Glucose intolerance and insulin resistance in extremely premature newborns, and implications for nutritional management

Risk factors for hyperglycemia in extremely low birth weight infants during the first 14 days

BACKGROUND

There are limited data regarding the risk factors for hyperglycemia in extremely low birth weight infants (ELBWIs). The aim of this observational study was to investigate the incidence of hyperglycemia among ELBWIs during the first 14 days of life and identify independent risk factors for hyperglycemia development.

METHODS

We retrospectively evaluated 55 ELBWIs (32 male infants) between January 2015 and March 2020. Hyperglycemia was diagnosed when the glucose level was ≥180 mg/dL. Demographic and clinical data were extracted from the patients' medical records. The risk factors associated with the onset of hyperglycemia were identified by Cox proportional hazards regression analysis with variables that had previously been identified as risk factors for hyperglycemia.

RESULTS

Hyperglycemia developed in 23 patients (41.8%) within the first 14 days of life. Gestational age, chorioamnionitis, postnatal intravenous glucocorticoids, and probiotic type were included in the analysis. The results indicated that hyperglycemia was significantly associated with gestational age (hazard ratio [HR], 0.65; 95% confidence interval [CI], 0.48-0.87; P = 0.004). Further, Bifidobacterium breve (B. breve M-16V) use was related to hyperglycemia in ELBWIs (HR, 2.95; 95% CI, 1.10-7.87; P = 0.031).

CONCLUSION

Hyperglycemia was strongly associated with lower gestational age and B. breve M-16V use in our study population. Although probiotic supplementation may be beneficial for preterm infants to reduce the incidence of necrotizing enterocolitis, the dextrin used as an excipient in B. breve M-16V may lead to an undesirable carbohydrate load in ELBWIs.

[Does early parenteral protein intake improve extrauterine growth in low birth weight preterms?]

INTRODUCTION

Extrauterine growth restriction affects most premature newborns. Early and higher parenteral protein intake seems to improve postnatal growth and associated comorbidities. We evaluate the impact of a new parenteral nutrition protocol based on early amino acid administration on postnatal growth in premature infants with a birth weight < 1,500 grams.

MATERIAL AND METHODS

A case-control study in 58 premature newborns with a birth weight < 1,500 grams. In the case group we included 29 preterm neonates who received at least 1.5 g/kg/day parenteral amino acid during the first 24 hours after birth, reaching a maximum dose of 3.5 g/kg/day on the 3(rd)-4(th) day after birth. The control group was formed by 29 preterm neonates for whom protein support began on the 2(nd-)3(rd) day after birth with a dose of 1g/kg/day with lower daily increases than the case group. Growth rates and complications were followed until 28 days of life or discharge from NICU.

RESULTS

There were no differences between groups in baseline characteristics. Premature newborns who received higher and earlier doses of proteins had a greater weight gain than the control group, and this difference was statistically significant (423 ± 138 g vs. 315 ± 142 g; P=.005). In addition, they had a higher daily weight gain rate (19.4 ± 3.3 vs. 16.5 ± 4.8; P=.010) and they regained birth weight earlier (11.5 ± 3.3 days vs. 14.5 ± 4.5 days; P=.045). A higher incidence of complications was not observed.

CONCLUSIONS

Early and higher amino acid administration improves growth rate in premature neonates with no apparent increase in risks for the patient.

Early postnatal nutrition and programming of the preterm neonate

Early postnatal nutrition is a vital determinant of adult health; this is particularly true for the infant born prematurely and cared for in a hospital setting such as the neonatal intensive care unit. Human and animal studies support the contribution of postnatal dietary composition and the rate of extrauterine growth to long-term metabolic outcomes. One mechanism by which postnatal nutrition affects long-term outcome is via developmental programming. Programming, or the modulation of gene expression to impart a short-term advantage accompanied by a long-term cost, may be achieved by epigenetic modifications to chromatin. This review summarizes the details of postnatal nutritional content and rate of growth on the development of metabolic disease. The role of epigenetics in developmental programming of the preterm infant is also discussed, with an emphasis on animal models of dietary manipulation and directions in which the field must move in order to formulate effective feeding strategies for the preterm infant.

[Ontogenesis of glucose regulation in neonate and consequences in neonatal management]

Glucose homeostasis during fetal life depends entirely on continuous placental glucose transfer. Fetal endocrine milieu is characterized by high insulin which has mainly anabolic action. During third trimester, insulin promotes energetic stores as glycogen and fat deposition. At birth, constant maternal supply is interrupted and this is accompanied by a surge in glucagon and catecholamine levels and a decrease in insulin level. These hormonal changes induce hepatic glucose production provided by glycogenolysis during the first hours of life and then by gluconeogenesis. They also promote lipolysis which generates glycerol, a gluconeogenic substrate and free fatty acids. Free fatty acids provide gluconeogenesis activating factors and ketone bodies which represent alternative fuels for brain metabolism. Equilibrium between tissue consumption of glucose, hepatic glucose production and exogenous glucose supply maintains blood glucose level. If one of these mechanisms fails, hypoglycaemia may occur. Hypoglycaemia is predictable in three situations: depletion of energetic stores (prematurity and intra-uterine growth restriction), increase tissue energetic consumption and fetal hyperinsulinism. Blood glucose levels at which clinical interventions should be considered depend on operational thresholds. Therapeutic goal in case of hypoglycaemia is to increase blood glucose enhancing gluconeogenesis and providing continuous brain supply with glucose and ketone bodies. Paradoxically, many preterm infants less than 30 gestational weeks develop hyperglycaemia. There is evidence that processing of proinsulin in beta-cells is deficient and that preterm infants are partially resistant to insulin. Exogenous insulin infusion is efficient and may be used with caution.