Quantitative Aspects of Subcutaneous Insulin Absorption

Subcutaneous insulin absorption is a complex process, whose quantitative aspects have important clinical implications. In this review we briefly discuss the rationale of modelling techniques before introducing some of the more common types of models (empirical vs mechanistic, simple vs complex, compartmental) found in the biological literature. The various approaches are compared regarding their suitability to model subcutaneous absorption of insulin. Methods are described (monitoring residual depot activity or the appearance of insulin in the systemic circulation) which allow the determination of model parameters from experimental data. The degree to which current model predictions describe the available experimental data is discussed. Since the absorption of insulin involves a number of poorly understood events it would be difficult, at this time, to construct a complex model which completely describes all aspects of the absorption process. Although the simpler techniques (such as the use of a one-pool model) provide only an approximate description of subcutaneous kinetics they are likely to remain useful tools in routine investigation.