Maturation of insulin and glucose responses to normal feeding in foals.

Postprandial insulin and glucose concentrations were measured in 3 Arabian and 3 Thoroughbred foals at 1 day, 1 week, 1 month and 3 months of age. Prefeeding serum insulin concentrations were similar in foals at 1 day (25.9 +/- 5.1 pmol/L), 1 week (32.4 +/- 5.8 pmol/L), and 1 month (38.2 +/- 7.9 pmol/L), but had increased significantly to 131.0 +/- 20.2 pmol/L at 3 months of age (P < 0.05). There was significantly increased serum insulin secretion after a feed in foals at 3 months of age (P < 0.05) when compared with that at younger ages. Prefeeding serum glucose concentrations ranged from 6.0 +/- 0.7 mmol/L at 1 day, to 5.9 +/- 0.9 mmol/L at 1 week, 4.9 +/- 1.7 mmol/L at 1 month, and 4.4 +/- 1.5 mmol/L at 3 months of age. There were lower postprandial glucose concentrations with advancing age. It appeared that there was a period of maturation in pancreatic beta-cell function after birth in foals, which reached adult levels by 3 months of age.