Can a Baby's Blood Sugar in the First Days of Life Shape How They Grow?

A 2026 Italian study followed very premature babies with a continuous glucose sensor and checked their development at one year

Researchers in Padova, Italy, gently placed a small glucose sensor on the leg of 60 very premature babies, tracked their blood sugar around the clock for the first days of life, and then measured how those children were developing at one year of age. They found that the premature babies were, on average, a little behind full-term babies in thinking, movement, and especially language — though most were still within the normal range — and, intriguingly, that babies whose blood sugar had stayed steadier tended to do better on tests of memory and language. This does not prove that steadier blood sugar causes better development, but it points to something families and doctors may one day be able to influence.

Why This Question Matters

Every parent of a baby in the neonatal intensive care unit (NICU) quickly learns that blood sugar is watched closely. Premature babies have tiny energy reserves and immature livers, so their blood sugar can swing too low or too high in the first days of life [1]. The brain runs almost entirely on glucose, so it is reasonable to worry that these swings might affect how the brain grows [2]. That worry is not new. Back in 1988, a landmark study reported that premature babies with repeated low blood sugar tended to have lower developmental scores later [3], and that finding shaped how NICUs have managed blood sugar ever since.

How Families and Doctors Used to Face This

Here is the surprising part: despite decades of careful blood-sugar management, doctors have never been certain how much those early glucose numbers really matter for a child's future. When scientists have gone back and studied it carefully, the results have disagreed with one another [4],[5]. One of the most careful studies ever done, following hundreds of at-risk newborns, found that babies whose low blood sugar was caught and treated developed just as well at two years as those who never had low sugar [6]. Another study focused on very premature babies also found no clear connection at two years [7]. So doctors have been in the awkward position of carefully managing a number without being sure what it means for the long run.

Two things made this an old question worth asking again. The first is a piece of technology borrowed from diabetes care: the continuous glucose monitor, or CGM. A traditional blood-sugar check is a single heel-prick giving a single number, hours apart — like glancing at a busy road once an hour and trying to describe the traffic. A CGM measures sugar continuously, catching the brief dips and spikes that spot checks miss, and revealing how steady or bumpy a baby's sugar is overall [4]. Earlier trials showed that CGM is safe for premature babies and helps keep their sugar in a healthy range more of the time [8],[9]. The second is a better toolkit for measuring a baby's development — not just the standard checklist, but sensitive computer-and-camera tasks that watch where a baby looks, revealing subtle differences in attention and memory that a checklist can miss [10].

What the Researchers Did

The study was part of a larger project called BabyGlucoLight at Padova University Hospital [11]. Very premature babies — born at 32 weeks of pregnancy or earlier, or weighing 1500 grams or less — had a sensor placed on the outer thigh within two days of birth and worn for about five days. To keep the baby comfortable during placement, the team used a pacifier and a few drops of sweet sucrose solution, a gentle and standard way to ease minor procedures [11].

At one year of age (adjusted for prematurity), each child came back for a check-up. They took a well-known developmental assessment called the Bayley Scales, which looks at thinking, language, movement, and social-emotional skills. They also did two playful eye-tracking activities: one measured how quickly and flexibly a baby shifts attention between pictures, and the other measured visual memory by seeing whether the baby noticed when one picture kept changing. For comparison, 31 full-term babies did the same activities. Sixty premature babies joined the study; 43 completed the one-year visit, with some unable to continue because of sensor problems, and, sadly, six babies who did not survive to follow-up [11].

What They Found

The premature babies scored a bit lower than the full-term babies across thinking, movement, and language, with the biggest difference in language — especially in the words babies were beginning to say [11]. It is worth stressing that most scores were still in the normal range; the difference was a gentle overall shift, not a sign that these children were destined for problems.

The eye-tracking activities showed something quieter but interesting. On average, the two groups looked fairly similar. But the premature babies were much more likely to become restless or distracted so that their trials could not be used — about half of the attention trials for premature babies could not be scored, compared with only a small fraction for full-term babies [11]. The researchers took this as a hint that very premature babies may have more fragile early attention, something that ordinary tests can easily overlook.

The headline finding came from looking within the premature group at their glucose sensor data. Overall, their blood sugar was quite well controlled — in the healthy range about 83% of the time [11]. Even so, the babies who had spent more time in that healthy range, and whose sugar had been steadier rather than bumpier, tended to do better on the memory task and on language [11]. In other words, it was not just about avoiding a single low reading; it was about the overall smoothness of the blood-sugar picture over those first days. This fits with a growing view among researchers that the whole pattern of blood sugar over time may matter more than any one number [12].

What This Means for Families and Their Baby's Care

If your baby was born prematurely, the most important and reassuring message from this study is that prematurity itself — not any single glucose reading — is the main reason for the small developmental differences seen here, and that those differences were modest. This study cannot tell you anything about how a particular baby will do based on their glucose chart. It looked at only 43 premature babies at one hospital, which is a small number, so its findings are an early clue, not a firm conclusion. The researchers themselves are careful to say so.

What families can take from it is encouragement that the careful attention NICU teams already pay to blood sugar is worthwhile, and that scientists are actively studying whether keeping blood sugar steadier could give premature babies an extra developmental edge. It is also a reminder that a normal score on a one-year check-up does not close the book: because language and attention differences can be subtle and can grow clearer with age, keeping up with developmental check-ups and asking for a speech or early-intervention referral if you have concerns is sensible and empowering, not alarmist.

One detail from the study is quietly reassuring on this point. The reason so many of the premature babies' eye-tracking trials could not be scored was often simply that the babies grew restless or looked away — the ordinary behaviour of a one-year-old who has had enough. That is not a sign of damage; it is a sign that these tests are demanding and that premature babies sometimes need a little more patience to show what they can do. Parents who have felt that a formal assessment did not capture their child at their best are often right, and it is completely appropriate to ask for a repeat visit on a better day, or to point out to the team the skills you see at home that did not appear in the testing room. Development is a story that unfolds over years, and a single chapter rarely tells the whole of it [11].

What Researchers Are Working On Next

The big unanswered question is whether deliberately keeping a premature baby's blood sugar steadier would actually improve development, or whether steadier sugar is simply a sign of a baby who was less sick to begin with [11]. Answering that will take larger studies across many hospitals, following children for longer — which is exactly what the BabyGlucoLight team is building toward, with further check-ups planned at two years [11]. Continuous glucose monitors are not yet part of routine newborn care, and blood-sugar targets today still rest on long-standing guidelines. But this study adds a hopeful thread to a decades-old puzzle [13]: the possibility that something as manageable as the steadiness of a baby's blood sugar, in just the first few days of life, might be one more way to help the smallest babies thrive.

References

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