Introduction and Objective: Insulin sensitivity factor (ISF) is often considered constant in Automated Insulin Delivery systems and other insulin therapies, but ISF varies with glycemia [1]. This study assesses the impact of glycemia (G) on ISF using real-life data.Methods: Data from 11,201 T1D adults using the DBLG1 System since March 2021 was used. G peaks were extracted from days with at least 75% of closed loop, occurring after at least 1h post meal, with COB < 2.5g and G in [50, 400] mg/dL. A G minimum (Gmin) was identified after each peak (Gmax), with a maximum to minimum interval larger than 20min. Then, ISF was calculated as: ISF = (Gmax – Gmin) / CI where CI is the consumed insulin between tmin and tmax, with CI = IOB(tmax) − IOB(tmin) + ∫tmin to tmax (basal(t) + bolus(t) − basalref(t)) dt. IOB is insulin-on-board, basal and bolus are insulin delivered, and basalref is the reference basal rate.Results: Figure 1 shows ISF variation: ISF increases from 65 to 79 mg/dL/U as G rises from 50 to 100 mg/dL, then declining to 35 mg/dL/U at G = 180 mg/dL and below 20 mg/dL/U for G > 300 mg/dL. Insulin doses for G > 340 mg/dL may double compared to a reference ISF of 35 mg/dL/U at G = 180 mg/dL, to account for reduced ISF, while for G ≤ 120 mg/dL doses could be halved to reflect increased ISF.Conclusion: This study highlights glycemia-dependent ISF variability, providing insights to refine insulin therapy and enhance closed-loop systems for better glucose control.
H.M. Romero-Ugalde: Employee; Diabeloop SA. A. Adenis: Employee; Diabeloop. T. Cartier-Michaud: None. P. Gauthier: Employee; Diabeloop. C. Desir: Employee; DIABELOOP. T. Le Roux-Mallouf: Employee; Diabeloop. E. Huneker: Employee; Diabeloop. P.Y. Benhamou: Employee; Diabeloop SA. Board Member; Eli Lilly and Company, Insulet Corporation, Novo Nordisk.
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