USE OF A PRIORI AND A POSTERIORI METHODOLOGIES TO INFORM THE DEVELOPMENT OF FEASIBLE EATING STRATEGIES THAT PROMOTE GLYCEMIC MANAGEMENT IN YOUNG PEOPLE WITH TYPE 1 DIABETES

There are no evidence-based eating strategies for youth with type 1 diabetes, despite established understanding that nutrition is fundamental to glycemic management and complication prevention, and self-management is worse during adolescence compared to all other life stages. Critically, existing eating strategies do not provide guidance related to timing, frequency, or macronutrient composition of eating occasions to optimize short-term or longer-term glycemic measures. The objective of this dissertation was to inform the development of eating strategies that consider these factors, with the ultimate goal of prospectively evaluating their effectiveness for improving of glycemic management among youth with type 1 diabetes. In Aim 1, we developed a daily eating behavior pattern focused on number and timing of eating occasions and distribution of macronutrients throughout the day, and conducted a pilot trial to explore feasibility and diabetes management benefits among 52 adolescents with type 1 diabetes. We observed excellent retention (85%), attendance (15.8[SD=0.6]/16 sessions), food log adherence (4.0[SD=2.6]/≥3 logs per week), ≥90% participation in evaluation procedures, and no adverse effects. Endline adherence to most (≥3) goals was ≥90% according to unannounced dietary recalls. Hemoglobin A1c decreased on average by 0.3(SD=0.9)% (p=0.03). Youth and parents (>85%) endorsed acceptability. Findings supported progression to a trial to evaluate effectiveness. Aim 2 was a secondary analysis using 175 days of overlapping eating, insulin, physical activity, continuous glucose monitoring, and clinical data from 49 participants in the Aim 1 trial. We trained a generalized additive model that incorporated predictors over a 6-hour window divided into 1-hour intervals (-2 to -1 hours, -1 to 0 hours, 0 to +1 hours, +1 to +2 hours, +2 to +3 hours, +3 to +4 hours), to predict near-term time in range (0 to +4 hours). We demonstrated a proof-of-concept for the intended application of the model: a personalized, adaptive eating decision support tool that enables users to select from meals/snack options and adjust timing to optimize near-term glycemic management amidst food or timing constraints. Our studies lay groundwork for the development of behaviorally interpretable, specific and feasible eating strategies that youth with type 1 diabetes can use to support day-to-day management.