Evaluation of a Reduced Sampling Schedule for Assessment of Pancreatic Beta-Cell Function with the Intravenous Glucose Tolerance Test During a Dietary Intervention

Pancreatic beta-cell function is a key determinant of glucose tolerance. The intravenous glucose tolerance test (IVGTT) can be used to assess both the insulin sensitivity index (Si) and the acute insulin response to glucose (AIRg). The disposition index (DI = Si × AIRg) reflects the adequacy of pancreatic beta-cell response for the level of insulin sensitivity. The aim of this analysis was to compare the AIRg and DI values calculated using a reduced early test sampling schedule (t = 0, 5, 10 min), to those from the full sampling schedule (t = 0, 3, 5, 7, and 10 min). Participants included men (n = 8) and women (n = 16) with mean (SD) age 48.9 (9.9) y and body mass index 30.8 (4.9) kg/m2. Subjects consumed 0, 15, and 30 g/d high-amylose resistant starch (RS) for 4 weeks each, in a double-blind, randomized, crossover trial, and underwent a 180-min IVGTT at the end of each treatment period. The Minmod Millenium program was used to derive Si. AIRg was calculated as the mean increment in plasma insulin during ...