Insulin receptor binding to blood cells: an outdated concept for clinical studies on insulin resistance?

Clinical data on insulin binding to blood cells contribute to our present knowledge of insulin resistance. Binding data have been frequently presented to indicate alterations in insulin action. It is now evident that insulin binding data are of limited value for our understanding of insulin resistance. This is mainly due to the tissue-specific binding of insulin as well as the "pleiotypic" nature of insulin action. As insulin action is determined at (a) the "pre-" receptor level, (b) the receptor, and/or (c) different postbinding sites, it is unlikely that receptor data alone can explain defective insulin action. As knowledge of the molecular biology of insulin receptor morphology and function as well as of the action of insulin on intermediary metabolism increases, clinicians should not be further overloaded with binding data. Nevertheless, binding data on blood cells may be still of some value in investigating patients with severe insulin resistance due to genetic disorders of the insulin receptor or insulin receptor autoantibodies.