First-week Hyperglycemia in Extremely Preterm Infants

In extremely preterm infants, does first-week neonatal hyperglycemia identify a group with different short-term respiratory and ophthalmologic outcomes? Investigators at a single NICU reported a retrospective cohort of 225 infants born at gestational age <28 weeks and admitted in 2018–2019, in which 58.2% met their exposure definition of hyperglycemia during the first postnatal week (peak blood glucose >8.3 mmol/L). The analysis used propensity-score matching and then compared matched groups on respiratory morbidity measures and severe retinopathy of prematurity (ROP), presenting results as associations rather than treatment effects. The stated comparison was outcomes among infants with versus without early hyperglycemia in this extremely preterm cohort.

Hyperglycemia was defined as any peak blood glucose value >8.3 mmol/L (>150 mg/dL) recorded during the first 7 postnatal days, with glucose measured in capillary or arterial whole blood using a point-of-care glucometer per a standardized unit protocol. The study drew data from electronic records and applied a 1:1 nearest-neighbor propensity-score matching approach without replacement (caliper width 0.1 of the logit of the propensity score). Matching yielded 109 infants: 55 in the hyperglycemia group and 54 controls, using baseline/perinatal factors including gestational age, birth weight, sex, antenatal steroid exposure, delivery-room intubation, and surfactant administration. The authors described matching as a method to balance measured perinatal characteristics between exposure groups before comparing outcomes.

In the matched analysis, the authors reported higher ventilator-associated pneumonia (VAP) incidence in the hyperglycemia group, estimating an incidence rate ratio of 6.2 (95% CI, 1.4–27.6). Infants with hyperglycemia also had a longer duration of invasive ventilation (19.8 ± 25.3 vs 8.9 ± 24.8 days); the paper reported a mean difference (MD) of −10.9 days (p=0.042), reflecting the subtraction order used in their analysis. Postnatal steroid exposure (administered beyond the first postnatal week and not described as a treatment for early hyperglycemia) was more frequent among infants with early hyperglycemia, with an odds ratio of 4.6 (95% CI, 1.6–14.4; p=0.040). For bronchopulmonary dysplasia, the authors described a trend toward more moderate-to-severe disease in the hyperglycemia group in the matched analysis (p=0.054). These findings were presented as associations observed after balancing measured perinatal factors.

For ophthalmologic outcomes, severe ROP occurred more often in the hyperglycemia group after matching (OR, 4.0; 95% CI, 1.0–15.5; p=0.032), which the authors highlighted as a persistent association alongside VAP. Mortality rates were reported as not significantly different between matched groups, while age at death among non-survivors was higher in the hyperglycemia group in the matched analysis (mean difference, −25.93 days; p=0.015). In discussion and conclusions, the authors framed early hyperglycemia as a clinically relevant early risk marker for short-term respiratory morbidity and severe ROP in extremely preterm infants, and they stated that prospective and interventional studies are needed to further evaluate these relationships. Their stated takeaway was that early dysglycemia may function as a clinically relevant early risk marker to help identify infants who may benefit from closer monitoring and targeted preventive strategies, rather than establishing causality.

Key Takeaways:

• In this single-center cohort (2018–2019) of 225 infants born at GA <28 weeks, 58.2% met the study’s definition of first-week hyperglycemia (peak blood glucose >8.3 mmol/L within 7 days).
• After propensity matching, early hyperglycemia was associated with more VAP, longer invasive ventilation, greater postnatal steroid exposure, and a reported trend toward more moderate-to-severe BPD.
• Severe ROP remained more frequent in the hyperglycemia group after matching, and the authors characterized early hyperglycemia as a clinically relevant early risk marker and stated that the findings justify further prospective and interventional studies.