The primary objective of this study is to characterize patterns of growth parameters in young growing Thoroughbred foals (0 to 15 months) and to examine associations between those growth patterns and basal plasma glucose, insulin and non-esterified fatty acids concentration. Monthly blood samples and measurements of weight, wither height, girth, and forearm length were obtained for two groups of foals, over two respective years (May 2003 – June 2004 & May 2005 – July 2006). The foals had access to fresh forage, and were provided with concentrates of different energy sources twice daily. Plasma concentrations of glucose, insulin and NEFA concentrations were quantified. Glucose and insulin concentrations were positively correlated with rates of daily gain in weight, height, girth, and forearm length (P < 0.0001). NEFA was negatively correlated with weight (P < 0.0001) and girth daily gain (P < 0.05). This study documents patterns of essential metabolites and their primary regulatory hormone, which could serve as a reference for caring for young growing foals. These patterns have not been previously reported, and such data is valuable to understanding and optimizing equine health. By understanding growth and metabolic changes in foals, a diet may be precisely tailored to control growth, and lower incidence of skeletal disease. This data may also be useful in clinical practice for assessment of healthy foals throughout their development.