Fig 1.

The Disposition Index (DI) is the product of insulin secretion and insulin sensitivity. Normally, increases in insulin resistance (due to factors such as weight gain and inactivity) are matched by a compensatory increase in insulin secretion in a hyperbolic relationship (A to B) and DI remains constant. Inadequate insulin secretion to compensate for insulin resistance results in a reduction in DI and impaired glucose homeostasis (A to C) and eventually to type 2 diabetes (A to D). (Data adapted from: Bergman RN, Phillips LS, Cobelli C. Physiologic evaluation of factors controlling glucose tolerance in man: measurement of insulin sensitivity and beta-cell glucose sensitivity from the response to intravenous glucose. J Clin Invest. 1981;68(6):1456–67) [9].