Carbohydrate metabolism in the fetus and neonate and altered neonatal glucoregulation

A shift from glycolytic and fatty acid derivatives toward one-carbon metabolites in the developing lung during transitions of the early postnatal period

During postnatal lung development, metabolic changes that coincide with stages of alveolar formation are poorly understood. Responding to developmental and environmental factors, metabolic changes can be rapidly and adaptively altered. The objective of the present study was to determine biological and technical determinants of metabolic changes during postnatal lung development. Over 118 metabolic features were identified by liquid chromatography with tandem mass spectrometry (LC-MS/MS, Sciex QTRAP 5500 Triple Quadrupole). Biological determinants of metabolic changes were the transition from the postnatal saccular to alveolar stages and exposure to 85% hyperoxia, an environmental insult. Technical determinants of metabolic identification were brevity and temperature of harvesting, both of which improved metabolic preservation within samples. Multivariate statistical analyses revealed the transition between stages of lung development as the period of major metabolic alteration. Of three distinctive groups that clustered by age, the saccular stage was identified by its enrichment of both glycolytic and fatty acid derivatives. The critical transition between stages of development were denoted by changes in amino acid derivatives. Of the amino acid derivatives that significantly changed, a majority were linked to metabolites of the one-carbon metabolic pathway. The enrichment of one-carbon metabolites was independent of age and environmental insult. Temperature was also found to significantly influence the metabolic levels within the postmortem sampled lung, which underscored the importance of methodology. Collectively, these data support not only distinctive stages of metabolic change but also highlight amino acid metabolism, in particular one-carbon metabolites as metabolic signatures of the early postnatal lung.

High Maternal Body Mass Index Is Associated with an Early-Onset of Overweight/Obesity in Pre-School-Aged Children in Malawi. A Multilevel Analysis of the 2015-16 Malawi Demographic and Health Survey

BACKGROUND

Overweight/obesity in young children is one of the most serious public health issues globally. We examined whether individual- and community-level maternal nutritional status is associated with an early onset of overweight/obesity in pre-school-aged children in Malawi.

DESIGN

Data were obtained from the 2015-16 Malawi Demographic and Health Survey (MDHS). The maternal nutritional status as body mass index and childhood overweight/obesity status was assessed by using the World Health Organization (WHO) recommendations. To examine whether the maternal nutritional status is associated with overweight/obesity in pre-school-aged children, two-level multilevel logistic regression models were constructed on 4023 children of age less than five years dwelling in 850 different communities.

RESULTS

The multilevel regression analysis showed that children born to overweight/obese mothers had increased odds of being overweight/obese [adjusted odds ratio (aOR) = 3.11; 95% confidence interval (CI): 1.13-8.54]. At the community level, children born to mothers from the middle (aOR: 1.68; 95% CI: 1.02-2.78) and high (aOR: 1.69; 95% CI: 1.00-2.90) percentage of overweight/obese women had increased odds of being overweight/obese. In addition, there were significant variations in the odds of childhood overweight/obesity in the communities.

CONCLUSIONS

Strategies aimed at reducing childhood overweight/obesity in Malawi should address not only women and their children but also their communities. Appropriate choices of nutrition, diet and physical activity patterns should be emphasized upon in overweight/obese women of childbearing age throughout pregnancy and beyond.

Does hyperglycemia in hypernatremic preterm infants increase the risk of intraventricular hemorrhage?

OBJECTIVE

Hypernatremia and hyperglycemia are highly prevalent in preterm infants during the first week after birth, and both can lead to hyperosmolarity and osmotic shifts. The objective is to determine whether hyperglycemia increases the risk of intraventricular hemorrhage (IVH) in hypernatremic preterm infants.

STUDY DESIGN

Single-center retrospective medical record review of 216 infants <1000 g birth weight and <29 weeks gestational age (admitted over a 9-year period) who had serum sodium levels and blood glucose levels monitored at least every 24 h and more frequently if indicated during the first 10 days after birth. Hyperglycemia was defined as persistently high blood glucose (usually >200 mg dl(-1)) treated with an insulin infusion. Hypernatremia was defined as a serum sodium level of ⩾150 mmol l(-1) on repeated measurements.

RESULTS

Of the 216 infants studied, 76 (35%) developed hyperglycemia and 126 (58%) developed hypernatremia. IVH developed more frequently in infants with hyperglycemia (P=0.006, odds ratio (OR) 2.3, 95% confidence interval (CI) 1.3 to 4.1), in infants with hypernatremia (P=0.018, OR 2.0, 95% CI 1.2 to 3.5) and in infants with hypernatremia plus hyperglycemia (P=0.001, OR 3.2, 95% CI 1.6 to 6.4). Multivariate regression analysis confirmed the independent association of higher risk of IVH with the presence of hypernatremia plus hyperglycemia (P=0.015, OR 2.6, 95% CI 1.2 to 5.5) but not with hypernatremia or hyperglycemia alone.

CONCLUSION

Hyperglycemia increases the risk of IVH in hypernatremic preterm infants.

Instability of glucose values in very preterm babies at term postmenstrual age

OBJECTIVE

To determine if very preterm (VPT) babies are capable of maintaining glucose levels within normal ranges at or near term postmenstrual age.

STUDY DESIGN

Glucose levels were intermittently or continuously monitored during 48 hours in a cohort of 60 VPT infants near hospital discharge. Hypoglycemic (≤45 mg/dL, 2.5 mmol/L) and hyperglycemic (≥140 mg/dL or 7.8 mmol/L, severe if ≥180 mg/dL or 10 mmol/L) episodes were considered relevant if they lasted longer than 30 minutes. Feeding regimes followed current practice.

RESULTS

With intermittent capillary, 2 hypoglycemic values and another 3 that were abnormally high were detected. With continuous monitoring, 6 babies (10.0%) had isolated hypoglycemia ≤45 mg/dL (2.5 mmol/L) (3 of them reaching 40 mg/dL, 2.2 mmol/L), 14 (23.3%) had isolated hyperglycemia, and 8 (13.3%) had episodes of both. The mean duration of hypoglycemia per patient was 2.8 ± 2.9 hours and 4.68 ± 4.35 hours in the case of hyperglycemia, with 12 infants becoming severely hyperglycemic. Of the 12 severely hyperglycemic patients, 5 also developed severe hypoglycemia. No specific characteristics identified the hypoglycemic babies. A history of intrauterine growth restriction (P = .037) and female sex (P = .063) seemed to increase the risk of severe hyperglycemia.

CONCLUSIONS

VPT infants continue to have abnormal glucose values, especially hyperglycemia, by the time of hospital discharge. No specific factors identify babies at higher risk for hypoglycemia, and intrauterine growth restriction and female sex seemed to predispose to hyperglycemia.

Respiratory quotient evolution during normal pregnancy: what nutritional or clinical information can we get out of it?

Food intake increases to a varying extent during pregnancy to provide extra energy for the growing fetus. Measuring the respiratory quotient (RQ) during the course of pregnancy (by quantifying O2 consumption and CO2 production with indirect calorimetry) could be potentially useful since it gives an insight into the evolution of the proportion of carbohydrate vs. fat oxidized during pregnancy and thus allows recommendations on macronutrients for achieving a balanced (or slightly positive) substrate intake. A systematic search of the literature for papers reporting RQ changes during normal pregnancy identified 10 papers reporting original research. The existing evidence supports an increased RQ of varying magnitude in the third trimester of pregnancy, while the discrepant results reported for the first and second trimesters (i.e. no increase in RQ), explained by limited statistical power (small sample size) or fragmentary data, preclude safe conclusions about the evolution of RQ during early pregnancy. From a clinical point of view, measuring RQ during pregnancy requires not only sophisticated and costly indirect calorimeters but appears of limited value outside pure research projects, because of several confounding variables: (1) spontaneous changes in food intake and food composition during the course of pregnancy (which influence RQ); (2) inter-individual differences in weight gain and composition of tissue growth; (3) technical factors, notwithstanding the relatively small contribution of fetal metabolism per se (RQ close to 1.0) to overall metabolism of the pregnant mother.

Glucose metabolism in the late preterm infant

Prematurity and low birth weight are important determinants of neonatal morbidity and mortality. A rising trend of preterm births is caused by an increase in the birth rate of near-term infants. Near-term infants are defined as infants of 34 to 36 6/7 weeks gestation. It is dangerous to assume that the incidence of hypoglycemia in the later preterm infant is similar to the infant born at full term. Although current methods for assessing effects of hypoglycemia are imperfect, the injury to central nervous system depends on the degree of prematurity, presence of intrauterine growth restriction (IUGR), intrauterine compromise, genotype, blood flow, metabolic rate, and availability of other substrates. Therefore, early recognition of glucose metabolic abnormalities pertaining to late preterm infants is essential to provide appropriate and timely interventions in the newborn nursery. Although many of the investigations have targeted full-term infants, premature infants inclusive of the extremely low birth weight infants and the intrauterine growth-restricted infants, adequately powered studies restricted to only the late preterm infants are required and need future consideration.

Total parenteral nutrition-associated hyperglycemia correlates with prolonged mechanical ventilation and hospital stay in septic infants

PURPOSE

We studied the effects of total parenteral nutrition (TPN)-associated hyperglycemia on the clinical outcome in premature septic infants in the neonatal intensive care unit.

METHODS

The charts of all premature infants weighing less than 1500 g upon admission to the neonatal intensive care unit between January 1, 2002, and December 31, 2002, with sepsis, ventilator dependence, and feeding intolerance were studied. Maximum serum glucose concentrations were compared with duration of TPN, mechanical ventilation, hospital length of stay, and survival using Pearson regression analysis and Student's t test.

RESULTS

Thirty-seven patients met the search criteria. The average caloric intake for all infants at the time of blood culture-proven sepsis was 83 +/- 19 kcal/kg per day. The maximum serum glucose concentration (milligrams per deciliter) after having positive blood cultures (sepsis) was positively correlated with the duration of TPN (r = 0.45, P = .005), length of dependence on mechanical ventilation (r = 0.45, P = .006), and hospital length of stay (r = 0.36, P = .03). The average maximum serum glucose level was significantly higher in the nonsurviving infants (241 +/- 46 vs 141 +/- 48, P < .0001).

CONCLUSION

Hyperglycemia correlated with prolonged ventilator dependency and increased hospital length of stay in premature septic infants. Avoidance of excessive nutrient delivery and tight glycemic control during periods of acute metabolic stress may improve outcome in this patient population.

Selected principles of perinatal-neonatal glucose metabolism

While the fetus is completely dependent on his/her mother for glucose and other nutrient transfer across the placenta, the adult is completely independent, especially one who is neither pregnant nor diabetic. The neonate is considered to be in a transition between the complete dependence of the fetus and the complete independence of the adult. The heterogeneity that is the hallmark of neonatal glucose metabolism is illustrated by the observation that maintenance of euglycaemia in the sick and/or low-birthweight neonate is especially difficult. This reinforces the concept that the neonate is vulnerable to carbohydrate disequilibrium. In this discussion, we shall first evaluate the definition of euglycaemia by considering the ranges for hypo- and hyperglycaemia. We shall also review the considerable literature that has been published on measurement of the rate of glucose production and the rate of glucose utilization in the neonate. This review highlights where further work is necessary to understand the developing maturation (i.e. control) of glucose homeostasis in the neonate.

Both relative insulin resistance and defective islet beta-cell processing of proinsulin are responsible for transient hyperglycemia in extremely preterm infants

OBJECTIVE

Many extremely preterm infants develop hyperglycemia in the first week of life during continuous glucose infusion. The objective of this study was to determine whether defective insulin secretion or resistance to insulin was the primary factor involved in transient hyperglycemia of extremely preterm infants.

METHODS

A prospective comparative study was conducted in appropriate-for-gestational-age preterm infants <30 weeks of gestational age with the aim specifically to evaluate the serum levels of proinsulin, insulin, and C-peptide secreted during transient hyperglycemia by specific immunoassays. Three groups of infants were investigated hyperglycemic (n = 15) and normoglycemic preterm neonates (n = 12) and normal, term neonates (n = 21). In addition, the changes in beta-cell peptide levels were analyzed during and after intravenous insulin infusion in the hyperglycemic group. Data were analyzed using analysis of variance and analysis of variance for repeated measures.

RESULTS

At inclusion, insulin and C-peptide levels did not differ in hyperglycemic subjects and in preterm controls. Proinsulin concentration was significantly higher in the hyperglycemic group (36.5 +/- 3.9 vs 23.2 +/- 0.9 pmol/L). Compared with term neonates, proinsulin and C-peptide levels were higher in normoglycemic preterm infants (23.2 +/- 0.9 vs 18.9 +/- 2.71 pmol/L and 1.67 +/- 0.3 vs 0.62 +/- 0.12 nmol/L, respectively). During and after insulin infusion in hyperglycemic neonates, plasma glucose concentration fell and proinsulin and C-peptide levels were lowered (18.4 +/- 7.6 and 20.7 +/- 4.5 pmol/L, respectively).

CONCLUSION

These data suggest that 1) preterm neonates are sensitive to changes in plasma glucose concentration, but proinsulin processing to insulin is partially defective in hyperglycemic preterm neonates; 2) hyperglycemic neonates are relatively resistant to insulin because higher insulin levels are needed to achieve euglycemia in this group compared with normoglycemic neonates. These results also show that insulin infusion is beneficial in extremely preterm infants with transient hyperglycemia.

Regulation of brain water during acute glucose-induced hyperosmolality in ovine fetuses, lambs, and adults

We tested the hypothesis that, during acute glucose-induced hyperosmolality, the brain shrinks less than predicted on the basis of an ideal osmometer and that brain volume regulation is present in fetuses, premature and newborn lambs. Brain water responses to glucose-induced hyperosmolality were measured in the cerebral cortex, cerebellum, and medulla of fetuses at 60% of gestation, premature ventilated lambs at 90% of gestation, newborn lambs, and adult sheep. After exposure of the sheep to increases in osmolality with glucose plus NaCl, brain water and electrolytes were measured. The ideal osmometer is a system in which impermeable solutes do not enter or leave in response to an osmotic stress. In the absence of volume regulation, brain solute remains constant as osmolality changes. The osmotically active solute demonstrated direct linear correlations with plasma osmolality in the cerebral cortex of the fetuses at 60% of gestation (r = 0.72, n = 24, P = 0.0001), premature lambs (r = 0.58, n = 22, P = 0.005), newborn lambs (r = 0.57, n = 24, P = 0.004), and adult sheep (r = 0.70, n = 18, P = 0.001). Similar findings were observed in the cerebellum and medulla. Increases in the quantity of osmotically active solute over the range of plasma osmolalities indicate that volume regulation was present in the brain regions of the fetuses, premature lambs, newborn lambs, and adult sheep during glucose-induced hyperosmolality. We conclude that, during glucose-induced hyperosmolality, the brain shrinks less than predicted on the basis of an ideal osmometer and exhibits volume regulation in fetuses at 60% of gestation, premature lambs, newborn lambs, and adult sheep.

Glucose homeostasis in the micropremie

This article evaluates the current knowledge of the kinetics of glucose homeostasis in the micropremie. Glucose production, glucose use, and glucose oxidation are reviewed in detail. This article also evaluates the developmental regulation of glucose homeostasis relative to some of the fundamental differences known to exist in the neonate compared to the adult.

Hypoglycemia in infants and children

Hypoglycemia is more common in the pediatric patient than in adults. This article discusses the many diagnoses that can be associated with hypoglycemia in infancy and childhood. A guide to help practitioners evaluate such patients and suggested treatments for many of these disorders are provided. As genetic diagnosis continues to develop, it is anticipated that the list of specific disorders associated with hypoglycemia in infancy and childhood will increase.

Neonatal hypoglycemia, part II: pathophysiology and therapy

Contemporary research is elucidating both the molecular mechanisms of hypoglycemia-induced neuronal injury and its corresponding clinical manifestations. Recognizing and screening those neonates at highest risk of hypoglycemia-induced injury is an important skill for all physicians responsible for the care of newborns. Appropriate therapy, consisting of either oral or intravenous glucose, should never be delayed while one is awaiting laboratory confirmation of a "low" glucose level.

[Transitory hyperinsulinism with hypoglycemia in asphyxia neonatorum]

BACKGROUND

Hypoglycemia is a well-known complication in neonates small for gestational age and in those with diabetic mothers. Birth asphyxiated infants can develop severe hypoglycemia due to reduced glycogen stores.

CASE REPORTS

The first patient was born at 41 weeks, weighing 3,780 g by emergency cesarean section because of fetal distress. He developed a pneumothorax and hypoglycemia. He was given glucose infusion (at day 4: 20 mg/kg/d). Hyperinsulinism was confirmed: blood levels at 18.3 mU/L on day 1 and 11.7 mU/L on day 2. The infusion rate was gradually decreased. The second patient was born at 39 weeks, weighing 2,780 g by emergency cesarean section because of fetal distress. She needed glucose infusion (24 g/kg/d) because of hypoglycemia with hyperinsulinism (12.8 mU/L on day 2 and 11.7 mU/L on day 3). After 5 days, the infusion of glucose was replaced by oral feeding only.

CONCLUSION

Transient hypoglycemia in asphyxiated newborn infants with hyperinsulinism must be considered even when hypoglycemia may be difficult to prove.

Attenuated hepatic glucose production but unimpaired lipolysis in newborn infants of mothers with diabetes

In infants of diabetic mothers, maternal-fetal hyperglycemia induces fetal hyperinsulinemia, which may be sustained for several hours after birth. The inhibitory effect of insulin on glycogenolysis, gluconeogenesis, and lipolysis increases the risk of hypoglycemia in these infants. Eight term infants of diabetic mothers were studied between 3.9 and 8.5 h postnatally. The maternal diabetes was considered well controlled as judged by self-monitoring of blood glucose and Hb Alc. Neonatal plasma concentrations of glucose, glycerol, and insulin were monitored and averaged 2.7 +/- 0.7 mM, 371 +/- 116 microM, and 15.9 +/- 2.8 microU.mL-1, respectively. Stable isotope-gas chromatography/ mass spectrometry techniques were used to determine glucose and glycerol turnover rates and gluconeogenesis from glycerol in the infants. The appearance rates of glucose and glycerol averaged 20.0 +/- 5.4 mumol.kg-1.min-1 (3.6 +/- 1.0 mg.kg-1.min-1), and 8.9 +/- 2.3 mumol.kg-1.min-1, respectively. The fraction of glycerol appearance rate converted to glucose was 68.2 +/- 17.3%, which accounted for 15.5 +/- 4.6% of glucose production. Thus, compared with healthy term infants studied previously under identical conditions, the infants of diabetic mothers had higher insulin concentrations and attenuated glucose production. Despite increased insulin concentrations, lipolysis was unimpaired, and the gluconeogenic contribution from glycerol was higher than in the healthy newborns.

Assessing fluid and electrolyte status in the newborn

Fluid and electrolyte assessment during the first week of life is complicated by rapid changes in fluid and electrolyte balance during the transition from fetal to neonatal life and by the newborn’s small size. A physiologic decrease in extracellular water volume, as well as a transient increase in serum potassium and transient decreases in plasma glucose and total plasma ionized calcium concentrations must be taken into account. In general, the more immature the newborn, the greater the changes that can be expected. The use of plasma creatinine as an indicator of glomerular filtration rate is limited because it is a function of maternal renal function at birth and because of non-steady-state conditions in the immediate postnatal period. Guidelines for monitoring schedules are provided on the basis of these physiologic considerations and the author’s experience. Method of blood sampling and time to separation of serum are important considerations in interpreting results. Minimization of sample volume is critical to minimize blood transfusion requirements. Clinicians should be aware of the analytical error associated with these measurements in their own institutions. Reference ranges are provided.

Glycerol carbon contributes to hepatic glucose production during the first eight hours in healthy term infants

The newborn infant must mobilize endogenous substrate stores to meet the requirements of glucose-dependent organs. High concentrations of free fatty acids and glycerol, and a rapid decrease in the respiratory quotient, indicate that lipids are an important fuel soon after birth. The purpose of the present study was to determine the onset of lipolysis and gluconeogenesis from glycerol in healthy, term, unfed infants. Eight infants were studied from a postnatal age of 3.5 +/- 0.5 h to 7.4 +/- 0.2 h using [6,6-2H2] glucose and [2-13C]glycerol analysed by gas chromatography/mass spectrometry. Plasma concentrations of glucose, glycerol and insulin averaged 2.9 +/- 0.4 mM, 369 +/- 89 microM and 9.4 +/- 9.4 +/- 3.7 microU.ml-1, respectively. The hepatic glucose production rate averaged 25.0 +/- 3.5 mumol.kg-1 min-1 (4.5 +/- 0.6 mg.kg-1.min-1) and the endogenous plasma appearance rate of glycerol 8.7 +/- 1.2 mumol.kg-1.min. On average, 57.9 +/- 8.4% of the glycerol was converted to glucose, representing 11.1 +/- 2.3% of hepatic glucose output. Thus, lipolysis and gluconeogenesis from glycerol are established within the first 8 h of life in term infants.

Extremely preterm infants (< 28 weeks) are capable of gluconeogenesis from glycerol on their first day of life

Extremely preterm infants have been shown capable of producing glucose at a rate comparable to that of term infants, but virtually no data are available on their capacity for lipolysis and gluconeogenesis. To address this issue, we studied the flux of glycerol and its gluconeogenic contribution to hepatic glucose output by determining the endogenous plasma appearance rate of glycerol (glycerol Ra) and its conversion to glucose in 10 newborn infants, 24-27 wk of gestational age. The study was performed during the 1st d of life by tracer dilution technique using [6,6-2H2]glucose and [2-13C]glycerol given as constant rate i.v. infusions. Plasma isotopic enrichments of the tracers were obtained by gas chromatography/mass spectrometry. Endogenous glycerol Ra ranged from 2.4 to 21.6 (median 5.0) mumol.kg-1.min-1, of which 31.5% (25.6-64.4%) was converted to glucose. The glucose production rate averaged 17.5 +/- 5.4 mumol.kg-1.min-1 (3.2 +/- 1.0 mg.kg-1.min-1), of which 5.0% (1.6-37.6%) was derived from glycerol. The results show that extremely preterm infants, despite limited fat stores, are capable of generating glycerol at a rate within the range reported for term and near term newborns. The infants were also capable of converting part of this glycerol to glucose, providing a contribution to hepatic glucose production comparable to that found in more mature newborns.

Fetal growth velocity: kinetic, clinical, and biological aspects

With the aim of determining fetal growth kinetics, prenatal data were analysed which had been longitudinally collected in the framework of a perinatal growth survey. The sample comprised 238 singleton normal pregnancies, selected in Genoa and Turin (between 1987 and 1990), and repeatedly assessed by ultrasound scans (five to nine per pregnancy). Five morphometric traits were considered: BPD (biparietal diameter), OFD (occipitofrontal diameter), HC (head circumference), FDL (femur diaphysis length) and AC (abdomen circumference). Growth rate seemed to increase in the early part of the second trimester, and decrease subsequently: velocity peaks were steeper and earlier for head diameters and circumference (about 18 weeks) than for femur length (20 weeks) and abdomen circumference (22 weeks). Velocity standards were traced using a longitudinal two-stage linear model: this ensures unbiased description of the shape of the growth curve, even when growth kinetics are asynchronous, and efficient estimation of the outer centiles--the most useful for diagnostic purposes.

Continuous infusion of insulin in hyperglycemic low-birth weight infants receiving parenteral nutrition with and without lipid emulsion

The efficiency of a continuous infusion of insulin in improving glucose tolerance was compared in two groups of very low-birth weight infants (mean +/- SEM birth weights 757 +/- 40 vs 828 +/- 80 g and gestational ages 27.6 +/- 0.7 vs. 27.2 +/- 0.5 weeks) receiving total parenteral nutrition with and without the addition of lipid emulsion to the nutrition regimen. The mean +/- SEM cumulative doses of insulin (0.87 +/- 0.1 vs 1.15 +/- 0.3 U/kg) and hours required to decrease the blood glucose level to 120 mg/dL (9.1 +/- 0.8 vs 9.5 +/- 1.0 hours) were similar. Insulin was delivered with a syringe pump used for other routine purposes in the neonatal intensive care unit. Continuous intravenous insulin infusion is an effective, inexpensive, safe method for maintaining glucose homeostasis in low-birth weight infants who develop hyperglycemia as a consequence of total parenteral nutrition.

A controlled trial of insulin infusion and parenteral nutrition in extremely low birth weight infants with glucose intolerance

To determine whether a continuous insulin infusion improves glucose tolerance in extremely low birth weight infants, we conducted a prospective, randomized trial in 24 neonates 4 to 14 days old (mean birth weight 772.9 +/- 128 gm; mean gestational age 26.3 +/- 1.6 weeks). Infants who had glucose intolerance were randomly assigned to receive either intravenous glucose and total parenteral nutrition with insulin through a microliter-sensitive pump or standard intravenous therapy alone. One infant assigned to receive insulin never required it. The groups were similar in birth weight, gestational age, race, gender, medical condition, and energy intake before the study. The mean duration of therapy was 14.6 days (range 7 to 21 days). During the study, the 11 insulin-treated infants tolerated higher glucose infusion rates (20.1 +/- 2.5 vs 13.2 +/- 3.2 mg/kg/min (1.1 +/- 0.1 vs 0.7 +/- 0.2 mmol/L); p less than 0.01), had greater nonprotein energy intake (124.7 +/- 18 vs 86.0 +/- 6 kcal/kg/day; p less than 0.01), and had better weight gain (20.1 +/- 12.1 vs 7.8 +/- 5.1 gm/kg/day; p less than 0.01) than the 12 control infants. The incidence of hypoglycemia, electrolyte imbalance, chronic lung disease, and death did not differ between groups. We conclude that a controlled insulin infusion improves and sustains glucose tolerance, facilitates provision of calories, and enhances weight gain in glucose-intolerant premature infants.

Neonatal hypoglycemia following maternal glucose infusion prior to delivery

Intravenous glucose therapy to mother prior to delivery significantly affects glucose and insulin homeostasis in fetus and newborn infants. Specifically, the infants show hyperglycemia, and hyperinsulinism at birth, and are predisposed to hypoglycemia in the first few hours of life. In this paper we have focussed attention on the clinical significance of these changes and suggest some remedial measures, in light of our own research.

Transient hypoglycemia with hyperinsulinemia in a newborn infant with Rubinstein-Taybi syndrome

A newborn boy with Rubinstein-Taybi syndrome who had profound neonatal hypoglycemia is presented. The infant was a discordant fraternal twin with intrauterine growth retardation. The hypoglycemia was due to transient hyperinsulinemia, a condition often seen in small-for-gestational-age infants. Neonatal hypoglycemia may be common in infants with Rubinstein-Taybi syndrome, especially if they also have intrauterine growth retardation.

Prolonged hyperinsulinism and hypoglycemia. In an asphyxiated, small for gestation infant. Case management and literature review

The authors describe a term female, asphyxiated, small for gestational age (SGA) infant with documented hyperinsulinism and hypoglycemia occurring at approximately 45 hours of age. The hypoglycemia was refractory to a high rate glucose infusion and steroid administration but responded to diazoxide. The subsequent hospital course was complicated by right-sided heart failure and sepsis. With the onset of sepsis, a transient hyperglycemia was noted that required intermittent insulin therapy for 10 days. Hypoglycemia and hyperinsulinism reemerged and responded to diazoxide therapy. An attempt to discontinue diazoxide at age 6 months was aborted at 2 weeks when hyperinsulinism and hypoglycemia recurred. The infant required diazoxide for 7 more months, then she recovered without having any sequelae. The review of this uncommon hypoglycemia etiology in an SGA and asphyxiated infant and the merits of long-term diazoxide treatment are discussed.

Effect of diazoxide or glucagon on hepatic glucose production rate during extreme neonatal hypoglycaemia

The relation between hepatic glucose production rate (HGPR) and plasma concentrations of insulin and glucagon was investigated in four term neonates who had severe hypoglycaemia. The hepatic glucose production rate was less than 20% of normal for fasting term neonates in all four babies and yet insulin concentrations were never greater than 12 microU/ml; two babies had very low glucagon concentrations (less than 60 ng/l). Two further neonates with similar histories also had plasma glucagon concentrations that were also extremely low (less than 20 ng/l). A single intravenous bolus of glucagon caused a rapid rise in hepatic glucose production rate towards the normal range, which was sustained for many hours after the bolus had been given. Diazoxide given to one baby suppressed previously 'normal' insulin concentrations still further (4.2 to less than 1.6 microU/ml) and thereby restored the hepatic glucose production rate to normal. In view of the normal plasma insulin concentrations at a time when the hepatic glucose production rate was reduced, we feel that the absolute concentration of insulin may be less important than the insulin/glucagon molar ratio in the control of glucose homeostasis in this group of infants. The changing of this ratio by means of boluses of glucagon may be useful in preventing rebound hypoglycaemia, which so often occurs when dextrose infusions are reduced either accidentally or in an attempt to restart oral feeds.