Aim: To determine whether a nurse telephone follow-up service could improve the level of adherence to a diabetes therapeutic regimen for patients with type 2 diabetes. Methods: A total of 61 patients attended a 3 day diabetes self-care program at the Iranian Diabetes Society. They were randomly assigned to one of the experimental or control groups. A telephone follow-up program was applied to the experimental group for 3 months, twice per week for the first month and weekly for the second and third months. The data-collection instruments included a data sheet to record the glycosylated hemoglobin (HbA1c) level and a questionnaire. The data were collected at baseline and after 12 weeks. Results: There were significant differences between the control and the experimental groups in their adherence to a diabetic diet, exercise, foot care, blood glucose monitoring, and medication-taking. Also, the HbA1c levels differed significantly between the two groups after 3 months. Conclusion: A nurse-led telephone follow-up was effective in enhancing the level of adherence to a diabetes therapeutic regimen, such that the HbA1c level decreased.