Implementation of a new insulin model covering both injection and pump delivery in DiasNet

The core of DiasNet is a discrete differential model of the human carbohydrate metabolism with two compartments modeling carbohydrate content in the gut and blood glucose. In the present model, blood insulin is calculated from standard absorption profiles, which are modified by dose/peak relations for each insulin type. This may be appropriate for insulin injections, but calculating blood insulin levels in patients using continuous insulin infusion seems less appropriate in such a "single-shot" model. Therefore, a new prototype insulin model has been implemented. It is a discrete difference model with two main parts modeling subcutaneous insulin and blood insulin. The subcutaneous insulin part is divided into sub-compartments modeling the association state of insulin (low and high molecular weight, i.e. hexameric and dimeric) and the subcutaneous diffusion, leading to the required absorption characteristics; for example, the initial slow absorption and volume and concentration dependencies for regular and long-acting insulin. In the blood insulin compartment, representing both the blood stream and extra vascular space, insulin is degraded according to a first order process. Incorporating this new insulin model, DiasNet can be used by diabetics and healthcare professionals to illustrate the effect of changing insulin regimes and pump settings on blood glucose levels.