Insulin dysregulation (ID) is a prevalent metabolic disorder in horses, particularly in those with equine metabolic syndrome, and represents a principal risk factor for endocrinopathic laminitis. ID arises from a combination of insulin resistance, exaggerated pancreatic insulin secretion, and impaired hepatic insulin clearance, with obesity, high intake of nonstructural carbohydrates, physical inactivity, and chronic low-grade inflammation acting as key drivers. Mechanistically, defects in postreceptor insulin signaling, innate immune activation, oxidative stress, and endothelial dysfunction contribute to reduced insulin responsiveness and promote compensatory hyperinsulinemia, which can occur despite only mild hyperglycemia. Sustained hyperinsulinemia and associated metabolic stress are implicated in vascular and tissue changes within the digital laminae, facilitating laminitis development. This manuscript summarizes contemporary concepts of ID pathophysiology and outlines practical diagnostic strategies, emphasizing the strengths and limitations of basal insulin measurements and fasting-derived proxy indices, and highlighting dynamic testing approaches for detecting postprandial hyperinsulinemia in clinical settings. Early recognition and targeted management through dietary modification, weight reduction, structured exercise, and selected pharmacologic interventions are essential to mitigate laminitis risk and improve long-term outcomes.