BACKGROUND Adequate self-care in diabetes causes quality of life promotion and decreases the number of inpatient cases. The health locus of control theory is used to assess adherence to diabetes regimen in some studies in developed countries. The purpose of this study was to determine the status of diabetes locus of control in a sample of diabetic patients in Iran and investigation of it's relationship to adherence to diabetes regimen. METHODS This analytical and cross-sectional study was carried out on 120 patients referred to Yazd Diabetes Research Center. The Iranian versions of Diabetes Locus of Control scale and Diabetes Selfcare Activities scale were used for data collection. RESULTS Men were more internal locus of control and women were more chance locus of control. The attributions of external locus of control increased by age, while the internal locus of control increased by education level and chance locus of control decreased by education level. A positive association between internal locus of control and adherence to diabetes regimen was found and there was a negative association between chance locus of control and adherence to diabetes regimen. CONCLUSIONS Findings suggest that interventions aimed at improving internal locus of control may improve adherence to diabetes regimen but different diabetic patients have different attribution styles and interventional programs to enhance diabetes self-care will be more successful if patient's locus of control is addressed.