Background Reliable, painless glucose surveillance is critical during the early neonatal fall in plasma glucose levels. However, existing continuous glucose monitors are invasive and expensive. We evaluated a non-invasive method for estimating blood glucose levels from the phase delay (Δθ) between oxy- and deoxyhemoglobin waveforms, expressed as a metabolic index (MI). Methods Thirty-eight term neonates were enrolled on postnatal day 2, and 30 recordings satisfied the predefined signal quality criteria. Neonatal pulse oximetry probes captured 5-min photoplethysmography traces, from which stable 15–60-s epochs were extracted. The α-corrected MI for each infant was correlated with plasma glucose measured on an ABL90 FLEX analyzer. Glycemic slopes were compared with published adult data using ANCOVA. Results The α-corrected MI showed a significant positive correlation with plasma glucose (R2 = 0.51, r = 0.71; p < 0.01). Linear regression for neonates was MI = 0.17 × glucose – 6.78. Both slope and intercept differed from adult values (p < 0.05), indicating age-dependent modulation of the Δθ–glucose relationship. Conclusions Phase-delay analysis using standard pulse oximetry provides a promising approach for continuous glucose estimation in term neonates. Age-specific calibration is required before clinical deployment; however, the technique’s low cost and noninvasiveness potentiate universal bedside hypoglycemia surveillance. Impact <UnorderedList Mark="Bullet"> <ItemContent> Key message: Non-invasive glucose monitoring using the phase delay between oxy- and deoxyhemoglobin waveforms obtained from a pulse oximetry probe shows a significant correlation with blood glucose levels in term neonates. </ItemContent> <ItemContent> Literature contribution: This study demonstrates that the metabolic index derived from hemoglobin phase delays differs between neonates and adults, suggesting the need for age-specific calibration. </ItemContent> <ItemContent> Clinical impact: This low-cost technique may enable continuous bedside glucose surveillance in neonates without repeated blood sampling. </ItemContent> </UnorderedList>

Neonatal blood glucose monitoring using glucose estimation by phase delay between oxy- and deoxyhemoglobin

期刊论文
发表日期：

2026年6月23日

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Tomoaki Kusaka,
Kosuke Koyano,
Tomoya Nakazawa,
Yuta Noguchi,
Yuta Shinabe,
Hirosuke Morita,
Katsufumi Nishioka,
Kota Inoue,
Aya Morimoto,
Shinji Nakamura,
Sonoko Kondo,
Yukihiko Konishi,
Keiji Morishita,
Takashi Kusaka

摘要

Background

Reliable, painless glucose surveillance is critical during the early neonatal fall in plasma glucose levels. However, existing continuous glucose monitors are invasive and expensive. We evaluated a non-invasive method for estimating blood glucose levels from the phase delay (Δθ) between oxy- and deoxyhemoglobin waveforms, expressed as a metabolic index (MI).

Methods

Thirty-eight term neonates were enrolled on postnatal day 2, and 30 recordings satisfied the predefined signal quality criteria. Neonatal pulse oximetry probes captured 5-min photoplethysmography traces, from which stable 15–60-s epochs were extracted. The α-corrected MI for each infant was correlated with plasma glucose measured on an ABL90 FLEX analyzer. Glycemic slopes were compared with published adult data using ANCOVA.

Results

The α-corrected MI showed a significant positive correlation with plasma glucose (R² = 0.51, r = 0.71; p < 0.01). Linear regression for neonates was MI = 0.17 × glucose – 6.78. Both slope and intercept differed from adult values (p < 0.05), indicating age-dependent modulation of the Δθ–glucose relationship.

Conclusions

Phase-delay analysis using standard pulse oximetry provides a promising approach for continuous glucose estimation in term neonates. Age-specific calibration is required before clinical deployment; however, the technique’s low cost and noninvasiveness potentiate universal bedside hypoglycemia surveillance.

Impact

Key message: Non-invasive glucose monitoring using the phase delay between oxy- and deoxyhemoglobin waveforms obtained from a pulse oximetry probe shows a significant correlation with blood glucose levels in term neonates.

Literature contribution: This study demonstrates that the metabolic index derived from hemoglobin phase delays differs between neonates and adults, suggesting the need for age-specific calibration.

Clinical impact: This low-cost technique may enable continuous bedside glucose surveillance in neonates without repeated blood sampling.