Biological Variation of Homeostasis Model Assessment-Derived Insulin Resistance in Type 2 Diabetes
- Vijay Jayagopal, MRCP1,
- Eric S. Kilpatrick, MRCPATH2,
- Paul E. Jennings, FRCP13,
- David A. Hepburn, FRCP1 and
- Stephen L. Atkin, FRCP1
- 1Department of Medicine, University of Hull, Hull, U.K
- 2Department of Clinical Biochemistry, Hull Royal Infirmary, Hull, U.K
- 3Department of Medicine, York District General Hospital, York, U.K
Abstract
OBJECTIVE—Individuals with type 2 diabetes are particularly vulnerable to cardiovascular disease. Insulin resistance is a major determinant of this increased risk and is a potential therapeutic target. This study was undertaken to establish the natural biological variation of insulin resistance in individuals with type 2 diabetes.
RESEARCH DESIGN AND METHODS—The biological variation of insulin resistance was assessed by measuring insulin resistance at 4-day intervals on 10 consecutive occasions in 12 postmenopausal women with diet-controlled type 2 diabetes and in 11 weight- and age-matched postmenopausal women without type 2 diabetes. Insulin resistance was derived using the homeostasis model assessment for insulin resistance (HOMA-IR) method.
RESULTS—The distribution of HOMA-IR was log Gaussian in the type 2 diabetic study group and Gaussian in the control group. The HOMA-IR in the type 2 diabetic group was significantly greater than that of the control group (mean ± SD: 4.33 ± 2.3 vs. 2.11 ± 0.79 units, P = 0.001). After accounting for analytical variation, the mean intraindividual variation was also substantially greater in the type 2 diabetic group than in the control group (mean 1.05 vs. 0.15, P = 0.001). Consequently, at any level of HOMA-IR, a subsequent sample must increase by >90% or decrease by >47% to be considered significantly different from the first.
CONCLUSIONS—HOMA-IR is significantly greater and more variable for individuals with type 2 diabetes. Therefore, this inherent variability needs to be accounted for in studies evaluating therapeutic reduction of HOMA-IR in this group.
Footnotes
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Address correspondence and reprint requests to Dr. V. Jayagopal, Michael White Centre for Diabetes and Endocrinology, Brocklehurst Building, Hull Royal Infirmary, 220-236 Anlaby Rd., Hull, HU3 2RW, U.K. E-mail: v.jaygopal{at}hull.ac.uk.
Received for publication 7 February 2002 and accepted in revised form 22 July 2002.
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