Modeling glucose metabolism in man: theory and practice

Quantitative assessment of whole-body and regional glucose metabolism from in vivo kinetic data requires a model of the system, i.e. specific assumptions about the structure and functioning of the system. We discuss here models which allow the measurement and understanding of the kinetics of glucose metabolism in vivo in man and of the effect of insulin upon them. Discussed models include: a whole-body description of glucose distribution and metabolism to quantitate insulin effect; a model to measure in vivo glucose transport in the forearm; physiological models to assess glucose kinetics in the non-steady state; the insulin and C-peptide IVGTT minimal models to assess beta-cell function; the labelled IVGTT minimal models to assess insulin sensitivity and hepatic production. Emphasis is on models of the compartmental type and on the crucial role of modeling methodology. Aspects of improved experiment design are also discussed.