Introduction: Non-adherence to treatment is a common problem in diabetic patients. Nurse-led Telephone follow-up by nurses can be effective in maintaining consistent care to these patients and improving their knowledge and performance. The purpose of the present study was to investigate the effect of nurse-led telephone follow-up on adherence to treatment in patients with type 2 diabetes. Materials and Methods: The present quasi-experimental study was conducted on 60 patients with type 2 diabetes, admitted to a diabetes clinic in Aligudarz, Iran. Samples were selected using the convenience sampling method and randomly divided into the experimental and control groups. All participants first received 3 days of diabetes self-care training, and the experimental groups had twelve weeks of telephone follow-ups. Data on the patients’ glycosylated hemoglobin and treatment adherence were collected at baseline and again 12 weeks after the intervention. Results: Results obtained showed a significant increase in the mean scores of treatment adherence and reduction of 1.39% in the mean glycosylated hemoglobin levels of the experimental group (p<0.001). Conclusion: Findings of the present study showed nurse-led telephone follow up is an effective method for improving glycemic control and adherence to treatment in patients with type 2 diabetes.