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Ontogeny of glucose homeostasis in low birth weight infants
R M Cowett1, G E Andersen, C A Maguire
1Department of Pediatrics, Women and Infants Hospital of Rhode Island, Providence 02905-2401.
Insights
Glucose homeostasis in neonates remains transitional for weeks after birth. Low birth weight infants show persistent endogenous glucose production (Ra) during glucose infusion, indicating delayed maturation of metabolic control.
Area of Science:
- Neonatology
- Endocrinology
- Metabolic Regulation
Background:
- Adults suppress endogenous glucose production (Ra) when infused with glucose.
- Neonate glucose metabolism differs, showing persistent Ra, indicating a transitional homeostatic state.
- Postnatal development's impact on neonatal glucose regulation requires further investigation.
Purpose of the Study:
- To assess if low birth weight infants develop adult-like glucose production suppression after birth.
- To investigate the persistence of endogenous glucose production (Ra) in infants aged 2-5 weeks during glucose infusion.
Main Methods:
- Measured endogenous glucose production rate (Ra) using D-(U-13C)glucose tracer infusion.
- Infused glucose (5.3 mg.kg-1min-1) or saline in paired studies on 11 infants (gestational age 33 weeks).
- Analyzed plasma glucose and insulin concentrations during infusion periods.
Main Results:
- Plasma glucose increased significantly (88 to 101 mg/dL) during glucose infusion (P < 0.001).
- Plasma insulin levels remained unchanged.
- Persistent Ra was observed in 6 of 11 infants, indicating incomplete metabolic adaptation.
Conclusions:
- Glucose homeostasis in low birth weight infants is transitional for several weeks postnatally.
- Infants aged 2-5 weeks may not exhibit complete suppression of endogenous glucose production during glucose infusion.
- Delayed maturation of glucose regulatory mechanisms persists beyond the immediate neonatal period.
Abstract:
Suppression of the endogenous glucose production rate (Ra) is the adult response to glucose infusion. Persistent Ra (greater than or equal to 1 mg.kg-1min-1 or less than 80% decrease in basal Ra) in response to glucose infusion is evidence of a transitional homeostatic state in the neonate during the first days after birth. To determine whether postnatal development produces an adultlike response, Ra was measured in 11 infants (birth weight 1716 +/- 48 g, gestational age 33 +/- 0.3 weeks) at 2 to 5 weeks of age. In these paired studies, 4 micrograms.kg-1min-1 D-(U-13C)glucose tracer was infused by prime constant infusion to determine Ra, during infusion of either saline solution or glucose, the latter at a rate of 5.3 +/- 0.2 mg.kg-1min-1 (mean +/- SEM). When the results of the saline infusion turnover period were compared with those of the glucose infusion turnover period, plasma glucose concentration increased significantly, from 88 +/- 3 mg/dL to 101 +/- 4 mg/dL (P less than 0.001). Plasma insulin concentration remained unchanged (12 +/- 5 microU/mL vs 8 +/- 3 microU/mL). Ra was heterogenous during glucose infusion, and persistent Ra was present in six of 11 infants. Of the five infants who had decreased Ra during glucose infusion, three received glucose at a rate exceeding basal Ra. Of the remaining six infants who evidenced persistent Ra during glucose infusion, three received glucose at a rate equal to or in excess of basal Ra. We conclude that glucose homeostasis in low birth weight infants is transitional throughout the neonatal period.