EFFECTS OF EXOGENOUS INSULIN ON PROTEIN METABOLISM IN EXTREMELY LBW INFANTS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Hyperglycemia in the first days of life is common in ELBW infants. It has been reported to have an incidence of approximately 5% in all infants admitted to the NICU, and to occur 18 times more commonly in infants <1000g compared to those >2000g. In ELBW infants, hyperglycemia can occur even on minimal glucose intakes. In this situation, many centers administer insulin to avoid osmotic diuresis, possible undesirable CNS effects of hyperglycemia, and the need to deliver hyposmolar solutions to control hyperglycemia. In these settings, insulin is effective in reducing hyperglycemia. Since this hyperglycemia in the immediate newborn period is usually a transient event lasting 2-5 days, the use of insulin in this setting is primarily focused on fluid and electrolyte management and not on advancing nutritional support. However, insulin's effect on protein metabolism is not well understood in this population, and the only study investigating amino acid kinetics suggests no anabolic effect but a marked increase in lactate concentration with insulin use. Given the widespread use of insulin in the management of ELBW infants, we feel it is prudent to further delineate insulin's effects as used in current clinical practice. We propose to use stable isotope methodology to investigate the effect of insulin on glucose and amino acid metabolism and lactate production in ELBW neonates in insulin-resistant early-onset neonatal hyperglycemia.