INS and diabetes mellitus: This close relationship between insulin sensitivity and insulin secretion follows a hyperbolic curve, and the multiplication product of these two parameters is known as the DI.9 The DI therefore reflects beta-cell function relative to the prevailing insulin sensitivity,29 and predicts incident diabetes beyond fasting and 2-h glucose levels.19, 20 In prospective epidemiology studies, individuals who progressed from normoglycemia to T2DM exhibited the ‘falling off the DI curve' phenomenon, indicating a failure of insulin secretion to compensate for the degree of insulin resistance.20