Fully Closed-Loop Improves Glycemic Control Compared with Pump with CGM in Adolescents with Type 1 Diabetes and HbA1c Above Target: A Two-Center, Randomized Crossover Study.

Introduction: Adolescents with type 1 diabetes (T1D) can struggle to reach recommended HbA1c targets more than other age groups. The safety and efficacy of fully closed-loop (FCL) insulin delivery, which does not require mealtime bolusing, have not been assessed in this cohort. We evaluated the use of FCL with faster insulin aspart (Fiasp) in adolescents with T1D whose HbA1c was above recommended targets. Materials and Methods: This two-center, randomized, crossover study included 24 adolescents (13-19 years) using insulin pump therapy with above-target HbA1c (mean age 16.2 years, median HbA1c 74 mmol/mol [8.9%]). Participants underwent two 8-week periods of unrestricted living, comparing FCL (CamAPS HX) with Fiasp, with standard nonautomated insulin pump therapy with continuous glucose monitoring (CGM), in random order. Results: In an intention-to-treat analysis, the percentage of time glucose was in target range (primary endpoint 3.9-10.0 mmol/L) was higher during FCL than during pump with CGM use (mean ± standard deviation [SD]) 45.2% ± 7.2% vs. 32.3% ± 12.8%, mean difference 12.9 percentage points, 95% confidence interval [CI] 8.5 to 17.3, P < 0.001). Time spent in hyperglycemia >13.9 mmol/L and mean glucose were lower with FCL compared with pump with CGM (median time >13.9 mmol/L 28.7% vs. 39.6%, difference -7.3 percentage points, 95% CI -11.1 to -3.5, P < 0.001; mean glucose 11.1 mmol/L vs. 12.7 mmol/L, difference -1.2 mmol/L, 95% CI -1.8 to -0.5, P < 0.001). Proportion of time with glucose <3.9 mmol/L was similar between interventions (median: FCL 2.78% vs. pump with CGM 2.97%, difference -0.34 percentage points, 95% CI -1.03 to 0.35, P = 0.322). There was no difference in HbA1c after FCL compared with pump with CGM (median: 71 mmol/mol (8.6%) vs. 74 mmol/mol (8.9%), P = 0.227). There was no difference in total daily insulin dose (P = 0.276). No severe hypoglycemia or ketoacidosis occurred. Conclusions: FCL insulin delivery with CamAPS HX improved glucose outcomes compared with insulin pump therapy with CGM in adolescents with T1D and HbA1c above target.