Postprandial insulin responses to various feedstuffs differ in insulin dysregulated horses compared with non-insulin dysregulated controls.
Authors: Macon Erica L, Harris Patricia, Bailey Simon, Barker Virginia D, Adams Amanda
Journal: Equine veterinary journal
Summary
# Postprandial Insulin Responses to Feedstuffs in Insulin Dysregulated Horses Controlling excessive insulin spikes after feeding is crucial for managing insulin dysregulated (ID) horses, as hyperinsulinaemia significantly increases laminitis risk. This 2022 research compared postprandial insulin responses between eight to eleven ID horses and control animals across two feeding trials, using feedstuffs with markedly different nonstructural carbohydrate (NSC) and crude protein profiles—ranging from high-NSC grains like cracked corn (74% NSC) to low-NSC pellets (6% NSC). ID horses demonstrated dramatically exaggerated insulin responses to all diets, with area-under-curve insulin values reaching 22,362 µIU/mL/min compared to just 6,145 µIU/mL/min in non-dysregulated controls, and notably, the high-NSC cracked corn triggered 32% higher insulin responses than ration balancers in ID animals. Most significantly, 60-minute post-feeding insulin concentrations for the low-NSC pellet (57.8 µIU/mL) were substantially lower than all other feeds tested in ID horses, though NSC content rather than protein appeared to be the primary driver of the insulin spike. For practitioners managing ID horses, these findings reinforce that NSC restriction remains the cornerstone of dietary intervention, but equally important is recognising that individual ID animals cannot tolerate dietary NSC thresholds based on their non-dysregulated counterparts—even moderate-NSC feeds warrant careful monitoring in susceptible animals.
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Practical Takeaways
- •ID horses respond disproportionately to even small amounts of NSC-containing feeds; feeding low-NSC pellets (<6% NSC) significantly reduces dangerous postprandial insulin spikes and laminitis risk
- •High-protein or balanced ration formulations do not meaningfully reduce insulin responses in ID horses compared to high-NSC grains—NSC content must be the primary selection criterion
- •Dietary guidelines for managing ID horses cannot be safely based on responses in healthy horses; ID horses require individualized feeding strategies focused on NSC minimization
Key Findings
- •Insulin dysregulated (ID) horses had significantly greater postprandial insulin responses (AUCi 22,362 µIU/mL/min) compared to non-insulin dysregulated controls (6,145 µIU/mL/min) across all diets (P < 0.001)
- •In ID horses, cracked corn (74% NSC) produced higher insulin response (32,000 µIU/mL/min) than ration balancer with low protein (18,977 µIU/mL/min; P = 0.01), while diet had no effect on non-dysregulated horses (P = 0.2)
- •Low NSC pellet resulted in significantly lower 60-minute insulin levels in ID horses (57.8 µIU/mL) compared to all other diets (160.1 µIU/mL; P < 0.02)
- •Nonstructural carbohydrate (NSC) is the primary driver of postprandial insulin response, and dietary threshold recommendations cannot be extrapolated from non-dysregulated to dysregulated horses