Video-Based Lifestyle Counseling in Adults With Type 2 Diabetes.

Type 2 diabetes mellitus (DM2) is a major global public health challenge associated with increased morbidity and mortality. Lifestyle modification is a cornerstone of treatment; however, long-term adherence remains limited. Digital health interventions offer scalable and accessible tools to improve self-management and behavioral change.

This prospective, multicenter, randomized controlled trial will evaluate a video-based lifestyle intervention. A total of 156 adults with DM2 under routine medical follow-up will be recruited from healthcare centers in Sagunto and Castellón (Spain) and randomly assigned (1:1) to one of two parallel groups.

The experimental group will receive the intervention through audiovisual content delivered by their own physician, while the control group will receive identical content delivered by physicians unknown to the participants. The intervention consists of structured multimedia modules focusing on nutrition, physical activity, strength exercise, and psychological strategies to support behavior change.

Assessments will be conducted at baseline and immediately after the 3 month intervention. Additional follow up assessments are planned at 6 and 12 months. The study explores how extent the physician's identity influences glycated hemoglobin / HbA1c (primary outcome), body mass index, blood pressure, glycemic and lipid metabolism variables, physical activity level, adherence to the Mediterranean diet, therapeutic alliance, and health-related quality of life.

• Video-based lifestyle intervention (own physician) (Behavioral): The experimental group will receive the video-based lifestyle intervention delivered by their own physician, while the control group will receive identical content delivered by physicians unknown to the participants. The intervention consists of structured multimedia modules focusing on nutrition, physical activity, strength exercise, and psychological strategies to support behavior change.
• Video-based lifestyle intervention (unknown physician) (Behavioral): The experimental group will receive the video-based lifestyle intervention delivered by their own physician, while the control group will receive identical content delivered by physicians unknown to the participants. The intervention consists of structured multimedia modules focusing on nutrition, physical activity, strength exercise, and psychological strategies to support behavior change.

Primary outcomes

• Glycated Hemoglobin (HbA1c) [Baseline (pre-intervention) and 3 months (post-intervention)]: HbA1c (%) will be used as the primary measure of glycemic control. It reflects average blood glucose levels over the previous 2-3 months and will be obtained from venous blood samples analyzed in routine clinical laboratories.

Secondary outcomes

• Body Mass Index (BMI) [Baseline and 3 months]: BMI will be calculated as weight divided by height squared (kg/m²).
• Blood Pressure (Systolic and Diastolic) [Baseline and 3 months]: Measured in mmHg following standardized clinical guidelines.
• Lipid Profile [Baseline and 3 months]: Total cholesterol, HDL, LDL, and triglycerides (mg/dL).
• Physical Activity Level (IPAQ-SF) [Baseline and 3 months]: Levels of Physical Activity will be assessed using the Short International Physical Activity Questionnaire (Short-IPAQ). This tool evaluates the frequency, duration, and intensity of physical activity, as well as sedentary behavior, in daily life. It estimates total physical activity in METs-min/week and records time spent sitting, providing a standardized measure of physical activity levels.
• Adherence to Mediterranean Diet (MEDAS) [Baseline and 3 months]: Adherence to the Mediterranean Diet will be assessed using the MEDAS (Mediterranean Diet Adherence Screener) from the PREDIMED study. This 14-item questionnaire evaluates adherence based on 12 questions about food consumption frequency and 2 questions on dietary habits associated with the Mediterranean diet. Each item is scored 0 or 1 point, with a total possible score ranging from 0 to 14 points. Higher scores indicate greater adherence.
• Therapeutic Alliance (WAI) [Baseline and 3 months]: Therapeutic Alliance will be assessed using the Working Alliance Inventory (WAI) questionnaire. This tool evaluates the relationship between a patient and their therapist across three key dimensions: (1) therapeutic goals, (2) tasks, and (3) therapeutic bond. Each item is scored on a Likert scale, with a total possible score ranging from low to high alliance strength. Higher scores indicate a stronger therapeutic alliance, which is associated with better treatment outcomes.
• Health-Related Quality of Life (EQ-5D-3L) [Baseline and 3 months]: Health-Related Quality of Life (HRQoL) will be assessed using the EuroQol-5D (EQ-5D) questionnaire. This tool evaluates five dimensions of health: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression, each rated on a multi-level scale. A health index score will be generated based on these dimensions. The visual analog scale (VAS) will not be used in this study.

Sex: All, ages: 18 Years to 65 Years

Inclusion Criteria:

* Adults aged 18-65 years
* Diagnosis of type 2 diabetes mellitus
* Under medical follow-up in participating centers
* Access to the internet and a smartphone
* Ability to provide informed consent

Exclusion Criteria:

* Pregnancy
* Type 1 diabetes or other specific forms of diabetes
* Severe acute or unstable medical condition
* Contraindication to diet or exercise
* Severe psychiatric disorder
* Eating disorder
* Physical disability limiting physical activity
* Participation in another structured weight-loss or lifestyle program
* No medical visit in the last 2 years