Abstract

The main aim of this research was to test if fractional-order differential equation models could give better fits than integer-order models to continuous glucose monitoring (CGM) data from subjects with type 1 diabetes. In this research, real continuous glucose monitoring (CGM) data was analyzed by three mathematical models, namely, a deterministic first-order differential equation model, a stochastic first-order differential equation model with Brownian motion, and a deterministic fractional-order model. CGM data was analyzed to find optimal values of parameters by using ordinary least squares fitting or maximum likelihood estimation using a kernel-density approximation. Matlab and R programs have been developed for each model to find optimal values of the parameters to fit observed data and to test the usefulness of each model. The fractional-order model giving the best fit has been estimated for each subject. Although our results show that fractional-order models can give better fits to the data than integer-order models in some cases, it is clear that the models need further improvement before they can give satisfactory fits.

Highlights

  • 1 Introduction Insulin and glucagon are hormones that are produced in the pancreas and which control the level of glucose in the blood

  • If blood glucose is high, the pancreas secretes insulin into the bloodstream to decrease glucose level

  • 3 Fractional differential equation models Because the first-order models do not fit the data, we look at higher-order models

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Summary

Introduction

Insulin and glucagon are hormones that are produced in the pancreas and which control the level of glucose in the blood (see, e.g., [ – ]). Type is sometimes called non-insulin-dependent or adult-onset diabetes In this type, the pancreas either produces insufficient insulin with respect to the heightened demands of relatively insulin-resistant peripheral tissues or the cells of the body do not react to Sakulrang et al Advances in Difference Equations (2017) 2017:150. . The fit using ordinary least-squares gives a constant value for G(t) and an estimate for the ratio of parameter values kGX kXG and not separate values for kGX and kXG, i.e., it gives the steady-state solution of equation ( ). Numerical solution using the Euler-Maruyama method requires a step size that is much smaller than the time ( minutes) between measurements in the CGM data. The first-order models do not give a good fit to the CGM data They have been useful for developing R-programs and testing some of the algorithms to be used in the stochastic fractional differential equation models. For < α ≤ , the initial value of the second derivative G( )( ) is required to uniquely specify the solution

Numerical solution of deterministic model
Discussion
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