Numerical Simulation of Insulin Depot Formation in Subcutaneous Tissue
In this study a numerical model of the insulin depot formation and absorption in the subcutaneous adipose tissue is developed using the commercial Computational Fluid Dynamics (CFD) software ANSYS Fluent. A better understanding of these mechanisms can be helpful in the development of new devices and cannula geometries as well as predicting the concentration of insulin in the blood. The injection method considered in this simulation is by the use of an insulin pump using a rapid acting U100 insulin analogue. The insulin is injected into the subcutaneous tissue in the abdominal region. The main composition of the subcutaneous tissue is blood vessels and adipose cells surrounded by interstitial fluid. The numerical simulation is conducted in a 2D-axisymmetric domain where the tissue is modeled as a fluid saturated porous media. Due to the presence of channel formation in lateral direction in the tissue, an anisotropic approach to define the permeability is studied having an impact on the viscous resistance to the flow. This configuration is resulting in a rather disk shaped depot following recent experimental findings. The depot formation is analyzed running Bolus injections ranging from 5–15 Units of insulin corresponding to 50–150μl. The depot formation model has been extended implementing the process of absorption of insulin from the depot to be able to run the simulation over longer timeframes where absorption starts playing an important role.