In recent decades several diseases primarily associated with obesity have reached epidemic proportions and many of them such as high blood pressure, hyperlipidaemia and type 2 diabetes mellitus, are already an important social problem. It has been calculated that in 2030 type 2 diabetes mellitus per se will be responsible of 3% of deaths in the world together with ischaemic heart disease and cerebrovascular disease, which will account for 13 and 11% of all cause of deaths.1 Non-invasive, low-cost, easy to perform and reproducible diagnostic tools have been used in epidemiological studies to allow the screening of large populations. While the assessment of fasting glycaemia, oral glucose tolerance test blood pressure, and serum cholesterol and triglycerides is routine in clinical practice, the use of a hyperinsulinaemic–euglycaemic clamp in every patient with type 2 diabetes mellitus is clearly not feasible. Since the diagnostic accuracy, assessed by the value of the area under the receiver operator characteristic curve (ROC), of all 19 candidate indexes of insulin resistance to predict incident diabetes varies from 0.75 to 0.8,2 these variables are extensively used both in clinical practice and trials.

A very similar scenario occurs in clinical hepatology. Fatty liver (FL) or hepatic steatosis is a very common finding …