From pasture to pancreas: understanding glycemic and insulin regulation in hindgut fermenter health and disease

Citation

Macon EL. 2025. From pasture to pancreas: understanding glycemic and insulin regulation in hindgut fermenter health and disease. In Treiber K, Brooks M, D’amato-Anderson J, Nylander J, Eds. Proceedings of the Sixteenth Conference on Zoo and Wildlife Nutrition, AZA Nutrition Advisory Group, Oklahoma City, OK.

Abstract

Modern equine management and nutrition often expose horses to higher levels of starch and simple sugars than those found in a natural grazing environment. In hindgut fermenters such as horses, excess starch can overwhelm small intestinal digestion, producing exaggerated insulin responses and allowing undigested starch to enter the hindgut where it disrupts microbial fermentation. Over time, modern management, including stall confinement and meal feeding, and over nutrition can reduce insulin sensitivity and promote insulin dysregulation (ID), a collective term for tissue insulin resistance and hyperinsulinemia. Insulin is central to regulating blood glucose and coordinating nutrient use, and when its regulation is impaired, the consequences for metabolic health and welfare can be significant. Systemic glycemia in hindgut fermenters is generally well maintained through insulin-dependent glucose uptake by tissues, hepatic glucose handling, and the coordinated actions of hormones such as insulin, catecholamines, cortisol, and incretins. In horses, however, the hallmark disturbance is not hyperglycemia but exaggerated or prolonged insulin secretion. The major endocrine disorders of the horse, including Equine Metabolic Syndrome (EMS), Pituitary Pars Intermedia Dysfunction (PPID), and ID, are characterized by this abnormal insulin response, and the resulting complications, most notably laminitis, may be mitigated through evidence-based interventions and nutritional management strategies that specifically target hyperinsulinemia to support long-term metabolic health and welfare.

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