Figure 4: The concept of a hyperbolic Disposition Index as a predictor of progression to t2d DI is defined as a product of SI and AIRg, DI=SI* AIRg and is illustrated as a two dimensional hyperbola with AIRg as an ordinate and SI as an abscissa. The hyperbolic relationship between SI and AIRg allows for the small changes in any component to be compensated by small changes in the other component for the hyperbola value to stay constant i.e. small changes in SI are compensated by the AIRg or vice versa - blue line. An adequate compensatory change result in a constant hyperbola, however, the worsening compensation will result in lowering of DI value and will indicate a progression to t2d – red line. Improvement of the either component beyond compensation will lead to higher DI value indicating metabolic improvement (27 and references within).