Managing insulin dysregulation in horses: a role for nutraceuticals

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Insulin resistance (IR) and insulin dysregulation (ID) in horses are major risk factors for developing laminitis; a painful and potentially debilitating condition. While some horses are genetically predisposed to IR, diet also plays a critical role in its development. Because of this, there's growing interest in whether specific dietary strategies, including the use of nutraceuticals, can help reduce the risk.

A recent study led by Caroline Loos and her colleagues at the University of Kentucky's Gluck Equine Research Center, and published in the journal Animals,  explored whether supplementing the diet with a specific combination of nutrients could help improve insulin regulation in horses that are prone to IR. 

The trial involved 16 mature horses with a known history of insulin dysregulation. The horses were split into two groups:

• One group received a nutraceutical supplement containing omega-3 fatty acids, glutamine, vitamin E, and active yeast.
• The other group received a placebo.

Both supplements were given once daily for four weeks. During the study, horses were kept on dry lots, had free access to grass hay, and were also fed a grain concentrate twice daily (providing 0.5 g of starch per kg of body weight per meal).

To assess the horses’ insulin regulation, each underwent a Combined Glucose–Insulin Tolerance Test (CGIT) at the start and end of the trial. The CGIT is a diagnostic test commonly used in equine medicine to evaluate how effectively a horse’s body clears glucose from the bloodstream in response to insulin. During the test, horses receive a bolus (injection) of glucose and insulin, and blood samples are collected over a 150-minute period to track how quickly glucose and insulin levels return to baseline. The faster the return to normal, the better the horse’s insulin sensitivity.

After four weeks of supplementation, horses receiving the nutraceutical showed notable improvements:

• 61% faster glucose clearance compared to the placebo group.
• Shorter time for blood glucose levels to return to normal.
• Lower insulin levels at 75 minutes post-test, indicating reduced hyperinsulinemia.
• Glucose concentrations were also lower at 45 minutes post-test in the supplemented group.

In contrast, horses in the placebo group still had elevated insulin levels 150 minutes after the test, suggesting poorer insulin regulation.

These findings suggest that prophylactic use of specific nutraceuticals may help improve insulin sensitivity and reduce the risk of insulin-associated laminitis, particularly in horses consuming high-starch diets. By supporting faster glucose clearance and lowering insulin levels, this approach may offer a valuable management tool for horses at risk of ID or IR.

While more research is needed to confirm long-term benefits, this study highlights the potential of targeted dietary supplementation in supporting metabolic health in horses.

 

For more details, see:

 

Loos, Caroline, Annette Castelein, Eric Vanzant, Emma Adam, and Kyle R. McLeod. 

Nutraceutical Supplement Mitigates Insulin Resistance in Horses with a History of Insulin Dysregulation During a Challenge with a High-Starch Diet

Animals (2024) 14, no. 23: 3385. 

https://doi.org/10.3390/ani14233385