Evidence-based estimation of insulin resistance.

Insulin resistance is a complex phenotype. Surrogate markers based on peripheral glucose and insulin (and in some cases NEFA) concentrations can provide, at best, moderate approximations to direct physiological measurements (Pearson r values 0.6-0.7). Where the focus is solely on insulin resistance, the evidence reviewed in the paper by Otten et al in this issue (DOI: 10.1007/s00125-014-3285-x ) suggests that surrogate markers based on fasting samples alone are as valid as those that require multiple samples and an oral glucose load. This provides an evidence base for simplifying the design of some clinical studies.