Neonatal Glycemia and Neurodevelopmental Outcomes at 2 Years

BACKGROUND

Neonatal hypoglycemia is common and can cause neurologic impairment, but evidence supporting thresholds for intervention is limited.

METHODS

We performed a prospective cohort study involving 528 neonates with a gestational age of at least 35 weeks who were considered to be at risk for hypoglycemia; all were treated to maintain a blood glucose concentration of at least 47 mg per deciliter (2.6 mmol per liter). We intermittently measured blood glucose for up to 7 days. We continuously monitored interstitial glucose concentrations, which were masked to clinical staff. Assessment at 2 years included Bayley Scales of Infant Development III and tests of executive and visual function.

RESULTS

Of 614 children, 528 were eligible, and 404 (77% of eligible children) were assessed; 216 children (53%) had neonatal hypoglycemia (blood glucose concentration, <47 mg per deciliter). Hypoglycemia, when treated to maintain a blood glucose concentration of at least 47 mg per deciliter, was not associated with an increased risk of the primary outcomes of neurosensory impairment (risk ratio, 0.95; 95% confidence interval [CI], 0.75 to 1.20; P=0.67) and processing difficulty, defined as an executive-function score or motion coherence threshold that was more than 1.5 SD from the mean (risk ratio, 0.92; 95% CI, 0.56 to 1.51; P=0.74). Risks were not increased among children with unrecognized hypoglycemia (a low interstitial glucose concentration only). The lowest blood glucose concentration, number of hypoglycemic episodes and events, and negative interstitial increment (area above the interstitial glucose concentration curve and below 47 mg per deciliter) also did not predict the outcome.

CONCLUSIONS

In this cohort, neonatal hypoglycemia was not associated with an adverse neurologic outcome when treatment was provided to maintain a blood glucose concentration of at least 47 mg per deciliter. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and others.).

Glucocorticoid-Induced Preterm Birth and Neonatal Hyperglycemia Alter Ovine β-Cell Development

Adults born preterm are at increased risk of impaired glucose tolerance and diabetes. Late gestation fetuses exposed to high blood glucose concentration also are at increased risk of impaired glucose tolerance as adults. Preterm babies commonly become hyperglycemic and are thus exposed to high blood glucose concentration at an equivalent stage of pancreatic maturation. It is not known whether preterm birth itself, or complications of prematurity, such as hyperglycemia, alter later pancreatic function. To distinguish these, we made singleton preterm lambs hyperglycemic (HYPER) for 12 days after birth with a dextrose infusion and compared them with vehicle-treated preterm and term controls and with HYPER lambs made normoglycemic with an insulin infusion. Preterm birth reduced β-cell mass, apparent by 4 weeks after term and persisting to adulthood (12 mo), and was associated with reduced insulin secretion at 4 months (juvenile) and reduced insulin mRNA expression in adulthood. Hyperglycemia in preterm lambs further down-regulated key pancreatic gene expression in adulthood. These findings indicate that reduced β-cell mass after preterm birth may be an important factor in increased risk of diabetes after preterm birth and may be exacerbated by postnatal hyperglycemia.

Randomised trial of neonatal hypoglycaemia prevention with oral dextrose gel (hPOD): study protocol

Background

Neonatal hypoglycaemia is common, affecting up to 15 % of newborn babies and 50 % of those with risk factors (preterm, infant of a diabetic, high or low birthweight). Hypoglycaemia can cause brain damage and death, and babies born at risk have an increased risk of developmental delay in later life.

Treatment of hypoglycaemia usually involves additional feeding, often with infant formula, and admission to Neonatal Intensive Care for intravenous dextrose. This can be costly and inhibit the establishment of breast feeding.

Prevention of neonatal hypoglycaemia would be desirable, but there are currently no strategies, beyond early feeding, for prevention of neonatal hypoglycaemia. Buccal dextrose gel is safe and effective in treatment of hypoglycaemia. The aim of this trial is to determine whether 40 % dextrose gel given to babies at risk prevents neonatal hypoglycaemia and hence reduces admission to Neonatal Intensive Care.

Methods/design

Design: Randomised, multicentre, placebo controlled trial.

Inclusion criteria: Babies at risk of hypoglycaemia (preterm, infant of a diabetic, small or large), less than 1 h old, with no apparent indication for Neonatal Intensive Care Unit admission and mother intends to breastfeed.

Trial entry & randomisation: Eligible babies of consenting parents will be allocated by online randomisation to the dextrose gel group or placebo group, using a study number and corresponding trial intervention pack.

Study groups: Babies will receive a single dose of 0.5 ml/kg study gel at 1 h after birth; either 40 % dextrose gel (200 mg/kg) or 2 % hydroxymethylcellulose placebo. Gel will be massaged into the buccal mucosal and followed by a breast feed.

Primary study outcome: Admission to Neonatal Intensive Care.

Sample size: 2,129 babies are required to detect a decrease in admission to Neonatal Intensive Care from 10–6 % (two-sided alpha 0.05, 90 % power, 5 % drop-out rate).

Discussion

This study will investigate whether admission to Neonatal Intensive Care can be prevented by prophylactic oral dextrose gel; a simple, cheap and painless intervention that requires no special expertise or equipment and hence is applicable in almost any birth setting.

Trial registration

Australian New Zealand Clinical Trials Registry - ACTRN 12614001263684.

Hyperglycaemic Preterm Babies Have Sex Differences in Insulin Secretion

BACKGROUND

Hyperglycaemia is a common complication of prematurity and is associated with neonatal mortality and morbidity, yet the aetiology is incompletely understood. C-peptide has been used in adults to estimate endogenous insulin secretion due to its simple clearance kinetics.

OBJECTIVE

To determine insulin secretion calculated from plasma C-peptide concentrations in hyperglycaemic preterm babies.

METHODS

This is a retrospective analysis of a cohort of 41 very preterm babies with a median gestational age of 27.2 weeks (26.2-28.7) enrolled in a randomised controlled trial of tight glycaemic control when they developed hyperglycaemia (2 consecutive blood glucose concentrations, BGC, > 8.5 mmol·l(-1)). Insulin secretion was determined using a steady state analysis of a 2-compartment C-peptide kinetic model.

RESULTS

BGC, plasma insulin concentration, plasma C-peptide concentrations, and insulin secretion were higher at randomisation than 1-2 weeks following randomisation (p ≤ 0.02). Insulin secretion was higher in girls at 11.7 mU·l(-1)·kg(-1)·min(-1) (5.3-18.7) vs. 4.7 mU·l(-1)·kg(-1)·min(-1) (2.1-8.3; p < 0.005), with no difference in clinical characteristics, BGC, plasma insulin concentration, or nutrition between the sexes (p > 0.25). Insulin secretion was lower in samples taken during exogenous insulin delivery at 3.7 mU·l(-1)·kg(-1)·min(-1) (1.8-6.9) vs. 9.8 mU·l(-1)·kg(-1)·min(-1) (4.7-17.8; p = 0.02).

CONCLUSIONS

Insulin secretion was higher when babies had higher BGC, indicating that endogenous insulin secretion is sensitive to BGC. Girls had higher insulin secretion, at similar blood glucose and plasma insulin concentrations, than boys.

Brain mass estimation by head circumference and body mass methods in neonatal glycaemic modelling and control

INTRODUCTION

Hyperglycaemia is a common complication of stress and prematurity in extremely low-birth-weight infants. Model-based insulin therapy protocols have the ability to safely improve glycaemic control for this group. Estimating non-insulin-mediated brain glucose uptake by the central nervous system in these models is typically done using population-based body weight models, which may not be ideal.

METHOD

A head circumference-based model that separately treats small-for-gestational-age (SGA) and appropriate-for-gestational-age (AGA) infants is compared to a body weight model in a retrospective analysis of 48 patients with a median birth weight of 750g and median gestational age of 25 weeks. Estimated brain mass, model-based insulin sensitivity (SI) profiles, and projected glycaemic control outcomes are investigated. SGA infants (5) are also analyzed as a separate cohort.

RESULTS

Across the entire cohort, estimated brain mass deviated by a median 10% between models, with a per-patient median difference in SI of 3.5%. For the SGA group, brain mass deviation was 42%, and per-patient SI deviation 13.7%. In virtual trials, 87-93% of recommended insulin rates were equal or slightly reduced (Δ<0.16mU/h) under the head circumference method, while glycaemic control outcomes showed little change.

CONCLUSION

The results suggest that body weight methods are not as accurate as head circumference methods. Head circumference-based estimates may offer improved modelling accuracy and a small reduction in insulin administration, particularly for SGA infants.

Neonatal hyperglycaemia increases mortality and morbidity in preterm lambs

BACKGROUND

Hyperglycaemic preterm babies suffer increased mortality and morbidity, but it is not known if these associations are causal or if treatment with insulin improves outcome.

OBJECTIVES

We aimed to investigate the effect of neonatal hyperglycaemia, and its treatment with insulin, on mortality and morbidity in preterm lambs.

METHODS

Preterm lambs (137 days' gestation; term = 148 days) were randomised to a 12-day intravenous infusion of saline (PremC; n = 39), 50% dextrose (HYPER; n = 47), or 50% dextrose + insulin (INS; n = 21). Term controls (TermC; n = 19) received saline. Dextrose and insulin infusions were titrated to maintain blood glucose concentrations (BGC) at 10-12 mmol·l(-1) (HYPER) or 4-6 mmol·l(-1) (INS).

RESULTS

HYPER lambs had higher BGC (mean (SEM); TermC: 5.6 (0.1), PremC: 5.5 (0.1), HYPER: 10.8 (0.6), INS: 6.2 (0.3) mmol·l(-1); p < 0.0001), higher mortality (n (%); TermC: 0, PremC: 2 (5), HYPER: 11 (23), INS: 0; p < 0.001), higher incidence of fever (n (%); TermC: 3 (16), PremC: 13 (33), HYPER: 26 (55), INS: 6 (29); p = 0.01) and lower weight gain (mean (SEM); TermC: 45.9 (2.9), PremC: 44.2 (2.1), HYPER: 28.4 (1.9), INS: 28.7 (2.8) g·kg(-1)·day(-1); p < 0.0001).

CONCLUSIONS

Neonatal hyperglycaemia in preterm lambs causes increased mortality and morbidity, and decreases growth. Insulin treatment to restore euglycaemia attenuated the increased mortality and morbidity, but not the decreased growth.

Tight glycemic control with insulin in hyperglycemic preterm babies: a randomized controlled trial

OBJECTIVE

The optimal treatment of neonatal hyperglycemia is unclear. The aim of this trial was to determine whether tight glycemic control with insulin improves growth in hyperglycemic preterm infants, without increasing the incidence of hypoglycemia.

METHODS

Randomized, controlled, nonblinded trial of 88 infants born at <30 weeks' gestation or <1500 g who developed hyperglycemia (2 consecutive blood glucose concentrations (BGC) >8.5 mmol/L, 4 hours apart) and were randomly assigned to tight glycemic control with insulin (target BGC 4-6 mmol/L, "tight" group) or standard practice (restrictive guidelines for starting insulin, target BGC 8-10 mmol/L, "control" group). The primary outcome was linear growth rate to 36 weeks' postmenstrual age.

RESULTS

Eighty-eight infants were randomly assigned (tight group n = 43; control group n = 45). Infants in the tight group had a lesser lower leg growth rate (P < .05), but greater head circumference growth (P < .0005) and greater weight gain (P < .001) to 36 weeks' postmenstrual age than control infants. Tight group infants had lower daily BGC (median [interquartile range] 5.7 [4.8-6.7] vs 6.5 [5.1-8.2] mmol/L, P < .001) and greater incidence of hypoglycemia (BGC <2.6 mmol/L) (25/43 vs 12/45, P < .01) than controls. There were no significant differences in nutritional intake, or in the incidences of mortality or morbidity.

CONCLUSIONS

Tight glycemic control with insulin in hyperglycemic preterm infants increases weight gain and head growth, but at the expense of reduced linear growth and increased risk of hypoglycemia. The balance of risks and benefits of insulin treatment in hyperglycemic preterm neonates remains uncertain.

Survey of the management of neonatal hyperglycaemia in Australasia

AIM

Hyperglycaemia is a common problem in very low birthweight (VLBW) preterm neonates and has been associated with an increase in intraventricular haemorrhage and mortality. There are few data to guide clinicians on the best range of blood glucose levels to aim for when treating hyperglycaemic preterm babies with insulin. The aim of this study was to survey all Australasian tertiary neonatal intensive care units for their current practice in the definition and management of neonatal hyperglycaemia to aid in the design of a randomised controlled trial of the effect of tight glycaemic control on long-term outcome in VLBW babies.

METHODS

An online survey was sent to the 27 tertiary neonatal units in Australasia asking the respondents for details of their unit's definition and management of hyperglycaemia in VLBW infants.

RESULTS

Twenty-three tertiary neonatal units responded to the questionnaire. There were six different definitions of hyperglycaemia, with most units defining neonatal hyperglycaemia as a blood glucose level greater than 10 mM. There were large variations in the criteria for commencing insulin (blood glucose level 8-15 mM +/- glycosuria) and target blood glucose ranges for babies on insulin (ranging from 2.5-8 mM to 8-15 mM).

CONCLUSIONS

There is a wide variation in the management of neonatal hyperglycaemia between tertiary neonatal units in Australasia. This reflects the paucity of data available in this area. Further research on the management of neonatal hyperglycaemia is needed.