Value of measuring markers of lipid metabolism in horses during an oral glucose test.
Authors: Zemek Claire H K, Kemp Kate L, Bertin François-René
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Lipid Metabolism Markers During Oral Glucose Testing in Horses Equine Metabolic Syndrome (EMS) presents diagnostic challenges, particularly in distinguishing between hyperinsulinaemia and true insulin resistance. This cross-sectional study investigated whether measuring triglycerides and non-esterified fatty acids (NEFA) during an oral glucose test (OGT) could provide additional diagnostic value beyond standard insulin and glucose assessment. Twenty horses—comprising seven with hyperinsulinaemia and insulin resistance (HI-IR), four with hyperinsulinaemia alone, and nine controls—underwent OGT with blood sampling at 0, 60, 90 and 120 minutes to measure lipid metabolism markers alongside glucose and insulin responses. The OGT significantly suppressed both triglycerides (falling from 0.35 to 0.25 mmol/L) and NEFA (from 0.1 to 0.05 mEq/L) across all horses, reflecting the expected metabolic shift to carbohydrate utilisation. Crucially, HI-IR horses demonstrated substantially elevated triglyceride and NEFA areas under the curve compared to controls (79.46 versus 33.32 mmol/L·min for triglycerides; 9.1 versus 6.0 mEq/L·min for NEFA), whereas hyperinsulinaemic non-resistant horses showed no significant lipid differences from controls. These findings suggest that impaired suppression of lipolysis during glucose challenge reflects peripheral tissue insulin resistance rather than elevated insulin secretion alone. For practitioners, incorporating lipid measurements into OGT protocols may refine identification of true insulin resistance and better guide metabolic management strategies in horses suspected of EMS.
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Practical Takeaways
- •Measuring triglyceride and NEFA responses during oral glucose testing may help identify horses with tissue insulin resistance, potentially aiding in earlier detection of Equine Metabolic Syndrome
- •Hyperinsulinemia alone without insulin resistance does not appear to alter lipid metabolism patterns during glucose challenge, suggesting different metabolic pathways may be involved
- •Lipid markers during OGT could complement existing diagnostic protocols for metabolic screening in horses showing signs of metabolic syndrome
Key Findings
- •Oral glucose testing significantly reduced triglyceride concentrations from 0.35 to 0.25 mmol/L and NEFA concentrations from 0.1 to 0.05 mEq/L across all horses (P=0.005 and P=0.0009 respectively)
- •Hyperinsulinemic insulin-resistant horses had significantly higher triglyceride AUC (79.46 vs 33.32 mmol/L*min, P=0.01) and NEFA AUC (9.1 vs 6.0 mEq/L*min, P=0.03) compared to control horses
- •Hyperinsulinemic non-insulin-resistant horses showed no significant lipid metabolism differences from control horses during OGT