Equine Insulin Converter


Pituitary pars intermedia dysfunction (PPID; also called equine Cushing syndrome) and the equine metabolic syndrome (EMS) are associated with an increased risk for laminitis mediated by insulin dysregulation. To detect insulin dysregulation, it is necessary to measure blood insulin concentrations in the fasted horse or pony, or during more sensitive test protocols. However, the assays available to measure insulin in horses and ponies provide discordant results. This Web App provides means to compare insulin values obtained with certain assays to reference ranges and cut-offs established using other assays, or simply to convert blood insulin concentrations from one assay to another.
Pairs of assays which can currently be compared.
Fig. 1 — Pairs of assays for which a comparison is possible.

This web app encapsulates the relationship between pairs of assays we and our partners came to compare with each other over the years. An assay-specific insulin measurement can be converted to an approximate value of what would have been obtained with other assays using polynomials. We currently provide conversion for the assay pairs presented in figure 1.

To use the app, enter an insulin measurement obtained with one of the available assays (in µIU/mL) and press enter or click the ‘convert’ button. Please bear in mind that the conversion adds additional uncertainty to the measurement and that every medical decision should take the clinical circumstances into account.


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More information

As demonstrated in figure 2, insulin cut-offs are not applicable as-is, independently of the assay used, warranting the use of assay-specific reference ranges or, in their absence, approximate solutions such as our conversion app.

Comparison of different published cut-offs across assays.
Fig. 2 — Comparison of different published cut-offs across assays.
1. Warnken T, Delarocque J, Schumacher S, Huber K, Feige K. Retrospective analysis of insulin responses to standard dosed oral glucose tests (OGTs) via naso-gastric tubing towards definition of an objective cut-off value. Acta Veterinaria Scandinavica 2018;60. doi:10.1186/s13028-018-0358-8.
2. de Laat MA, Warnken T, Delarocque J, Reiche DB, Grob AJ, Feige K, et al. Carbohydrate pellets to assess insulin dysregulation in horses. Veterinary Internal Medicne 2022;37:302–14. doi:10.1111/jvim.16621.
3. Equine Endocrinology Group, Recommendations for the Diagnosis and Treatment of Equine Metabolic Syndrome (EMS), 2020, accessed August 2021.
4. Carter RA, Treiber KH, Geor RJ, Douglass L, Harris PA. Prediction of incipient pasture‐associated laminitis from hyperinsulinaemia, hyperleptinaemia and generalised and localised obesity in a cohort of ponies. Equine Veterinary Journal 2009;41:171–8. doi:10.2746/042516408x342975.
5. Lindåse S, Nostell K, Bergsten P, Forslund A, Bröjer J. Evaluation of fasting plasma insulin and proxy measurements to assess insulin sensitivity in horses. BMC Vet Res 2021;17. doi:10.1186/s12917-021-02781-5.

The conversion of insulin measurements is not strictly proportional to an assay-specific coefficient. The interaction between assays and insulin ought to be investigated using recombinant equine insulin or standardised pooled samples available to all laboratories.

A paper describing the exact methodology to obtain the conversion functions was recently published. Briefly, monotonically non-decreasing splines were fitted with non-negative least-squares regression to describe the relationship between assay pairs, as derived from samples where insulin was measured with two or more assays concurrently. Each function was visually inspected to preclude overfitting. The obtained functions were transformed to polynomials and embedded in the present app. The intervals given on the right hand side before any conversion are the ranges for which data is available in the app. After conversion, prediction intervals are given instead. They describe the uncertainty around the conversion which depends on the amount of available data and concordance of the assay pairs.

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All the information on this website is published in good faith and for general information purpose only. We do not make any warranties about the completeness, reliability and accuracy of this information. The results provided by the conversion module may change in future versions at the sole discretion of the authors. Any action you take upon the information you find on this website, is strictly at your own risk.

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