Practical application of methods for in vivo assessment of insulin secretion and action

In vivo measurement of insulin sensitivity can be made using the glucose clamp technique or the intravenous glucose tolerance test (IVGTT) with minimal model analysis. The glucose clamp provides a direct, readily understandable measure of insulin action but is more demanding for investigators and subjects. Assessment of insulin secretion must be made by a separate test. The IVGTT is easier to perform but the data are more difficult to analyse and the value for insulin sensitivity is a derived rather than direct measure. As well as insulin sensitivity, glucose mediated glucose disposal and insulin secretion are measured by the IVGTT. In fact the IVGTT technique relies on adequate endogenous insulin secretion whereas the glucose clamp does not. The choice between these two techniques depends on the study to be performed and the available laboratory facilities.