Glucose homeostasis in the newborn. Effects of oral feeding on response to fasting and intravenous glucose infusion in neonatal piglets.

The effect of oral feeding on the response to fasting and to an intravenous glucose infusion was investigated in neonatal piglets. Piglets, which had received no food at birth, reduced both their rates of glucose appearance and glucose utilisation (at 24 h: 43 +/- 3.5 mumol/min in previously fed piglets and 28 +/- 6 mumol/min in fasted piglets; at 48 h: 45 +/- 3.5 mumol/min in previously fed piglets and 25 +/- 5 mumol/min in fasted piglets). This reduction in glucose turnover was not associated with a fall in plasma glucose concentration, and all groups of piglets were normoglycaemic at the start of the study. An intravenous infusion of glucose (100 mumol/kg/min) resulted in suppression of hepatic glucose output and an increase in the glucose utilisation rate. Piglets, which had received no food at birth, had lower absolute rates of glucose utilisation throughout the period of infusion. The present study indicates that major changes in glucose turnover rates may occur prior to these being reflected in changes in blood glucose concentration. The results also indicate that oral feeding affects both steady-state glucose turnover and the response to an intravenous glucose infusion.