Methods of Assessment of Insulin Sensitivity and β-Cell Function

Assessment of insulin sensitivity and β-cell function is required in many studies, as these characteristics are of fundamental importance in glucose intolerance and diabetes, and insulin sensitivity is also a potential underlying cause of other pathologies. Clinical investigations on the pathophysiological role of these factors and on the efficacy of drugs for disease prevention and treatment thus necessitate a variety of methods, suitable for the specific needs of each study. Scope of this review is to present critically and in an integrated fashion the methods that are currently in use for the assessment of insulin sensitivity, β-cell function and their relationships. As the considered methods differ in the degree of experimental complexity and reliability, their characteristics are comparatively discussed to provide guidelines for a correct choice and application. It is suggested that the choice of the insulin sensitivity method basically depends on the experimental constraints, as reliability and experimental complexity are inversely related. The assessment of βcell function is more problematic, as the βcell response is complex and only partially understood. The existing methods often provide β cell function indices that quantify different characteristics of the βcell, and cannot be ranked on a unique scale. It is however suggested that the βcell function methods, and in particular the techniques for the study of the relationships between insulin sensitivity and βcell function, should be critically used to avoid inappropriate application and conclusions.