Assessment of insulin secretion in relation to insulin resistance

PURPOSE OF REVIEW: In healthy individuals, upregulation of insulin secretion compensates for insulin resistance so that normal glucose tolerance is maintained. Thus insulin secretion should be evaluated in relation to insulin sensitivity, as failure to account for insulin resistance may prevent the detection of beta-cell defects. Numerous studies have considered this problem, but how insulin secretion is regulated by insulin sensitivity and how insulin secretion should be quantitatively expressed to account for sensitivity are issues still under debate. This review will discuss these concepts and the aspects that should be considered for an appropriate solution to the problem. RECENT FINDINGS: While the historical paradigm of a specific hyperbolic relationship between some particular insulin secretion and insulin sensitivity indices has recently been confirmed, it has been suggested that this paradigm is not applicable to all the indices. It has also been suggested that for some relevant insulin secretion indices this relationship may not exist. Thus, the classical insulin secretion index that accounts for sensitivity, the so-called disposition index, should be used cautiously, as it presupposes a hyperbolic relationship. Furthermore, it has been pointed out that the assessment of this relationship requires independency of the indices. SUMMARY: The assessment of insulin secretion in relation to insulin sensitivity is important in the study of glycemic control but requires appropriate methods and cautious interpretations. Blind application of principles that are valid for specific insulin secretion and sensitivity indices may produce false results.