Evaluation of Proposed Oral Disposition Index Measures in Relation to the Actual Disposition Index

Diabet Med. 2009 Dec;26(12):1198-203. doi: 10.1111/j.1464-5491.2009.02841.x.

Abstract

Aims While the disposition index provides a useful measure of B-cell function, its calculation requires the performance of a frequently sampled intravenous glucose tolerance test (FSIVGTT). Recently, the demonstration of a hyperbolic relationship between indices of insulin secretion and insulin sensitivity derived from the oral glucose tolerance test (OGTT) has led to the introduction of two novel OGTT-based measures of B-cell function analogous to the disposition index: (i) the insulin secretion-sensitivity index-2 (ISSI-2) (defined as the ratio of the area-under-the-insulin-curve to the area-under-the-glucose curve, multiplied by the Matsuda index) and (ii) insulinogenic index (IGI)/fasting insulin. However, neither of these two measures has been directly compared with the disposition index. Methods Two hundred and thirteen non-diabetic children (122 boys, 91 girls) underwent both OGTT and FSIVGTT, allowing for the calculation of ISSI-2, IGI/fasting insulin and the disposition index. Results ISS1-2 and IGI/fasting insulin were strongly correlated with each other (r = 0.82, P < 0.0001). Both measures correlated with the disposition index, with ISSI-2 showing a modestly stronger association (ISSI-2: r = 0.24, P = 0.0003; IGI/fasting insulin: r = 0.21, P = 0.0022). Standardized linear regression analyses confirmed that the relationship between log ISSI-2 and the disposition index (standardized regression coefficient = 0.224, P = 0.001) was stronger than that between log IGI/fasting insulin and the disposition index (standardized regression coefficient = 0.166, P = 0.015). Conclusions The OGTT-derived measures ISSI-2 and IGI/fasting insulin exhibit modest correlations with the disposition index. These relationships require further assessment in other patient populations.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Area Under Curve
  • Blood Glucose / metabolism*
  • Child
  • Diabetes Mellitus / diagnosis*
  • Fasting
  • Female
  • Glucose Tolerance Test*
  • Humans
  • Insulin / blood
  • Insulin / metabolism*
  • Insulin Resistance
  • Insulin Secretion
  • Linear Models
  • Male
  • Predictive Value of Tests
  • Sensitivity and Specificity

Substances

  • Blood Glucose
  • Insulin