Automatic Tuning of CIR and ISF with the Adaptive Bolus Calculator (ABC) Approach Is Safe and Reliable—Results from a Hybrid In Silico Evaluation

Abstract

Introduction: T1DM patients usually determine their bolus insulin requirements using a patient and daytime specific carbohydrate to insulin ratio (CIR) and insulin sensitivity factor (ISF). These factors are tuned by the patients themselves with assistance of their MDs. Recently, the Adaptive Bolus Calculator (ABC) method has been proposed for the automatic tuning of CIRs and ISFs based on data that is routinely collected by T1DM patients. Methods: Data from a recent clinical trial with 12 patients are used for evaluating the ABC method. CIR and ISF values are identified using the ABC method based on the first 6 days of the data, whereas the 7th day is used for the evaluation. The effect of the estimated CIRs and ISFs on the glycemic outcomes is simulated using a deviation based method. The simulation outcomes are compared to the outcomes obtained with the clinically used settings (in the figure below abbreviated as CUS) that the patients employed on the previous 6 days for calculating their bolus insulin needs. Results: The CIRs and ISFs estimated by the ABC approach lead in average to a 6.8% reduction for time in hypoglycemia (BG<70 mg/dl) as compared to the clinically used CIR/ISF settings (avg. time in hypoglycemia: from 9.8% to 3.0%, p<0.01). Time in hyperglycemia (BG>180 mg/dl) on the other hand increases only slightly (avg. time in hyperglycemia: 10.9% vs. 9.3%, p=0.08). Disclosure F. Reiterer: None. L. del Re: None.