699-P: Prerandomization Factors Associated with Time-in-Target Glucose Range with Hybrid Closed-Loop Use in a Six-Month Randomized Controlled Trial in Adults with Type 1 Diabetes

Background: In our published trial in 120 adults with type 1 diabetes (T1D), allocation to hybrid closed loop (HCL) increased Continuous Glucose Monitoring (CGM) Time in Range ((TIR), 70-180mg/dL) by 15 percentage points vs. user-determined insulin dosing. Recommended TIR is >70%. Objective: To examine associations of pre-randomization factors with trial-end 3-weeks masked CGM TIR in adults with T1D treated with 6-months HCL. Methods: MDI and non-HCL pump users (no CGM) were randomized 1:1 to 26-weeks HCL (Medtronic 670G) or ongoing standard care. Analyses are on HCL group (n=55): Pre-randomization factors are related to trial-end masked CGM TIR >70 vs. ≤70% and to TIR as a continuous variable. Continuous variables are compared by t-test and binary variables by chi-square with significance at P vs. ≤70%. Significant univariate correlations between trial-end TIR as a continuous variable existed for pre-randomization factors: HbA1c (at enrolment and randomization), 1,5-anhydroglucitol, CGM metrics: %TIR (70-180mg/dl), %TIR (70-140mg/dl), mean glucose, SD glucose. Conclusions: The main factor associated with HCL users achieving higher TIR was pre-randomization glycemia. TIR was not associated with age, sex, prior pump use and socioeconomic status.