Original Research

Assessing the test–retest repeatability of insulin resistance measures: Homeostasis model assessment 2 and oral glucose insulin sensitivity

Catherine A.P. Crofts, Mark C. Wheldon, Caryn Zinn, Xiaomiao Lan-Pidhainy, Thomas M.S. Wolever, Grant Schofield
Journal of Insulin Resistance | Vol 2, No 1 | a27 | DOI: https://doi.org/10.4102/jir.v2i1.27 | © 2017 Catherine A.P. Crofts, Mark C. Wheldon, Caryn Zinn, Xiaomiao Lan-Pidhainy, Thomas M.S. Wolever, Grant Schofield | This work is licensed under CC Attribution 4.0
Submitted: 18 August 2017 | Published: 31 October 2017

About the author(s)

Catherine A.P. Crofts, Faculty of Health and Environmental Sciences, Auckland University of Technology, New Zealand
Mark C. Wheldon, Faculty of Health and Environmental Sciences, Auckland University of Technology, New Zealand
Caryn Zinn, Faculty of Health and Environmental Sciences, Auckland University of Technology, New Zealand
Xiaomiao Lan-Pidhainy, Division of Nutritional Sciences, Cornell University, United States
Thomas M.S. Wolever, Department of Nutritional Sciences, University of Toronto, Canada
Grant Schofield, Faculty of Health and Environmental Sciences, Auckland University of Technology, New Zealand


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Abstract

Background: Insulin resistance is commonly assessed using the homeostasis model assessment (HOMA) variants. HOMA is potentially insensitive to change because of its high coefficient of variation. The repeatability coefficient is an alternative means of assessing test repeatability. To be confident of clinical change, rather than biological variation, a subsequent test needs to differ from the former by more than the repeatability coefficient using the equation.

Test 1 = Test 2 ± repeatability coefficient.

The repeatability coefficients for measures of insulin resistance are unknown.

Aim: To compare the repeatability coefficient of HOMA2 variants (Beta-cell function [%B], insulin sensitivity [%S], insulin resistance [IR]) to a dynamic measure of insulin resistance, and the oral glucose insulin sensitivity (OGIS) test.

Setting: The raw data from a previously used data set were reanalysed.

Methods: Glycaemic and insulinaemic tests were performed on 32 men and women both with (n = 10) and without type 2 diabetes (n = 22). From these data, eight fasting tests and three 50-g oral glucose tolerance tests were used to calculate HOMA2 and OGIS. The methods of Bland and Altman assessed repeatability.

Results: Repeatability coefficients for all participants for the HOMA2 %B, %S and IR variants were 72.91, 189.75 and 0.9, which equates to 89%, 135% and 89% of their respective grand means. By contrast, OGIS had a repeatability coefficient of 87.13, which equates to 21% of the grand mean.

Conclusion: Because of the high repeatability coefficient relative to the grand mean, use of HOMA2 measures for assessing insulin resistance in small population studies should be reconsidered.


Keywords

HOMA; insulin resistance; OGIS; repeatability

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