BackgroundType 1 diabetes is a chronic disease with complex therapeutic recommendations that require day-to-day lifestyle changes. People with type 1 diabetes need to be involved in their health care in order to achieve satisfactory control of the condition. Motivational Interviewing is a communication tool that has been shown to be effective in changing behaviors in people with addictions, obesity and type 2 diabetes.Our objective is to evaluate the impact of a Motivational Interviewing intervention in patients with type 1 diabetes, through a randomized controlled clinical trial.MethodsSixty-six patients with type 1 diabetes and hemoglobin A1c>= 8% have been included and randomly assigned (computer-generated sequence, sealed envelopes, ratio 1:1) either to the intervention group or to the control group. In the intervention group, appointments every four months with the endocrinologist include Motivational Interviewing; in the control group, the appointments proceed as usual. Patients will be followed for 16 months.The primary outcome will be self-care behaviors, assessed according to a validated questionnaire, the Diabetes Self-Care Inventory-Revised Version. Secondary outcomes include: HbA1c, motivation for self-care, self-efficacy, health-related quality of life, satisfaction with professional-patient relationship, fulfillment of patients' own objectives and other sociodemographic and clinical variables related to disease control.The practitioners will receive training in Motivational Interviewing in order to help them promote adherence to self-care, encourage patient motivation and improve the doctor-patient relationship. The Motivational Interviewing intervention will be evaluated through videorecordings of the sessions and the administration of a purpose-built questionnaire, the EVEM 2.0 scale, by two psychologists, blinded to the assigned treatment. DiscussionThere is evidence that MI can improve self-care in type 2 diabetes. In T1D, however, its application has focused on adolescents, but, at present, there are no published data on the effect of MI in adults with T1D. In this study, we aim to evaluate the effect of MI on self-care and HbA1c.