Hypoglycemia Prevention via Personalized Glucose-Insulin Models Identified in Free-Living Conditions

Abstract

Background: The objective of this research is to show the effectiveness of individualized hypoglycemia predictive alerts (IHPAs) based on patient-tailored glucose-insulin models (PTMs) for different subjects. Interpatient variability calls for PTMs that have been identified from data collected in free-living conditions during a one-month trial.

Methods: A new impulse-response (IR) identification technique has been applied to free-living data in order to identify PTMs that are able to predict the future glucose trends and prevent hypoglycemia events. Impulse response has been applied to seven patients with type 1 diabetes (T1D) of the University of Amsterdam Medical Centre. Individualized hypoglycemia predictive alert has been designed for each patient thanks to the good prediction capabilities of PTMs.

Results: The PTMs performance is evaluated in terms of index of fitting (FIT), coefficient of determination, and Pearson's correlation coefficient with a population FIT of 63.74%. The IHPAs are evaluated on seven patients with T1D with the aim of predicting in advance (between 45 and 10 minutes) the unavoidable hypoglycemia events; these systems show better performance in terms of sensitivity, precision, and accuracy with respect to previously published results.

Conclusion: The proposed work shows the successful results obtained applying the IR to an entire set of patients, participants of a one-month trial. Individualized hypoglycemia predictive alerts are evaluated in terms of hypoglycemia prevention: the use of a PTM allows to detect 84.67% of the hypoglycemia events occurred during a one-month trial on average with less than 0.4% of false alarms. The promising prediction capabilities of PTMs can be a key ingredient for new generations of individualized model predictive control for artificial pancreas.

Keywords: artificial pancreas; hypoglycemia prevention; model identification; safety system.

Figure 1.

Example of true positive (a), true negative (b), false positive (c), and false negative (d) of prediction by individualized hypoglycemia predictive alert. In each panel, the continuous glucose monitoring (CGM) measured before the considered time instant $k^{*}$ (magenta), the future real CGM measurements (dashed pink) and the glucose prediction obtained via the patient-tailored glucose-insulin models used in the individualized hypoglycemia predictive alert (dashed blue) are shown. At each sample time, the individualized hypoglycemia predictive alert state is reported (gray/red square); if present, hypoglycemia events with their detection windows are shown.