The above-mentioned studies have established the hyperbolic relationship between insulin sensitivity and insulin secretion in humans. Since the comprehension of this relationship is fundamental for the understanding of pathogenesis of type 2 diabetes, there is a need to develop experimental tools for studying this relationship. In 1998 it was shown that it is possible to use the FSIGT in experiments in mice (17). The technique involves, as in humans, a rapid i.v. injection of glucose which is followed by repeated sampling of blood for analysis of insulin and glucose. The number of samples was reduced in mice, and it was shown that by taking seven samples over 50 min, reliable measures of insulin secretion and insulin sensitivity were obtained after modeling the data with, for example, the SI value showing a good correlation with the insulin sensitivity as obtained from the euglycemic hyperinsulinemic clamp technique (18). Also in mice, a hyperbolic relationship was evident when plotting insulin sensitivity vs insulin secretion (18, 19) and therefore also in mice it was possible to calculate a disposition index. This has offered a tool for experimental analysis of the mechanisms regulating the interrelationships between insulin action and secretion and for studies of potential treatment modalities in mice (20).