Value of measuring markers of lipid metabolism in horses during an oral glucose test.

Abstract

BACKGROUND: Characterizing the lipid response to an oral glucose test (OGT) might improve our understanding of Equine Metabolic Syndrome. HYPOTHESIS/OBJECTIVES: To describe the effects of an OGT on lipid metabolism and determine the value of measuring triglyceride and nonesterified fatty acid (NEFA) concentrations in hyperinsulinemic (HI) and insulin-resistant (IR) horses. ANIMALS: Twenty horses including 7 HI-IR horses, 4 HI-non-IR horses, and 9 non-HI-non-IR horses (control). METHODS: Cross-sectional design. Horses underwent an OGT, with blood samples collected at 0, 60, 90, and 120&#x2009;minutes. Insulin, glucose, triglyceride, and NEFA concentrations were measured and compared over time and between groups, with P&#x2009;<&#x2009;.05 considered significant. RESULTS: In all horses, the OGT had a significant effect on triglyceride concentrations (median [interquartile range]: .35 [.30-.50] mmol/L at 0&#x2009;minute vs .25 [.21-.37] mmol/L at 120&#x2009;minutes, P&#x2009;=&#x2009;.005) and on NEFA concentrations (.1 [.1-.2] mEq/L at 0&#x2009;minute vs .05 [.05-.1] mEq/L at 120&#x2009;minutes, P&#x2009;=&#x2009;.0009). However, horses with HI and IR had higher triglyceride areas under the curve (AUC, 79.46&#x2009;&#xb1;&#x2009;46.59 vs 33.32&#x2009;&#xb1;&#x2009;6.75&#x2009;mmol/L*min, P&#x2009;=&#x2009;.01) as well as NEFA AUC (9.1&#x2009;&#xb1;&#x2009;2.9 vs 6.0&#x2009;&#xb1;&#x2009;6.8&#x2009;mEq/L*min, P&#x2009;=&#x2009;.03) than control horses. No significant difference was detected between control and HI non-IR horses. CONCLUSIONS AND CLINICAL IMPORTANCE: Determining triglyceride and NEFA concentrations might help assess tissue insulin resistance during an OGT.