Testing for Insulin Dysregulation

Insulin dysregulation (ID), which includes insulin resistance and abnormally high levels of insulin in the blood (hyperinsulinemia), is a known cause of endocrine-associated laminitis, as well as an underlying cause of equine metabolic syndrome that leads to obesity often characterized by fat pads and cresty necks. Testing for these conditions remains a challenge, so researchers from the Universities of Queensland and Melbourne examined the relative utility of three diagnostic tests for diagnosing ID and identifying horses with underlying laminitis.

A total of 146 healthy Welsh and Shetland ponies were recruited into the study, tested for ID using three different blood tests (baseline insulin levels, insulin levels after an oral dose of sugar and an insulin resistance test that involves measuring sugar levels after injecting a dose of insulin). The ponies were also examined for the presence of laminitis. The testing identified 79 of the 146 ponies as affected by ID. Used individually, none of the three tests identified every case of ID. Baseline insulin testing alone missed 86% (68/79) of the cases, the oral sugar test missed 43% (34/79) and the insulin resistance test missed 14% (11/79). While a pony with a high baseline insulin level would likely have ID, a normal insulin level would not necessarily rule out ID. Only running both the oral sugar test and the insulin resistance test together has a high probability of identifying every case.

—Clark BL et al. The Vet J 2023;106019

A Feed Supplement to Lower Insulin Levels

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