Enhancing glucose sensor models: modeling the drop-outs.

BACKGROUND

Computer simulation environments have been used in the development of many artificial pancreas systems. A glucose sensor model is an essential part of these environments, and different models have been proposed. However, not one of these models accounts for drop-outs of sensor readings, a well-known phenomenon caused by physical pressure on the sensor site. In this work, we have proposed an enhanced model that accounts for drop-outs and demonstrated its improvement over the existing one-compartment model.

MATERIALS AND METHODS

Potential drop-outs were augmented to the existing model, and their incidences and magnitudes were estimated simultaneously with the model parameters using the Bayesian approach. Drop-outs and model parameters were estimated from data collected from 15 subjects with type 1 diabetes who underwent an artificial pancreas study. Model fitting and parameter estimates were contrasted between the enhanced model and the existing one-compartment model.

RESULTS

Both models achieved similar parameter estimates (P=not significant) and were all physiologically plausible. The enhanced model further estimated 1.71 drop-outs per day, which improved model fit (weighted residual reduced from [minimum -4%, maximum 3%] to [-3%, 2%]) and reduced significantly the deviance information criteria from 2739.72 to 1456.00.

CONCLUSIONS

The enhanced model improves fitting of glucose levels and should allow more realistic simulations that assesses artificial pancreas systems.