Intraday glucose fluctuation is common in preterm infants receiving intermittent tube feeding

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.

Glucose variability in 6-12-month-old healthy infants

Background

Metabolic programming of glucose homeostasis in the first 1,000 days of life may impact lifelong metabolic and cardiovascular health. Continuous glucose monitoring (CGM) devices may help measure the impact of dietary intake on glucose rhythms and metabolism in infants during the complementary feeding period.

Objectives

Demonstrate the feasibility of CGM to measure and quantify glucose variability in response to infant feeding and to evaluate associations between macronutrient meal composition and glucose variability.

Methods

The "FreeStyle Libre Pro^®" device interstitial glucose meter was applied to the anterior thigh of 10 healthy 6-12-month-old infants. Parents recorded food intake, time of feeding, and used daily dairies to record sleep time and duration. Descriptive statistics were employed for food intake, sleep and key glycemic parameters over three full days. Mixed linear models were used to assess glycemic changes.

Results

Mid-day, afternoon, and evening feeds contained >30 g carbohydrate and induced higher 2-h iAUC (3.42, 3.41, and 3.50 mmol/L*h respectively) compared to early and mid-morning feedings with ≤25 g carbohydrates (iAUC 2.72 and 2.81 mmol/L*h, p < 0.05). Early morning and evening milk feedings contained approximately 9 g of fat and induced a longer time to reach maximal glucose value (Tmax; 75 and 68 min, respectively) compared to lower fat feedings (2.9-5.9 g; Tmax range: 34-60 min; p < 0.05). Incremental glucose value at time of food intake (C0) increased significantly from 0.24 ± 0.39 mM in early morning to 1.07 ± 0.57 mM in the evening (p < 0.05). Over the day, 70% of glucose values remained within the normal range (3.5-5.5 mmol/L), 10% were between 5.5-10 mmol/L, and 20% were < 3.5 mmol/L.

Conclusion

Our data support the feasibility of using CGM to measure glucose in 6-12-month-old infants. The observation of possible diurnal glucose variability and typical glucose values may have implications for future studies investigating metabolic adaptation to nutritional intake in early life.

Continuous Glucose Monitoring in Preterm Infants: The Role of Nutritional Management in Minimizing Glycemic Variability

Glycemic variability (GV) is common in preterm infants. In the premature population, GV is a risk factor for morbidity and mortality. Both hypo- and hyperglycemia can impair neurodevelopment. We investigated the impact of continuous versus intermittent tube enteral feeding on GV. In our prospective observational study, 20 preterm infants with a gestational age ≤ 34 weeks at either continuous or intermittent bolus full enteral feeding. For five days, continuous glucose monitoring (CGM) was utilized, which was achieved through the subcutaneous insertion of a sensor. A total of 27,532 measurements of blood glucose were taken. The mean amplitude of glycemic excursions did not differ between the two cohorts statistically. Continuous feeding resulted in higher positive values, increasing the risk of hypo- and hyperglycemia. Subjects who were small for their gestational age had a higher standard deviation during continuous feeding (p = 0.001). Data suggest that intermittent bolus nutrition is better for glycemic control than continuous nutrition. Nutritional management optimization of preterm infants appears to be critical for long-term health. In the future, CGM may provide a better understanding of the optimal glucose targets for various clinical conditions, allowing for a more personalized approach to management.

Gastrointestinal and feeding issues for infants <25 weeks of gestation

Appropriate nutrition is essential for optimal development and growth of preterm infants. Infants less than 25 weeks corrected gestational age are frequently the most difficult group for which to provide adequate nutrition due to minimal energy stores and high fluid losses. Nutrient delivery becomes an integral, but also very challenging part in their management. Early administration of intravenous nutrients provides a critical bridge to full enteral nutrition. However, enteral feeding is challenging due to immaturities of the intestinal tract, feeding intolerance and the risk of catastrophic gastrointestinal disease such as necrotizing enterocolitis (NEC). Decreased gastric acid production, increased gut permeability, reduced immunoglobulins, immature intestinal epithelia and a decreased mucin barrier all contribute to weakness to gastrointestinal insult. This review aims to illustrate the importance of enteral feeding and the common challenges and approaches in the nutrition of infants born at this age.

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.

Prematurity at less than 24 weeks of gestation is a risk for prolonged hyperglycemia in extremely low-birth weight infants

Hyperglycemia in extremely low-birth weight infants (ELBWIs) is frequently observed during the acute perinatal phase, (i.e., first 1-2 weeks postnatal period); however it can occasionally persists for >2 weeks, extending to the post-acute phase. Since such prolonged hyperglycemia (PH) is not typical for ELBWIs, the aim of the present study was to further understand the clinical details of PH. Twenty-five hyperglycemic ELBWIs born before 28 weeks of gestation from 2015 to 2018 were included in the study. Based on the duration of hyperglycemia, we separated the subjects into two groups: non-prolonged hyperglycemia (NPH) who achieved remission within ≤2 weeks [n = 18, median 3.0 (range, 2.0-4.0) days], and PH, whose hyperglycemia persisted for >2 weeks [n = 7, median 50.0 (range, 33.5-66.0) days]. Compared to the NPH group, glucose metabolism of the PH group was more deteriorate. The peak blood glucose level was significantly higher in the PH group [PH: median 472 mg/dL, NPH: median 275 mg/dL, p < 0.001], and a higher proportion of subjects in the PH group required insulin therapy [PH: 100% (7/7) vs. NPH: 22% (4/22)]. Multivariate analysis revealed that among perinatal factors, prematurity was the only independent risk factor for PH (glucocorticoid therapy: p = 0.884, gestational age: p = 0.006), with a cutoff of 23W4D determined by receiver operating characteristic analysis. Our data revealed distinctive clinical features of PH, suggesting a type different from the previously reported hyperglycemia in ELBWIs. Specifically, extreme prematurity, less than 24 weeks of gestation, is a risk for PH, and aggressive interventions, such as insulin would be required.

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.

Continuous feeding versus intermittent bolus feeding for premature infants with low birth weight: a meta-analysis of randomized controlled trials

Background/objectives

Clinical risks and advantages of both continuous feeding and intermittent feeding for preterm infants have been presented in previous studies. To determine the most appropriate feeding method for low-birth-weight infants, a meta-analysis was conducted.

Subjects/methods

Articles related to this topic were searched in PubMed, EMBASE, and Cochrane Library electronic database from the onset to May 2019. Heterogeneity analysis was performed with Chi-square and I² test. Pooled analysis was based on fixed effects model, if heterogeneity between the eligible studies was negligible (I² < 50%, P > 0.05). In contrast, a random effects model was carried out. The quality of including studies were evaluated by Cochrane assessment tool.

Results

A total of 1030 articles identified. Altogether, eight articles including 707 infants were included in final analysis based on eligibility criteria. In continuous feeding infants, time to achieving full feeds was longer (weight mean difference 0.98 (95% CI 0.26–1.71, P = 0.008) days) compared with intermittent feeding infants. Pooled analysis indicated there were no significant difference in other variables such as feeding intolerance, duration of hospitalization, days to regain birth weight, days to first successful oral feeding, duration of parenteral feeding, weight growth, length increment, head circumference growth, proven necrotizing enterocolitis, and probable necrotizing enterocolitis. In subgroup analysis for birth weight (<1000 g and >1000 g), we did not identify significant difference in time to full feeds, time to regain birth weight, and duration of hospitalization.

Conclusions

Intermittent feeding may be more beneficial for low-birth weight infants, However, well-designed studies and evidenced-based clinical practice are required to determine the most appropriate feeding method for premature infants with low birth weight.

Reliability of real-time continuous glucose monitoring in infants

BACKGROUND

Neonatal hypoglycemia is a common and treatable risk factor for neurological impairment. Real-time continuous glucose monitoring (RT-CGM) can show glucose concentration in real time. Using an RT-CGM alarm, physicians can be alerted and intervene in hypoglycemia. No reports, however, have evaluated the reliability of RT-CGM at low glucose levels in infants. This study therefore investigated the difference between blood glucose (BG) and RT-CGM sensor data at low glucose levels and assessed the optimum method of using a hypoglycemic alarm in infants.

METHODS

We enrolled infants whose glycemic management was difficult. We calculated the mean absolute difference (MAD) and mean absolute relative difference (MARD) between BG and RT-CGM sensor data. We compared the MAD and MARD between the low BG fluctuation and high BG fluctuation groups.

RESULTS

We used RT-CGM for 12 patients (29 times) and investigated 448 pairs of BG and RT-CGM sensor data. The MAD between these pairs was 9.3 ± 8.9 mg/dL, and the MARD was 11.5%. The MAD at low glucose was 7.7 ± 6.0 mg/dL, and the MARD was 16.2%. The MAD and MARD were 6.8 ± 5.4 mg/dL and 7.8% in the low fluctuation group and 10.1 ± 9.5 mg/dL and 12.7% in the high fluctuation group, respectively.

CONCLUSIONS

The difference between BG and RT-CGM sensor data changes with the degree of fluctuation in BG. When physicians set the hypoglycemic alarm, consideration of this difference and a change in the alarm setting according to the degree of fluctuation in BG may be useful.

Continuous glucose monitoring can disclose glucose fluctuation in advanced Parkinsonian syndromes

Continuous glucose monitoring (CGM) is a method to examine glucose concentration in subcutaneous interstitial fluid sequentially. CGM can disclose glucose fluctuation (GF), which can be unrecognized in routine blood tests. A limited number of studies suggest advanced Parkinsonian syndromes (PS) is at risk of GF, however, the report of CGM in PS is scarce. We performed CGM for 72 h in 11 nondiabetic patients with advanced PS. The etiology was Parkinson’s disease, multiple system atrophy, progressive supranuclear palsy, or dementia with Lewy bodies. All participants were bedridden, elderly (≥65 year-old), and receiving enteral nutrition. The retrospective data was obtained after the removal of CGM device. In the glucose concentration, 9 (81.8%) participants showed nocturnal decline (≤70 mg/dL; 4 of them reached recordable limit of 40 mg/dL), and 6 (54.5%) participants showed remarkable elevation (≥200 mg/dL) postprandially. In the majority, these abnormalities were difficult to predict from routine blood tests. Standard deviation and mean of sequential glucose concentration were higher than those in precedent reports of young or middle-aged healthy controls. CGM in nondiabetic and elderly patients with advanced PS can disclose GF, with features of nocturnal decline and/or postprandial remarkable elevation of glucose concentration. Owing to limitations such as small sample size, heterogeneity of etiology, and retrospectivity of CGM data, further investigations are required.

Fluctuation of blood glucose levels in an infant with an ileostomy on continuous glucose monitoring: A case report

Infants with an ileostomy can be at high risk of hypoglycemia because of inadequate nutritional intake; however, there are no reports investigating blood glucose (BG) in infants with ileostomy. We experienced a case of an extremely low birth weight infant who was born at 24 wk of gestation and weighted 623 g. He received an ileostomy because of an intestinal perforation. After the ileostomy, he had recurrent hypoglycemia. Continuous glucose monitoring showed fluctuation of BG levels (postprandial BG elevations and subsequent declines) and non-fasting hypoglycemia, which were undetectable with intermittent fasting BG measurement. The fluctuation of BG levels and non-fasting hypoglycemia improved after closure of the ileostomy. Patients with ileostomy may present with hypoglycemia that is undetectable with intermittent fasting BG measurement. In this case, continuous glucose monitoring was very useful for detecting fluctuation of BG levels and hypoglycemic episodes. Therefore, we recommend that continuous glucose monitoring be performed in infants with an ileostomy to confirm whether they have hypoglycemia or a fluctuation in BG levels. Further studies on the postprandial dynamics of various hormones in infants with ileostomy are required.

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.

Serial investigation of continuous glucose monitoring in a very low birth weight infant with transient late-onset hyperglycemia

Transient late-onset hyperglycemia was detected in a very low birth weight (VLBW) infant (gestational age 28 weeks, birth weight 1,082 g) by routine point-of-care glucose monitoring.　The infant had no clinical symptom.　Serial continuous glucose monitoring (CGM) was conducted for 3 days at 31, 35, and 39 weeks' post conceptual age.　The difference values between the maximum and minimum blood glucose levels during the interval from one enteral feeding to the next enteral feeding were 32.3±14.3 mg/dL, 47.5±22.9 mg/dL, and 27.5±12.9 mg/dL for the 1^st, 2^nd, and 3^rd CGM, respectively.　The serial change in the values was statistically significant (p<0.01).CGM is widely used as a routine clinical practice, which is true even in VLBW infants.　Hyperglycemic events detected by only once of CGM in otherwise healthy preterm infants have already been reported on larger numbers of patients.　To our knowledge, this is the first report that the change of glucose intolerance in a VLBW infant with transient late-onset hyperglycemia was investigated by serial CGM.