Study protocol for a randomized clinical trial evaluating the effectiveness of a Brazilian lifestyle-based diabetes prevention program: the PROVEN-DIA trial

Type 2 diabetes (T2D) affects more than 16 million Brazilians and has nearly doubled in the last 20 years. Lifestyle interventions reduce T2D incidence in people at risk of developing the disease; however, no large-scale trials have evaluated diabetes prevention programs in Brazil or compared telehealth and hybrid delivery in middle-income settings. These are key gaps that must be addressed to enable nationwide scale-up, particularly in primary care settings and remote areas. This article presents the protocol for the PROVEN-DIA trial, designed to address these evidence gaps. PROVEN-DIA is a multicenter, open-label, randomized controlled superiority trial with a parallel design enrolling 1,305 adults with prediabetes at 30 sites across all five Brazilian regions (ClinicalTrials.gov: NCT06426277). Participants will be randomly assigned in equal numbers to one of three groups. All groups receive lifestyle guidance targeting diet, physical activity, sleep, stress, alcohol consumption, and smoking, in accordance with Brazilian national guidelines. The two intervention groups receive PROVEN-DIA, a structured 36-month lifestyle program with 43 scheduled contacts encompassing individual counseling sessions, structured support contacts, and group education sessions, delivered either in a hybrid format (PROVEN-DIA) or telehealth only (TelePROVEN-DIA). The control group receives the same lifestyle guidance through unstructured individual visits every six months, without predefined content or ongoing support. The primary outcome is the cumulative incidence of type 2 diabetes at 36 months. Secondary outcomes include body weight, fasting glucose, glycated hemoglobin (HbA1c), dietary quality, physical activity, sedentary behavior, sleep quality, perceived stress, alcohol consumption, smoking behavior, and health-related quality of life. Analyses will follow the intention-to-treat principle.