The Preparation Phase
After recruiting and screening the participants based on the inclusion and exclusion criteria, the uniformly trained researchers introduced the purpose, procedures, benefits, potential risks, inconveniences, and discomfort of the study to the participants. The participants signed an informed consent form when they agreed to participate. The participants were randomly divided into 3 groups: group DPI, group PI, and group C. Next, the participants in groups DPI and PI were trained on the smartphone health management app, activity tracker, and other intervention measurements that needed to be coordinated. After opening an app account number for the participants, the researchers helped them download and log into the app; taught them to use the app, activity tracker, and standardized meal; and instructed them on the methods and steps of monitoring their weight, blood pressure, blood glucose, etc. They allowed the participants to practice using the app to record and upload their data and photos on dietary intake and physical activity, as well as their weight, blood pressure, blood glucose, and other monitoring data. Group C participants maintained their previous lifestyle.