Measurement of insulin resistance in vivo.

Insulin sensitivity, which can be impaired in both glucose-intolerant and non-glucose-intolerant individuals, is a valuable parameter because of its potential as a marker for the future development of diabetes and increased cardiovascular risk. Techniques available for the determination of insulin sensitivity include the glucose clamp, insulin tolerance test, insulin suppression test, the frequently sampled intravenous glucose tolerance test and the regional artero-venous balance. Model assessment methods are also available for the measurement of insulin sensitivity at steady-state plasma glucose and insulin levels or after a standardised glucose infusion. Methods vary in their complexity, and the choice between them depends on the nature of the information required. There is also evidence for a strong genetic contribution to insulin sensitivity; although identification of the relevant gene(s) has not yet been successful, accurate phenotyping should still be carried out as part of the assessment of a patient's clinical status.