Insulin sensitivity and glucose dynamics in neonatal foals

Abstract

Metabolic programming during fetal and neonatal growth may predispose development of insulin resistance, which is associated with obesity and laminitis in mature horses. This study examined insulin and glucose dynamics in neonatal foals and the influence of maternal diet on neonatal insulin sensitivity. Twenty-two late gestation mares maintained on pasture were supplemented 67% of energy requirements with feed high in either soluble carbohydrates or fat and fiber. Foals were born spontaneously and an intravenous glucose tolerance test applied at 5 ± 1 d of age. Insulin sensitivity (SI) and insulin independent glucose clearance (Sg) were determined by the minimal model of insulin and glucose dynamics. Foals exhibited high SI and Sg, relative to mature horses, indicating a large capacity for glucose uptake with or without insulin. Insulin sensitivity (median 26.1 ×104 mIU−1·L·min−1) ranged widely (4.0 – 67.1) and was substantially higher than values for mature horses (median 1.8; 95% reference interval 0.2 – 5.9). Variation in SI was not attributable to maternal dietary treatments, sex, age, birthweight, or mare SI (measured in late gestation). The neonate clearly demonstrates higher insulin dependent and independent glucose clearance than mature horses, but factors affecting variation in these parameters remain unclear. Research supported by the late Paul Mellon and the WALTHAM Centre for Pet Nutrition