Supplementary Material for: Testing Multiple Delivery Methods of the Virtual Exercise Games for Youth with T1D (ExerT1D) Peer Intervention: Protocol Development and Feasibility

Background: Adolescents with type 1 diabetes (T1D) face barriers to moderate-to-vigorous physical activity (MVPA) such as uncertainty with self-management, limited access to supportive environments, and stigma related to living with diabetes. Opportunities for peer activities with T1D role model support are limited. To address this need, we tested iterative refinements of pilot Virtual Exercise Games for Youth with T1D (ExerT1D) for feasibility and acceptability. Methods: The program included 6 versions: study 1 (1.1-1.4) included an active videogame, and study 2 (2.1-2.2) included a virtual reality active videogame. All versions included T1D exercise management education by clinicians and goal-setting guided by young adult coaches with T1D. Results: Seventeen adolescents (median age 15.4 [IQR 14.6-16.4] years, 7 non-Hispanic white, 8 male, median HbA1c 8.1% [IQR 7.4%-11.1%]) enrolled. Participants rated the program, comfort, clinicians, coaches, and group cohesion high/very high. Motivation for the videogame was high . Building T1D and MVPA self-management skills was rated excellent at most sessions, as were peer interactions and enriched communication after adding immersive virtual reality in study 2. Transitions between VR apps caused delays of 19±6 minutes per 60min-90min session. Compared to baseline, HbA1c or Glucose Management Indicator (GMI) decreased over time in an exploratory analysis (d=-1.12, 90% CI [-1.78,-0.48]). Conclusions: In a small cohort, the ExerT1D program facilitated a supportive environment for engaging diverse youth with T1D in an MVPA program led by T1D coaches. Larger studies are needed to assess the intervention’s impact on engagement with physical activity, glycemic outcomes, and quality of life.