A good treatment for type 1 diabetes mellitus (T1DM) requires accurate measurements of blood glucose levels. Continuous glucose monitors (CGM) measure the glucose concentration in the interstitial fluid of the abdominal subcutaneous adipose tissue. However, glucose measured in abdominal interstitial fluid does not accurately represent blood glucose concentrations due to the complex blood transport through the body and glucose diffusion in interstitital fluid. Methods: A phenomenological-based semi-physical model (PBSM) of the glucose transport by volumetric flow and diffusion from the bloodstream to interstitial fluid was constructed to gain insight into this problem. In this regard, a published tenstep modeling procedure is used to obtain a model for the transport time of glucose through the blood vessels and from the blood capillaries to the interstitial fluid, the diffusion of glucose within the interstitial fluid, and the diffusion of glucose through the semipermeable coating.