Repeatability of the hyperglycaemic clamp for assessment of β-cell response and insulin sensitivity in horses.
Authors: Lindåse S, Johansson H, Månsby M, Bröjer J
Journal: Equine veterinary journal
Summary
# Editorial Summary: Hyperglycaemic Clamp Repeatability in Horses Whilst the hyperglycaemic clamp has established utility for measuring insulin sensitivity in equine practice, its application to assess pancreatic β-cell function and the reliability of both measures remain poorly characterised. Lindåse and colleagues conducted a longitudinal study in which six Standardbred mares underwent two hyperglycaemic clamps separated by a 10-day interval, permitting calculation of coefficient of variation (CV) and intraclass correlation coefficients (ICC) for derived indices of insulin sensitivity and glucose-stimulated insulin secretion. β-cell response measures demonstrated excellent repeatability, with area under the insulin curve (0–120 min and 60–120 min steady state) and mean steady-state insulin concentration showing CVs between 9.3–10.5% and ICCs of 0.93–0.95. Glucose disposal (M-value) exhibited lower repeatability (CV 12.4%, ICC 0.71), whilst the derived insulin sensitivity index (M/I) showed intermediate reliability (CV 17.4%, ICC 0.89). These findings validate the hyperglycaemic clamp as a robust diagnostic tool for characterising β-cell secretory capacity in the clinical setting, though practitioners should recognise that insulin sensitivity quantification via this method carries greater measurement variability and may require serial testing for meaningful detection of physiological change. The modest sample size warrants cautious extrapolation, but the results provide a useful reference framework for interpreting single and repeated clamp studies in metabolic evaluations.
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Practical Takeaways
- •The hyperglycaemic clamp can be confidently used to assess pancreatic beta-cell function in clinical or research settings, as measurements are highly repeatable between test occasions
- •If using this test to evaluate insulin sensitivity, expect greater variability in results; consider this when interpreting changes or comparing individual horses over time
- •This test provides a validated objective method for horses suspected of metabolic disorders, though the technique requires specialist equipment and expertise
Key Findings
- •Beta-cell response measures showed high repeatability with coefficient of variation 9.3-10.5% and intraclass correlation coefficient 0.93-0.95
- •Insulin sensitivity (M/I-index) had lower repeatability with CV 17.4% and ICC 0.89 compared to glucose disposal alone (CV 12.4%, ICC 0.71)
- •The hyperglycaemic clamp is a reliable diagnostic method for assessing beta-cell response but shows moderate reliability for insulin sensitivity measurement in horses