Use of the oral sugar test in ponies when performed with or without prior fasting.
Abstract: It is recommended that the oral sugar test (OST) for insulin dysregulation (ID) be performed after an overnight fast, but fasting is impractical in ponies kept solely at pasture. There are few data on OST repeatability and reliability in ponies. Objective: To report 1) whether OST results obtained in the morning after an overnight fast or without fasting in the afternoon (FASTING/FED) can be used interchangeably, 2) time of highest insulin concentration T [insulin], repeatability and reliability of insulin response to the OST when FASTING or FED and 3) dichotomous agreement (ID/normal) within a small sample when FASTING or FED. Methods: Method comparison study. Methods: Oral sugar tests were performed on four occasions in 10 adult native British ponies, twice FASTING and twice FED. Insulin concentrations were measured by radioimmunoassay at 0-120 min (T ). Differences between FASTING and FED results were assessed using mixed effects models. Indices of repeatability and reliability were calculated; dichotomous agreement was reported using kappa statistics. Results: Serum [insulin] was significantly (P≤0.05) higher at T -T with prior fasting (estimated differences [95% confidence intervals]): T : 23.5 μiu/ml (8.7-38.4 μiu/ml), T : 27.1 μiu/ml (12.3-41.8 μiu/ml), T : 15.1 (0.36-29.9 μiu/ml). Most frequently, T [ins] occurred at T . At any single time point, within-subject coefficients of variation were: FASTING: 40% and FED: 31%. The 95% limits for repeatability were FASTING: 29-340%, FED: 41-240%. Test reliabilities were FASTING: 0.70 and FED: 0.67. For dichotomous interpretation similar results (kappa = 0.7) were obtained using cut-offs of [Insulin] >60 μiu/ml at T or T for FASTING and [Insulin] >51 μiu/ml at T or T for FED samples. Conclusions: Oral sugar tests were performed on a small number of animals on one pasture during one season (spring). Conclusions: Clinicians should beware of interpreting changes in absolute OST results owing to poor repeatability. When stabling is unavailable, OSTs of ponies at pasture may yield similar dichotomous results without prior fasting.
© 2016 EVJ Ltd.
Publication Date: 2016-09-05 PubMed ID: 27381044DOI: 10.1111/evj.12607Google Scholar: Lookup
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- Journal Article
Summary
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The research is centered around a study that tested the reliability of oral sugar test (OST) for detecting insulin dysregulation in ponies, comparing the results obtained from a fasting pony and a non-fasting one.
Test Procedure
- The study conducted four OSTs on 10 adult native British ponies.
- Two of these tests were carried out when the ponies were fasting and two were done on fed ponies.
Findings
- Insulin levels were significantly higher when ponies were tested after fasting.
- The highest occurrence of insulin concentration was found on the fasting samples.
- However, the reliability of the test results showed minimal difference whether the ponies were fasted or fed during testing. The reliability of the tests was 0.70 for fasting ponies and 0.67 for fed ponies.
- In terms of dichotomous interpretation (distinguishing between normal insulin levels and insulin dysregulation), similar results were found for both fasting and fed ponies.
Limitations and Implications
- The study was conducted on a small sample size, and all animals were kept on the same pasture during a single season (spring). This may limit the generalizability of the findings.
- Despite these limitations, the study suggests that when stable conditions are unavailable, performing an OST on ponies at pasture without prior fasting could yield similar discriminative results.
Conclusion
- According to the research findings, clinicians dealing with ponies should be cautious when interpreting changes in OST results due to its poor repeatability.
- However, if stabling is not possible, OSTs can be performed on ponies without fasting with a similar discriminative outcome.
Cite This Article
APA
Knowles EJ, Harris PA, Elliott J, Menzies-Gow NJ.
(2016).
Use of the oral sugar test in ponies when performed with or without prior fasting.
Equine Vet J, 49(4), 519-524.
https://doi.org/10.1111/evj.12607 Publication
Researcher Affiliations
- Department of Clinical Sciences and Services, Royal Veterinary College, London, UK.
- Bell Equine Veterinary Clinic, Mereworth, Kent, UK.
- Equine Studies Group, WALTHAM Centre for Pet Nutrition, Waltham on the Wolds, Leicestershire, UK.
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, UK.
- Department of Clinical Sciences and Services, Royal Veterinary College, London, UK.
MeSH Terms
- Animals
- Blood Glucose / metabolism
- Fasting / metabolism
- Glucose Tolerance Test / methods
- Glucose Tolerance Test / veterinary
- Horses / metabolism
- Hyperinsulinism
- Insulin / metabolism
- Reproducibility of Results
- Seasons
Citations
This article has been cited 17 times.- Go YY, Hazard NW, Balasuriya UBR, Chapman AM, Fitton NS, Kenéz Á, Andrews FM. Clinical evaluation of the Immulite® 1000 chemiluminescent immunoassay for measurement of equine serum insulin. Front Vet Sci 2023;10:1018230.
- Warnken T, Schaub C, Delarocque J, Frers F, Feige K, Sonntag J, Reiche DB. Palatability, glycemic, and insulinemic responses to various carbohydrate formulations: Alternatives for the diagnosis of insulin dysregulation in horses?. J Vet Intern Med 2023 Jan;37(1):282-291.
- de Laat MA, Warnken T, Delarocque J, Reiche DB, Grob AJ, Feige K, Carslake HB, Durham AE, Sillence MN, Thane KE, Frank N, Brojer J, Lindase S, Sonntag J. Carbohydrate pellets to assess insulin dysregulation in horses. J Vet Intern Med 2023 Jan;37(1):302-314.
- Stefanovski D, Robinson MA, Van Eps A. Effect of a GLP-1 mimetic on the insulin response to oral sugar testing in horses. BMC Vet Res 2022 Jul 29;18(1):294.
- Timko KJ, Hostnik LD, Watts MR, Chen C, Bercz A, Toribio RE, Belknap JK, Burns TA. Diagnostic evaluation of insulin and glucose dynamics in light-breed horses receiving dexamethasone. Can Vet J 2022 Jun;63(6):617-626.
- Karikoski NP, Box JR, Mykkänen AK, Kotiranta VV, Raekallio MR. Variation in insulin response to oral sugar test in a cohort of horses throughout the year and evaluation of risk factors for insulin dysregulation. Equine Vet J 2022 Sep;54(5):905-913.
- Dunkel B, Knowles EJ, Chang YM, Menzies-Gow NJ. Influence of endocrine disease on l-lactate concentrations in blood of ponies. J Vet Intern Med 2021 May;35(3):1582-1588.
- Box JR, McGowan CM, Raekallio MR, Mykkänen AK, Carslake H, Karikoski NP. Insulin dysregulation in a population of Finnhorses and associated phenotypic markers of obesity. J Vet Intern Med 2020 Jul;34(4):1599-1605.
- Hodge E, Kowalski A, Torcivia C, Lindborg S, Stefanovski D, Hart K, Frank N, van Eps A. Effect of thyrotropin-releasing hormone stimulation testing on the oral sugar test in horses when performed as a combined protocol. J Vet Intern Med 2019 Sep;33(5):2272-2279.
- Moser K, Banse H. Comparison of the glucose and insulin responses of horses to 2 formulations of corn syrup. Can Vet J 2019 Jun;60(6):637-643.
- de Laat MA, Reiche DB, Sillence MN, McGree JM. Incidence and risk factors for recurrence of endocrinopathic laminitis in horses. J Vet Intern Med 2019 May;33(3):1473-1482.
- Durham AE, Frank N, McGowan CM, Menzies-Gow NJ, Roelfsema E, Vervuert I, Feige K, Fey K. ECEIM consensus statement on equine metabolic syndrome. J Vet Intern Med 2019 Mar;33(2):335-349.
- de Laat MA, Sillence MN, Reiche DB. Phenotypic, hormonal, and clinical characteristics of equine endocrinopathic laminitis. J Vet Intern Med 2019 May;33(3):1456-1463.
- Frank N, Walsh DM. Repeatability of Oral Sugar Test Results, Glucagon-Like Peptide-1 Measurements, and Serum High-Molecular-Weight Adiponectin Concentrations in Horses. J Vet Intern Med 2017 Jul;31(4):1178-1187.
- Al-Ansari AS, Duggan V, Mulcahy G, Yin X, Brennan L, Cotter PD, Patel SH, O'Donovan CM, Crispie F, Walshe N. Faecal microbiota and serum metabolome association with equine metabolic syndrome in connemara ponies. BMC Vet Res 2025 Jul 1;21(1):411.
- Barnabé MA, Elliott J, Harris PA, Menzies-Gow NJ. Effects of pasture consumption and obesity on insulin dysregulation and adiponectin concentrations in UK native-breed ponies. Equine Vet J 2026 Jan;58(1):243-255.
- Thane K, Sonntag J, Warnken T, Reiche D, Uricchio C, Frank N. Comparison of a customized glycemic pellets challenge with the oral sugar test to measure glycemic and insulinemic responses in horses. J Vet Intern Med 2024 Nov-Dec;38(6):3281-3287.
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