PROJECT ABSTRACT Comorbid overweight/obesity (BMI>85th percentile for sex and age) was rare in youth with type 1 diabetes mellitus (T1DM) prior to the 1990s, but the prevalence now exceeds that of youth in the general population. Behavioral weight management interventions are evidence-based, first-line treatments for pediatric obesity. Yet, there are unique challenges of T1DM that require thoughtful adaptations to these interventions. Examples include reduced exercise and excess calorie consumption due to hypoglycemia. Adolescents with T1DM and comorbid overweight/obesity are also at high risk of developing disordered eating behaviors. There is a critical need for behavioral weight management interventions that address barriers specific to T1DM and incorporate attention to eating disorder prevention in this at-risk population. The objective of this K23 project is to adapt the primary mentor’s (Dr. Elissa Jelalian) established 16-week adolescent weight management intervention for a T1DM population. Using the Obesity-Related Behavioral Intervention Trials (ORBIT) model, a framework for intervention development, this project will design, refine, and test an adapted behavioral weight management intervention for adolescents with comorbid T1DM and overweight/obesity using two related yet distinct studies. Study 1 will ensure feasibility (i.e., participant attendance) and acceptability of intervention materials by adolescents with comorbid T1DM and overweight/obesity using an open-trial design with 2-3 small groups (n=5 adolescents/group). Participants will complete validated measures of acceptability after each weekly session and an exit survey post-intervention. The Candidate will iteratively refine the intervention based upon Study 1 results. Study 2 will compare the adapted weight management intervention to a usual care control group using a pilot randomized controlled trial design (n=50 total adolescents) to verify that the adapted intervention reduces participant BMI and increases the percent time spent in the target blood glucose range (70-180mg/dL; primary outcomes). Participants in Study 2 will complete ecological momentary assessments (EMA) at baseline and 16-weeks to determine events of maladaptive eating and weight control behaviors over time (secondary outcomes). Exploratory analyses will evaluate correlates of these maladaptive eating and weight control behaviors in real-world settings. This K23 project builds upon the Candidate’s prior work in pediatric obesity and T1DM. The highly qualified and expert mentorship team will provide support and oversight, allowing the Candidate to acquire the necessary skills to launch an independent research career aimed at improving weight management for adolescents with comorbid T1DM and overweight/obesity. Results will provide data for a subsequent application to conduct a fully powered randomized controlled trial to test the efficacy of the adapted weight management intervention. The proposed project aligns with the NIDDK’s mission to mitigate diabetes-related cardiovascular events and has the potential to be an important public health intervention to improve the health of adolescents with T1DM and overweight/obesity.

PROJECT NARRATIVE The combined prevalence of overweight and obesity in youth with type 1 diabetes mellitus (T1DM) is now greater than the prevalence of combined overweight and obesity in youth of the general population, and increased weight in youth with T1DM increases risk factors for cardiovascular health problems. This K23 project will adapt an established behavioral weight management intervention for adolescents with overweight/obesity for a T1DM population. Study results and the Candidate’s training plan will inform a larger efficacy trial evaluating this novel evidence-based behavioral weight management intervention for adolescents with T1DM and overweight/obesity and will launch the Candidate’s career as an independent clinical investigator.