Background: Diabetes self-management education programmes which have been reported to improve the self-efficacy of diabetic people can lead to their empowerment. Specialized diabetes nurses also play a fundamental role in empowering patients with diabetes through improving their knowledge and self-care. Aim: The purpose of this study was to develop a valid and reliable questionnaire to measure empowerment in Iranian people with type 2 diabetes. Methods: Important subscales of patient empowerment were identified by an expert panel. The subscales included active self-care, coping with personal and social concerns, basic knowledge related to diabetes management and patient-physician communication. Questions related to each subscale were generated and the expert panel renewed the questionnaire to ensure relevance and clarity of the items. Patient focus groups were conducted to establish the face validity of the questionnaire. The final questionnaire consisted of 15 items organized in three subscales. In a population-based study, a sample of 378 people with type 2 diabetes was recruited. Reliability coefficient (Cronbach's α) was calculated for all of the subscales. Convergent validity was assessed by Pearson's product moment correlation. The scree test was used to select significant subscales. Findings: Two hundred forty-seven female and 131 male subjects with type 2 diabetes filled out the questionnaire. Three subscales were derived from factor analysis considering item-component loading of 0.4 as significant: 'active self-care' (Cronbach's α: 0.78), 'basic knowledge related to diabetes management' (Cronbach's α: 0.72) and 'coping with personal and social concerns' (Cronbach's α: 0.51). The scree plot of the eigenvalues of 15 items proposed three subscale solutions. Internal consistency reliabilities for the three subscales were acceptable (α: 0.51-0.78). Conclusions: The Diabetes Empowerment Questionnaire is a reliable and valid tool to assess patient empowerment in Iranian people with type 2 diabetes.