Methods to assess in vivo insulin sensitivity and insulin secretion

The assessments of insulin sensitivity/resistance and of insulin secretion/beta cell function in humans are still significant challenges. The interest for these traits stems from their proved, or presumed, implications in a great number of pathological conditions, such as obesity, type 2 diabetes, atherosclerosis, non alcoholic fatty liver disease (NAFLD), Alzheimer’s disease. A wide number of tests and surrogate indexes have been developed and applied in many experimental and observational settings to gauge exact values for each of these two traits. In this chapter the general principles underlying the assessments of insulin sensitivity and of beta cell function are reviewed, and the most popular tests are described with their pros and cons.