Neonatal hyperglycaemia increases mortality and morbidity in preterm lambs

A Higher Amount of Nutritional Intake as a Possible Cause of Hyperglycemia in Extremely Premature Infants in Parenteral and Enteral Nutrition at the Tertiary Neonatal Intensive Care Unit

BACKGROUND

This study aimed to find an association between infants who had hyperglycemia and those who did not, those treated with insulin or not and several prenatal and postnatal variables or the suboptimal prescription of parenteral nutrition.

METHODS

We conducted a retrospective study, which included extremely premature infants (<28 weeks of gestation) admitted to the tertiary NICU, University Medical Centre Ljubljana, between 1 January 2021 and 31 December 2021. Blood glucose measurements, insulin treatment, general characteristics, nutritional data and complications of prematurity were obtained retrospectively from hospital data.

RESULTS

There were 21 infants included in the study who did not receive insulin and 17 who were treated with insulin. Infants receiving insulin were younger and lighter compared to the non-insulin treatment group (mean gestational age 178 vs. 188 days; median birth weight 680 g vs. 990 g). The younger insulin group of infants received the same daily number of total macronutrients per kg per day compared to the older non-insulin group, i.e., glucose, lipids and amino acids, as recommended for the gestational age and birth weight. After adjusting for gestational age, no significant association with complications of prematurity was found.

CONCLUSIONS

The postulated explanation (with the prescription of a higher amount of macronutrients during the first seven days) for hyperglycemia and treatment with insulin in the less mature and lighter infants cannot be supported by the data given.

Hyperglycemia and prematurity: a narrative review

Hyperglycemia is commonly encountered in extremely preterm newborns and physiologically can be attributed to immaturity in several biochemical pathways related to glucose metabolism. Although hyperglycemia is associated with a variety of adverse outcomes frequently described in this population, evidence for causality is lacking. Variations in definitions and treatment approaches have further complicated the understanding and implications of hyperglycemia on the immediate and long-term effects in preterm newborns. In this review, we describe the relationship between hyperglycemia and organ development, outcomes, treatment options, and potential gaps in knowledge that need further research. IMPACT: Hyperglycemia is common and less well described than hypoglycemia in extremely preterm newborns. Hyperglycemia can be attributed to immaturity in several cellular pathways involved in glucose metabolism in this age group. Hyperglycemia has been shown to be associated with a variety of adverse outcomes frequently described in this population; however, evidence for causality is lacking. Variations in definitions and treatment approaches have complicated the understanding and the implications of hyperglycemia on the immediate and long-term effects outcomes. This review describes the relationship between hyperglycemia and organ development, outcomes, treatment options, and potential gaps in knowledge that need further research.

Outcomes of very preterm infants with hyperglycaemia treated with insulin: A systematic review and meta-analysis

AIM

To study the outcomes of very preterm infants with hyperglycaemia treated with Insulin.

METHODS

This is a systematic review of randomised controlled trials (RCTs) and observational studies. PubMed, Medline, EMBASE, Cochrane Library, EMCARE and MedNar databases were searched in May 2022. Data were pooled separately for adjusted and unadjusted odds ratios (ORs) using random-effects model.

MAIN OUTCOME MEASURES

Mortality and morbidities (e.g. Necrotising enterocolitis [NEC], retinopathy of prematurity [ROP]) in very preterm (<32 weeks) or very low birth weight infants (<1500 g) after treatment of hyperglycaemia with insulin.

RESULTS

Sixteen studies with data from 5482 infants were included. Meta-analysis of unadjusted ORs from cohort studies showed that insulin treatment was significantly associated with increased mortality [OR 2.98 CI (1.03 to 8.58)], severe ROP [OR 2.23 CI (1.34 to 3.72)] and NEC [OR 2.19 CI (1.11 to 4)]. However, pooling of adjusted ORs did not show significant associations for any outcomes. The only included RCT found better weight gain in the insulin group, but no effect on mortality or morbidities. Certainty of evidence was 'Low' or 'Very low'.

CONCLUSION

Very low certainty evidence suggests that Insulin therapy may not improve outcomes of very preterm infants with hyperglycaemia.

Outcomes of very preterm infants with neonatal hyperglycaemia: a systematic review and meta-analysis

OBJECTIVE

To explore the association between hyperglycaemia and adverse outcomes in very preterm infants.

DESIGN

Systematic review and meta-analysis. Data were pooled separately for adjusted and unadjusted odds ratios (ORs) using random-effects model. Subgroup analysis was conducted based on study design (cohort and case control).

MAIN OUTCOME MEASURES

Association between hyperglycaemia in preterm neonates (<32 weeks or <1500 g) and mortality and morbidities.

FINDINGS

Forty-six studies (30 cohort and 16 case control) with data from 34 527 infants were included. Meta-analysis of unadjusted ORs from cohort studies found hyperglycaemia to be significantly associated with mortality, any-grade intraventricular haemorrhage (IVH), severe IVH, any-stage retinopathy of prematurity (ROP), severe ROP, sepsis, chronic lung disease and disability. However, pooling of adjusted ORs found significant associations only for mortality (adjusted OR (CI): 2.37 (1.40 to 4.01); I²: 36%; 6 studies), 'Any grade IVH' (adjusted OR (CI): 2.60 (1.09 to 6.20); I²: 0%; 2 studies) and 'Any stage ROP' (adjusted OR (CI): 3.70 (1.55 to 8.84); I²: 0%; 2 studies). Meta-regression analysis found glucose levels >10 mmol/L to be associated with increased odds of mortality compared with <10 mmol/L. Pooled analysis from case-control studies were similar to cohort studies for most outcomes but limited by small sample size. Longer duration of hyperglycaemia was associated with adverse outcomes. GRADE of evidence was 'Low' or 'Very low'.

CONCLUSION

Hyperglycaemia in very preterm infants is associated with higher odds of mortality, any-grade IVH and any-stage ROP. A limitation was lack of availability of adjusted ORs from many of the included studies.

PROSPERO REGISTRATION NUMBER

CRD42020193016.

Strict glycaemic control in very low birthweight infants using a continuous glucose monitoring system: a randomised controlled trial

OBJECTIVE

To evaluate the efficacy of a strict glycaemic control protocol using a continuous glucose monitoring (CGM) in infants at high risk of dysglycaemia with the aim of reducing the number of dysglycaemic episodes.

DESIGN

Randomised controlled trial.

SETTING

Neonatal intensive care unit, Fondazione Policlinico Universitario Agostino Gemelli, IRCCS, Rome.

PATIENTS

All infants <1500 g fed on parental nutrition (PN) since birth were eligible. A total of 63 infants were eligible and 48 were randomised.

INTERVENTION

All participants wore a CGM sensor and were randomised in two arms with alarms set at different cut-off values (2.61-10 mmol/L (47-180 mg/dL) vs 3.44-7.78 mmol/L (62-140 mg/dL)), representing the operative threshold requiring modulation of glucose infusion rate according to an innovative protocol.

MAIN OUTCOME MEASURES

The primary outcome was the number of severe dysglycaemic episodes (<2.61 mmol/L (47 mg/dL) or >10 mmol/L (180 mg/dL)) in the intervention group versus the control group, during the monitoring time.

RESULTS

We enrolled 47 infants, with similar characteristics between the two arms. The number of dysglycaemic episodes and of infants with at least one episode of dysglycaemia was significantly lower in the intervention group (strict group): respectively, 1 (IQR 0-2) vs 3 (IQR 1-7); (p=0.005) and 12 (52%) vs 20 (83%); p=0.047. Infants managed using the strict protocol had a higher probability of having normal glycaemic values: relative risk 2.87 (95% CI 1.1 to 7.3). They spent more time in euglycaemia: 100% (IQR 97-100) vs 98% (IQR 94-99), p=0.036. The number needed to treat to avoid dysglycaemia episodes is 3.2 (95% CI 1.8 to 16.6).

CONCLUSION

We provide evidence that CGM, combined with a protocol for adjusting glucose infusion, can effectively reduce the episodes of dysglycaemia and increase the percentage of time spent in euglycaemia in very low birthweight infants receiving PN in the first week of life.

Perinatal complications and maximising lamb survival in an adolescent paradigm characterised by premature delivery and low birthweight

The competition for nutrients in overnourished and still-growing adolescent sheep negatively impacts gestation length, colostrum supply and lamb birthweight, all of which may affect neonatal morbidity and survival to weaning. Herein perinatal complications and the requirement for supplementary feeding were analysed in relation to gestational-intake, and the degree of premature delivery and prenatal growth-restriction exhibited. Pregnancies were established by embryo transfer and the mean/standard deviation (SD) gestation length and birthweight of the optimally-fed control group (n = 100) was used to define early delivery and reduced birthweight categories (1.5 and 3.0 SDs below the control mean for each aspect). Control lambs were largely delivered at term (94%), and had a normal birthweight (92%), while very preterm (≤139days, 18.5%) and preterm delivery (140-142days, 54.8%), extremely low birthweight (ELBW; females ≤2838g and males ≤3216g, 21.1%) and low birthweight (LBW; females 2839 to ≤4001g and males 3217 to ≤4372g, 32.2%), were common in the overnourished group (n = 270, P<0.001). Accordingly, overnourished dams were more likely to lamb without assistance while the incidence of major dystocia was greater in controls. Initial lamb vigour at birth was independent of gestational-intake, delivery or birthweight category but both ELBW and very premature lambs required more assistance with feeding in the first 24h postnatal, primarily reflecting low colostrum availability. Indeed, relative to normal, ELBW lambs had a greater risk of experiencing mismothering, and enhanced likelihood of requiring supplementary feeding throughout the neonatal period (P<0.001). ELBW lambs also had a greater possibility of respiratory issues at birth (P<0.01) and renal complications (P<0.001), while very preterm delivery was associated with an increased risk of gastrointestinal tract problems (P<0.01). In spite of these complications, all-cause mortality was low (5.4%) suggesting that our proactive neonatal care regime can overcome many of the issues associated with extreme prematurity and low birthweight.

Hyperglycemia in Extremely Preterm Infants

Hyperglycemia after birth is common in extremely preterm infants (<28 weeks of gestation). Lower gestational age, lower birthweight, presence of severe illness, and higher parenteral glucose intake increase the risk for hyperglycemia, while provision of higher amounts of amino acids and lipids in parenteral nutrition and early initiation and faster achievement of full enteral feeding decrease the risk. Hyperglycemia is associated with increased mortality and morbidity in the neonatal period. Limited data show an association with long-term adverse effects on growth, neurodevelopment, and cardiovascular and metabolic health. Lowering the glucose infusion rate and administration of insulin are the 2 treatment options. Lowering the glucose infusion could lead to calorie deficits and long-term adverse effects on growth and neurodevelopment. Conversely, insulin use increases the risk for hypoglycemia and requires close blood glucose monitoring and frequent adjustments to glucose infusion and insulin dosage. Randomized trials of varying strategies of nutrient provision and/or insulin therapy and long-term follow-up are needed to improve clinical care and overall health of extremely preterm infants with hyperglycemia.

Feasibility of automated insulin delivery guided by continuous glucose monitoring in preterm infants

OBJECTIVE

Closed-loop systems have been used to optimise insulin delivery in children with diabetes, but they have not been tested in neonatal intensive care. Extremely preterm infants are prone to hyperglycaemia and hypoglycaemia; both of which have been associated with adverse outcomes. Insulin sensitivity is notoriously variable in these babies and glucose control is time-consuming, with management requiring frequent changes of dextrose-containing fluids and careful monitoring of insulin treatment. We aimed to evaluate the feasibility of closed-loop management of glucose control in these infants.

DESIGN AND SETTING

Single-centre feasibility study with a randomised parallel design in a neonatal intensive care unit. Eligibility criteria included birth weight <1200 g and <48 hours of age. All infants had subcutaneous continuous glucose monitoring for the first week of life, with those in the intervention group receiving closed-loop insulin delivery in a prespecified window, between 48 and 72 hours of age during which time the primary outcome was percentage of time in target (sensor glucose 4-8 mmol/L).

RESULTS

The mean (SD) gestational age and birth weight of intervention and control study arms were 27.0 (2.4) weeks, 962 (164) g and 27.5 (2.8) weeks, 823 (282) g, respectively, and were not significantly different. The time in target was dramatically increased from median (IQR) 26% (6-64) with paper guidance to 91% (78-99) during closed loop (p<0.001). There were no serious adverse events and no difference in total insulin infused.

CONCLUSIONS

Closed-loop glucose control based on subcutaneous glucose measurements appears feasible as a potential method of optimising glucose control in extremely preterm infants.

Effects of preterm birth induced with or without exogenous glucocorticoids on the ovine glucose-insulin axis

Antenatal exogenous glucocorticoids (ANG) are standard management for women at risk of preterm birth but are reputed to impair glucose tolerance in preterm offspring. We compared lambs born preterm (137 days gestation) following labour induced with exogenous glucocorticoids (G-Prem, glucocorticoid-induced preterm group), or with a progesterone synthesis inhibitor (NG-Prem, non-glucocorticoid-induced preterm group), with term-born lambs (Term; 149 days). We assessed glucose tolerance, insulin secretion and sensitivity at 4 and 10 months n = 11-14/group) and pancreatic and hepatic gene and protein expression at 4 weeks post-term (4 weeks; n = 6/group) and 12 months (12 months; n = 12-13/group). NG-Prem had higher plasma glucose concentrations than G-Prem, but not Term, at 4 months (Mean[SEM] mM: NG-Prem = 4.1[0.1]; G-Prem = 3.4[0.1]; Term = 3.7[0.1]; p = 0.003) and 10 months (NG-Prem = 3.9[0.1]; G-Prem = 3.5[0.1]; Term = 3.7[0.1]; p = 0.01). Insulin sensitivity decreased from 4 to 10 months, in NG-Prem but not in Term (Mean[SEM] µmol·ml-1·kg-1·min-1·ng-1, 4 vs. 10 months: NG-Prem = 18.7[2.5] vs. 9.5[1.5], p < 0.01; Term: 12.1[2.8] vs. 10.4[1.5], p = 0.44). At 12 months, β-cell mass in NG-Prem was reduced by 30% vs. G-Prem (p < 0.01) and 75% vs. Term (p < 0.01) and was accompanied by an increased β-cell apoptosis: proliferation ratio at 12 months. At 12 months, pancreatic glucokinase, igf2 and insulin mRNA levels were reduced 21%-71% in NG-Prem vs. G-Prem and 42%-80% vs. Term. Hepatic glut2 mRNA levels in NG-Prem were 250% of those in G-Prem and Term. Thus, induction of preterm birth without exogenous glucocorticoids more adversely affected pancreas and liver than induction with exogenous glucocorticoids. These findings do not support that ANG lead to long-term adverse metabolic effects, but support an effect of preterm birth itself.

Real time continuous glucose monitoring in neonatal intensive care

Hypoglycaemia and hyperglycaemia are common in infants requiring intensive care and are associated with worse clinical outcomes. However, glucose levels are taken infrequently, and there remains controversy regarding optimal management. In adults and children continuous glucose monitoring (CGM) is now established as an important adjunct to caring for patients at risk from dysglycaemia. This technology is also increasingly providing insights into glucose regulation in the newborn, demonstrating significant periods of clinically silent hypoglycaemia and hyperglycaemia. This baseline data will be important to allow the significance of glucose dysregulation on long-term outcomes to be assessed. Small studies have also shown the potential for CGM to safely support targeting of glucose control in preterm infants, and a large multicentre trial is ongoing. Current technology is not specifically designed for use in NICU, but with rapid technological developments, CGM holds promise for the future care of babies in NICU.

Early-Stage Translational Research in Perinatal Medicine

BACKGROUND

Pre-clinical research, which encompasses studies in animals and in the laboratory, has made significant contributions to the improvement of neonatal outcomes.

METHODS

Here, we describe examples of how pre-clinical research can be the starting point on the journey to the development of new interventions to improve neonatal care and outcomes and discuss recent progress in ensuring methodological and ethical rigour in pre-clinical research involving animal models.

RESULTS

Studies in pregnant sheep led to the serendipitous discovery that preterm lambs born after exogenous corticosteroid exposure were able to aerate their lungs. Subsequent clinical trials confirmed that antenatal corticosteroids given to women at risk of preterm delivery substantially reduce mortality and morbidity in babies born preterm. Animal research also contributed to discoveries in the mechanism of brain injury after hypoxic ischaemic encephalopathy, leading to the use of therapeutic hypothermia as an effective treatment. However, animals are sentient creatures and there are significant ethical concerns with their use in studies to benefit human health. Mandated institutional animal research ethics committees ensure adherence to ethical requirements. To provide high-quality data which can be translated into clinical research, pre-clinical research needs to follow rigorous standards of study design and reporting. The ARRIVE guidelines provide guidance for pre-clinical research similar to that provided in the CONSORT guidelines for clinical trials and are gaining acceptance among researchers and journal editors.

CONCLUSION

Improved scientific rigour in the use of animal research will increase the likelihood that pre-clinical research will continue to translate into improved neonatal outcomes.

Impact of prematurity for pancreatic islet and beta-cell development

As increasing numbers of babies born preterm survive into adulthood, it is becoming clear that, in addition to the well-described risks of neurodevelopmental sequelae, there also are increased risks for non-communicable diseases, including diabetes. Epidemiological studies indicate that risks are increased even for birth at late preterm and early term gestations and for both type 1 and type 2 diabetes. Thus, factors related to preterm birth likely affect development of the fetal and neonatal beta-cell in addition to effects on peripheral insulin sensitivity. These factors could operate prior to preterm birth and be related to the underlying cause of preterm birth, to the event of being born preterm itself, to the postnatal care of the preterm neonate or to a combination of these exposures. Experimental evidence indicates that factors may be operating during all these critical periods to contribute to altered development of beta-cell mass in those born preterm. Greater understanding of how these factors impact upon development of the pancreas may lead to interventions or management approaches that mitigate the increased risk of later diabetes.

Relationships Between Early Nutrition and Blood Glucose Concentrations in Very Preterm Infants

OBJECTIVES

The aim of the study was to determine whether changes to early nutrition are associated with levels of glycemia in very preterm infants.

METHODS

A retrospective, observational study of infants <1500 g or <30 weeks' gestation admitted to Neonatal Intensive Care, National Women's Hospital, New Zealand, before (Old Protocol) and after (New Protocol) a change in nutritional protocol. Nutritional intakes were calculated and averaged by day for postnatal days 1 to 7 (week 1) and 1 to 28 (month 1). Relationships between glycemia measures, macronutrient intakes, and achievement of 10% enteral feeds (≥10% total intake) were explored using logistic regression.

RESULTS

Old Protocol (n = 190) and New Protocol (n = 267) groups had similar baseline characteristics. In week 1, New Protocol infants received more protein, less fat, and carbohydrate, had lower mean blood glucose concentrations (BGCs) (mean ± SD 4.9 ± 1.2 vs 5.6 ± 1.4 mmoll/L, P < 0.0001), less hyperglycemia (BGC > 8.5 mmol/L, 71 [27%] vs 80 [42%], P = 0.0005), but similar hypoglycemia (BGC < 2.6). In month 1, New Protocol infants also had less hyperglycemia (105 [39%] vs 96 [51%], P = 0.02) and lower mean BGC (5.0 ± 1.1 vs 5.5 ± 1.1 mmol/L, P < 0.0001), but insulin usage was similar. After adjustment for birth weight z score and gestational age, hyperglycemia was significantly associated with week 1 intakes (g · kg · day) of protein (odds ratio [95% confidence intervals] 0.47 [0.23-0.79], P = 0.004), fat (0.54 [0.40-0.74], P < 0.0001), and carbohydrate (1.25 [1.09-1.44], P < 0.0001). These relationships were similar for month 1. Each additional day to achieve 10% enteral feeds was associated with increased odds of hypoglycemia (1.09 [1.00-1.18], P = 0.04) and hyperglycemia (1.16 [1.06-1.28], P = 0.002).

CONCLUSIONS

In very preterm infants, macronutrient balance and small, early enteral feeds may assist glycemic control.

Continuous glucose monitoring in neonates: a review

Continuous glucose monitoring (CGM) is well established in the management of diabetes mellitus, but its role in neonatal glycaemic control is less clear. CGM has provided important insights about neonatal glucose metabolism, and there is increasing interest in its clinical use, particularly in preterm neonates and in those in whom glucose control is difficult. Neonatal glucose instability, including hypoglycaemia and hyperglycaemia, has been associated with poorer neurodevelopment, and CGM offers the possibility of adjusting treatment in real time to account for individual metabolic requirements while reducing the number of blood tests required, potentially improving long-term outcomes. However, current devices are optimised for use at relatively high glucose concentrations, and several technical issues need to be resolved before real-time CGM can be recommended for routine neonatal care. These include: 1) limited point accuracy, especially at low or rapidly changing glucose concentrations; 2) calibration methods that are designed for higher glucose concentrations of children and adults, and not for neonates; 3) sensor drift, which is under-recognised; and 4) the need for dynamic and integrated metrics that can be related to long-term neurodevelopmental outcomes. CGM remains an important tool for retrospective investigation of neonatal glycaemia and the effect of different treatments on glucose metabolism. However, at present CGM should be limited to research studies, and should only be introduced into routine clinical care once benefit is demonstrated in randomised trials.

Relationship between Measures of Neonatal Glycemia, Neonatal Illness, and 2-Year Outcomes in Very Preterm Infants

OBJECTIVES

To investigate relationships between early neonatal glycemia, neonatal characteristics, neonatal illness, and developmental outcomes in very preterm infants.

STUDY DESIGN

A retrospective, observational cohort study of 443 infants born weighing <1500 g or <30 weeks of gestation, and admitted within 24 hours to National Women's Hospital, Auckland, New Zealand. Glucose variability was defined as the standard deviation around the mean after log transformation of all blood glucose concentrations. Absolute glycemic excursions in the first week were used to divide the infants into 4 groups: normoglycemic; hypoglycemic; hyperglycemic, and unstable.

RESULTS

Compared with normoglycemic infants, hypoglycemic and unstable infants had lower birth weight z-scores, and hyperglycemic and unstable infants were of lower birth weight. Hypoglycemic infants had similar outcomes to normoglycemic infants. Hyperglycemic and unstable infants were less likely to survive without neonatal morbidity and less likely to survive without neurodevelopmental impairment at 2 years of age. Higher mean blood glucose concentration was seen in the hyperglycemic and unstable groups, and was associated with worse neonatal and 2-year outcomes. Greater glucose variability was seen in the hypoglycemic and unstable groups, and was associated with worse neonatal illness but not outcome at 2 years. No associations between measures of neonatal glycemia and neonatal or 2-year outcomes remained after correction for gestation, birth weight z-score, and socioeconomic status.

CONCLUSIONS

In very preterm infants, measures of neonatal glycemia are markers of gestational age and intrauterine growth, and are not independent predictors of neonatal illness or outcomes at 2 years of age.

Advances in nutrition of the newborn infant

Nutrition of newborn infants, particularly of those born preterm, has advanced substantially in recent years. Extremely preterm infants have high nutrient demands that are challenging to meet, such that growth faltering is common. Inadequate growth is associated with poor neurodevelopmental outcomes, and although improved early growth is associated with better cognitive outcomes, there might be a trade-off in terms of worse metabolic outcomes, although the contribution of early nutrition to these associations is not established. New developments include recommendations to increase protein supply, improve formulations of parenteral lipids, and provide mineral supplements while encouraging human milk feeding. However, high quality evidence of the risks and benefits of these developments is lacking. Clinical trials are also needed to assess the effect on preterm infants of experiencing the smell and taste of milk, to determine whether boys and girls should be fed differently, and to test effects of insulin and IGF-1 supplements on growth and developmental outcomes. Moderate-to-late preterm infants have neonatal nutritional challenges that are similar to those infants born at earlier gestations, but even less high quality evidence exists upon which to base clinical decisions. The focus of research in nutrition of infants born at term is largely directed at new formula products that will improve cognitive and metabolic outcomes. Providing the most effective nutrition to preterm infants should be prioritised as an important focus of neonatal care research to improve long-term metabolic and developmental outcomes.

Neonatal milk supplementation in lambs has persistent effects on growth and metabolic function that differ by sex and gestational age

The perinatal environment has a major influence on long-term health and disease risk. Preterm birth alters early-life environment and is associated with altered metabolic function in adulthood. Whether preterm birthper seor the early nutritional interventions used to support growth in preterm infants underpins this association is unknown. Lambs born preterm, following dexamethasone induction of labour, or spontaneously at term were randomised to receive nutrient supplementation, analogous to the milk fortifier used clinically or water as a control for the first 2 weeks after birth. Thereafter, nutrition was not different between groups. Growth was monitored, and the glucose–insulin axis function was assessed in juvenile (4 months) and adult life (14 months). Early nutrition influenced adult metabolic function and body composition to a greater extent than preterm birth. In supplemented females, arginine-stimulated insulin secretion was increased in preterm but reduced in term-born juveniles compared with controls (repeated-measures ANOVAP<0·01). In supplemented preterm males, adult weight, ponderal index (PI) and fasting insulin concentrations were elevated compared with preterm controls (weight, 75 (sem3)v. 69 (sem2) kg; PI, 48·0 (sem2·1)v. 43·7 (sem1·7) kg/m3; fasting insulin, 0·19 (sem0·02)v. 0·10 (sem0·02) ng/ml). Conversely, supplemented term-born males had reduced adult weight, PI and fasting insulin concentrations compared with term-born controls (weight, 64 (sem2)v. 70 (sem2) kg; PI, 44·4 (sem1·8)v. 48·2 (sem1·7) kg/m3; fasting insulin, 0·09 (sem0·02)v. 0·14 (sem0·02) ng/ml; all group×supplement interactionsP<0·05). Adult metabolic health may reflect both gestational age at birth and early nutrition. Human studies are urgently needed to investigate the adult sex-specific health implications of neonatal nutritional strategies.

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.