Feasibility and Preliminary Efficacy of a "Sit Less" Program Leveraging Fitbit Tracking and Tailored Text Messages in Cardiometabolic Disease: Findings From 2 Parallel Randomized Controlled Trials in Coronary Artery Disease and Type 2 Diabetes.

Individuals with cardiometabolic disease typically average 10 to 14 hours of daily sedentary time, which increases the risk of cardiovascular disease. This study aimed to evaluate the feasibility, acceptability, and preliminary efficacy of a "Sit Less" program in reducing sedentary behavior in people with cardiometabolic disease. Participants with cardiovascular disease or type 2 diabetes underwent separate randomization into the Sit Less intervention or the control group. Sit Less included 1 in-person counseling session, a Fitbit, a smart water bottle, and tailored weekly text messages for 12 weeks. Control group participants received the American Heart Association's "Answers by Heart" booklet. Sedentary behavior was measured using the activPAL for 7 days at baseline and postintervention. The secondary outcomes included physical activity, cardiometabolic biomarkers, continuous glucose monitoring metrics, and psychological factors. Generalized linear models estimated adjusted between-group differences, controlling for baseline values, cohort, cohort×group interaction, and leisure-time exercise. Of the 37 randomized participants, 35 (95%) completed the study (Sit Less: n=17, 48.6%; and control: n=18, 51.4%). Of the 35 participants who completed the study, 62% (n=21) were men, the median age was 67 (54-72) years, and their baseline sedentary time was approximately 10.4 hours per day. Sit Less participants demonstrated high adherence, including a text response rate of 81% and a median Fitbit wear time of 15 hours per day on 6.8 days per week, and 15 (88%) of 17 participants reported satisfaction with the program. Compared with the control group, Sit Less participants showed greater reductions in total sedentary time (adjusted mean difference -17.3 min/d, 95% CI -63 to 28; P=.45) and prolonged sedentary time of >30 minutes (-39.5 min/d, 95% CI -100 to 21; P=.20) and >60 minutes (-49.9 min/d, 95% CI -102 to 2; P=.06) and increases in sit-to-stand transitions (4.2 per day, 95% CI -2 to 10; P=.13), although none were statistically significant. Hemoglobin A1c was lower in the Sit Less group than in the control group (adjusted mean difference -0.4%, 95% CI -0.8 to -0.1; P=.04). Continuous glucose monitoring outcomes, including mean glucose (-6.0 mg/dL, 95% CI -14.9 to 2.8; P=.18) and time in range (2.1%, 95% CI -4.8 to 9.1; P=.54), were not statistically significant but demonstrated similar directional changes. Other cardiometabolic biomarkers, physical activity, and psychological outcomes were not significantly different, except for lower self-efficacy for moderate physical activity in the Sit Less group (-0.6, 95% CI -1.1 to -0.2; P=.003). The Sit Less intervention was feasible and acceptable and showed possible improvements in sedentary behavior and glycemic outcomes. Although this pilot study had a small sample size and limited statistical power, with multiple outcomes examined and wide CIs observed, these findings support evaluation in larger, adequately powered trials.