## 3 Materials and Methods  
### Description of the MR Application  
Our MR application is designed for patients with Type 1 diabetes, allowing direct interaction with virtual food in a real-life environment. Thanks to the passthrough technology of the Meta Quest 2 and Meta Quest 3 headsets, patients can visualize food in their real environment and manipulate it with their own hands (Figures 1 and 2). The real environment is displayed in color (Meta Quest 3) or grayscale (Meta Quest 2), but the virtual elements embedded in the scene are displayed in color on both devices (Figures 1 and 2). The application detects the position and movements of the hands, allowing users to pick up the virtual food, examine it from different angles, and facilitate a better understanding of the carbohydrate choices. The immersive approach makes it easier for patients to focus on the learning task.  
The use of hands as a visual and physical reference in an MR environment enhances understanding of proper portion size. By interacting with 3D models superimposed on the real world, users can easily compare suggested portions with those they might consume. The patients completed the following steps. A graphical summary of the steps is shown in Figure 3.  
1. Enter personal details. To start, the patients are required to provide their age and gender. Based on this information, the application then displays the recommended carbohydrate choices per day and specifically for breakfast, where 1 carbohydrate choice equals 15 g of carbohydrates. This standard is widely used in Ecuador, Mexico, the United States, and most of Latin America, though it differs in some other countries. For instance, in Spain, 1 carbohydrate choice equals 10 g, while in Austria, it equals 12 g.
2. The MR application is organized into three levels, each focusing on a different food category: the first level covers dairy products, the second level addresses grains, and the third level focuses on fruits. The first level includes 7 foods, the second level presents 8 foods, and the third level consists of 10 foods. At each level, a realistic simulation of the foods is presented, allowing for tactile interaction, and the content is organized in two phases: (a) the learning phase, where patients observe the foods in real size and can see their name, quantity, weight, glycemic index, carbohydrate choices, and homemade portions of food, like a cup or tablespoon (these details are provided by the Foundation in its educational resources) (Figure 4); (b) the assessment phase, where the patients must remember the learning information. Each of the 25 foods is shown, and the patient is required to choose the correct number  
Figure 1: Two examples of virtual food manipulation with the user’s hands using color passthrough.  
Figure 2: Virtual food manipulation with the user’s hands using grayscale passthrough.  
of carbohydrate choices from the three available options (Figure 5). The application then informs the patient whether the answer is correct or not. The decision to provide three options for selection was made to speed up the process, as requiring the patient to write the carbohydrate choices for each food item would significantly increase the time needed for a learning session.  
Figure 4: Example of the learning phase at level 3.  
Figure 3: A visual overview outlining the steps to be followed by the patients.