subjects decreased from 9.0% at baseline to 8.1% at evaluation (paired t-test; p 0.001). The reduction was higher than that in the comparison group over the same period, 0.9% versus 0.3% (t-test; p 0.01). Analysis of covariance showed that receipt of dental care was related to a reduction in HbA1c level (p = 0.001). Conclusion: Provision of dental treatment and maintenance of good oral health contribute to an improvement in glycaemic control in patients with type 2 diabetes. Keywords: diabetes mellitus, dental treatment, Chinese, Hong Kong, clinical trial