Surrogate measures of insulin resistance: does one size fit all?

Insulin resistance and a relative deficiency in insulin secretion are the major pathophysiological features of impaired glucose tolerance and type 2 diabetes. Although the euglycaemic-hyperinsulinaemic clamp and the hyperglycaemic clamp are the 'gold standards', respectively, for measuring these metabolic defects, there has been an active search during the past few decades for simpler and less expensive surrogate measures of insulin resistance that can be applied more globally in epidemiological studies or large clinical trials. These surrogate markers primarily rely on plasma insulin and glucose levels measured either in the fasting state or after an oral glucose challenge. Although many of these surrogate measures correlate well with the clamp (with r values frequently as high as 0.60-0.70) within racially and ethnically homogeneous populations, it is not clear how well they can be used to compare insulin action across different groups. In this issue of Diabetologia, Ahuja et al have used these methods to compare insulin resistance in a white population in the USA with a Japanese population in Japan. The relative merits and drawbacks of applying these techniques in different populations are discussed.