Insulin-secreting capacity in newborn infants.

The normal adult and older children exhibit an immediate insulin secretory response with peak insulin levels being reached within 5-10 minutes after a rapid intravenous glucose injection. It has been shown that the newborn disposes of glucose slowly,1,2 and that plasma insulin response to intravenous glucose injec tion is significantly delayed in newborn infants 3-5 Isles et al demonstrated that a very high insulin level is reached in the umbilical vein approximately 60 minutes following a rapid intravenous glucose injection and that there is a rapid change in plasma insulin values from one specimen to the next during the intravenous glucose tolerance test in normal newborn infants.6 Their findings may provide a basis for the divergent inter pretation of insulin secreting capacity of the normal newborn infants without the knowledge of the neonatal vascular anatomy. In newborn infants the umbilical vein has been used as a source of blood sampling, as it is readily available for repeated blood sampling. The umbilical vein receives blood supply from the portal vein directly