Comparison of a customized glycemic pellets challenge with the oral sugar test to measure glycemic and insulinemic responses in horses.
Authors: Thane Kristen, Sonntag Johanna, Warnken Tobias, Reiche Dania, Uricchio Cassandra, Frank Nicholas
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Glycemic Pellets Challenge as an Alternative to Oral Sugar Testing in Horses Insulin dysregulation diagnostics rely heavily on provocative testing, yet the low-dose oral sugar test (OST), whilst practical, has limitations in standardization and palatability across individual horses. Researchers compared a newly formulated glycemic pellets challenge (GPC)—delivering 0.5 g glycemic carbohydrates per kilogram body weight—against the established OST (0.15 mL corn syrup/kg) in 24 adult horses of unknown insulin status using a randomized crossover design with blood sampling at multiple timepoints and radioimmunoassay insulin analysis. Eighteen horses readily consumed >85% of GPC pellets within 10 minutes, with both tests producing measurable glycaemic and insulinaemic responses; notably, GPC elicited significantly higher peak glucose (P = .02) and insulin concentrations (P = .007) compared to OST, though time to maximum insulin concentration varied unpredictably within and between tests regardless of consumption rate. For practitioners selecting between diagnostic modalities, the GPC offers superior palatability and more pronounced metabolic perturbation, potentially improving sensitivity for detecting subclinical insulin dysregulation; however, the variable timing of peak insulin secretion across horses suggests that single-timepoint sampling may be inadequate, and clinicians should consider collecting samples across extended intervals (ideally to 180 minutes) to reliably capture diagnostically relevant insulinaemic changes.
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Practical Takeaways
- •GPC may be a useful additional tool for screening horses with suspected insulin dysregulation, though it produces higher insulin responses than OST so reference ranges will need to be established
- •Timing of blood sample collection is critical for both tests; a single time point may miss diagnostically important insulin peaks, so multi-point sampling protocols are necessary
- •Most horses readily consume the pellets, making GPC practical for field use, though individual variation in insulin response timing requires careful protocol standardization
Key Findings
- •Glycemic pellets challenge (GPC) produced significantly higher maximum glucose (P = 0.02) and insulin (P = 0.007) concentrations compared to low-dose oral sugar test (OST)
- •18 of 24 horses consumed >85% of GPC pellets within 10 minutes, demonstrating good tolerance of the test
- •Time to maximum insulin concentration (Tmax[ins]) varied within and between both tests, with no correlation to pellet consumption speed (P = 0.28)
- •GPC offers a viable alternative diagnostic modality for insulin dysregulation testing with different glucose/insulin kinetics than OST