Glucose disappearance rate, insulin response and growth hormone response in the small for gestational age and premature infant of very low birth weight.

The purpose of the present investigation was to study the disappearance rate of intravenously administered glucose, plasma insulin, plasma growth hormone (GH) and their responses to an intravenous glucose load in 29 infants who were small for gestational age (SGA). The findings were compared to those in 19 premature babies of similar birth weight who were appropriate for gestational age (AGA); in all the weights were below 2,000 g. The babies were divided in two groups according to their age when tested, at less than 24 and 25-48 h. SGA infants cleared glucose more rapidly than AGA infants (p less than 0.01) whose clearance rates were similar to those previously reported in normal full-size and full-term newborns. Arterial insulin values before glucose loading were similar in all groups. The insulin response to glucose was poor in both SGA and AGA infants, but there was no significant difference between these two groups of infants. The response in the two groups at 24 and 25-48 h was similar. In 8 SGA babies insulin response was studied shortly after glucose injection to determine beta-cell release, but there was no significant difference of insulin level before and after glucose administration. In 5 AGA and 8 SGA babies insulin response was studied simultaneously in portal vein and aorta. In AGA babies the insulin response was completely different in the two vessels with a high response in the vein; on the contrary, in SGA infants response was variable. Growth hormone levels were high before test in SGA and AGA; after a glucose load the plasma GH levels increase, but the response was identical in SGA and AGA.