Objective: This study aimed to assess the impact of health literacy and patient empowerment on diabetes self-care behaviour in patients in metropolitan Turkish diabetes centres. The conceptual background is provided by the psychological health empowerment model, which holds that health literacy without patient empowerment comes down to wasting health resources, while empowerment without health literacy can lead to dangerous or suboptimal health behaviour. Design, setting and participants: A cross-sectional study was conducted with 167 patients over the age of 18 from one of two diabetes clinics in a major Turkish City. Self-administered questionnaires were distributed to eligible outpatients who had an appointment in one of the clinics. Health literacy was measured by a newly translated Turkish version of the Short Test of Functional Health Literacy in Adults (S-TOFHLA) and the Chew self-report scale. Patient empowerment was measured by a 12-item scale based on Spreitzer's conceptualisation of psychological empowerment in the workplace. Self-care behaviour was measured by the Self-care behaviours were measured by the Summary of Diabetes Self-Care Activities Measure (SDSCA). Level of diabetes knowledge was measured by Diabetes Knowledge Test. Results: Two subscales of empowerment, impact and self-determination, predicted self-reported frequency of self-care behaviours. Neither health literacy nor diabetes knowledge had an effect on self-care behaviours. Conclusions: Health literacy might be more effective in clinical decisions while empowerment might exert a stronger influence on habitual health behaviours.