The automated correction index (ACI), a novel report-derived metric correlated to glucose control and variability in patients with type 1 diabetes on advanced hybrid closed loop therapy

Objective: This study aimed to correlate the parameters of advanced hybrid closed loop (AHCL) function to the glycometabolic outcomes in a cohort of patients with type 1 diabetes (T1D) using different AHCL systems. Research design and methods: This was a retrospective cross-sectional study on 124 adult (n = 87) and pediatric (n = 37) patients correlating the total daily insulin dose (TDD), the total daily basal (TDBa) and bolus (TDBo) insulin doses, the percentage of auto-bolus out of total daily bolus (Automated Correction Index − ACI) to the glycated hemoglobin (HbA1c) and the sensor-derived metrics. Results: The ACI was the only AHCL-derived parameter directly associated to HbA1c (p = 0.03) and time above range (TAR180-250 mg/dL, 10-13.9 mmol/L, p < 0.01), and inversely correlated to time in range (TIR70-180 mg/dL, 3.9-10 mmol/L, p < 0.01). Patients with ACI < 30 % showed reduced HbA1c levels (6.21 % ± 0.5 vs. 6.95 % ± 0.8, p = 0.02) and a higher probability of having TIR > 70 % (OR 3.18, CI 1.19–8.46, p = 0.02) and coefficient of variation (CV) < 36 % (OR 2.86, CI 1.07–8.27, p = 0.03) compared to those with ACI ≥ 30 %. Conclusion: The ACI could represent a useful and easy-to-assess metric for AHCL-treated individuals with T1D. In our cohort an ACI < 30 % was associated to better glucose control and variability.