Trial Design and Participants
This was a prospective, randomized, open-label, parallel-group, single-center pilot study. The trial was conducted at the tertiary medical center of Korea University Anam Hospital. Through the Hana Center, a representative welfare center for North Korean refugees supported by the South Korean government, we recruited North Korean refugee volunteers aged 19-59 years who were able to use smartphones. The volunteers visited Korea University Anam Hospital and were screened for eligibility.A flow diagram of the study design is shown in At the first visit (visit 1), all participants underwent anthropometric measurements, including height, weight, and waist circumference (WC) measurements; blood pressure measurements; and blood tests, including the fasting blood sugar (FBS), glycated hemoglobin (HbAThe Fitbit Charge 3, along with the corresponding application, was provided to all participants during the first visit. The participants were taught how to use the Fitbit device and were asked to wear it continuously until the end of the study. Compliance with wearing the Fitbit device was checked at weeks 2 and 4.We divided the participants into 2 groups: an intervention group (who wore the Fitbit device and received individualized health counseling based on the Fitbit data) and a control group (who wore the Fitbit device but did not receive individualized counseling). Block randomization was performed in a 1:1 ratio to stratify the participants according to age and sex. The intervention group visited the hospital during week 4 (visit 2) and received a daily record of the step count, sleep duration, and calorie consumption. On the basis of these Fitbit data, a medical professor of endocrinology provided individualized counseling on physical activity and recommended the type, intensity, and frequency of exercise. At week 8, the intervention group received additional health counseling based on Fitbit data via telephone calls.The end-of-trial visit was conducted at week 12 (visit 3), and both groups underwent anthropometric measurements, blood pressure measurements, and laboratory assessments. They were administered the same questionnaire regarding dietary habits and physical activity as that administered during the first visit. The Fitbit data collected over 12 weeks were used in the analyses.Flow diagram of the study design. 