HbA1c not accurate enough for pre-teens with type 1 diabetes

Posted on 01 August 2019

A group of children sitting on a rock

A study published in July’s Diabetes Care journal has shown that children with type 1 have highly variable blood glucose levels, particularly before puberty – and that these are not effectively captured by HbA1c measurements.

By using continuous glucose monitoring (CGM) devices to monitor blood glucose levels in children aged 8 to 17, the researchers showed that children who had not yet reached puberty had the highest variability in blood glucose levels and most extreme highs and lows. This was not always reflected in their HbA1c measurements.

This research shows how puberty can affect blood glucose levels – and highlights the need to move beyond HbA1c as a measure of how people with type 1 are managing with their condition.

It also provides evidence that children with type 1 could benefit from access to a CGM – increasing pressure on regulatory bodies to widen access to the technology for those who want and need it.

Why did they do this research?

Previous research has suggested that growth spurts and changes in hormone levels, both of which are common during puberty, can make managing blood glucose more challenging than usual.

The researchers wanted to see how blood glucose levels varied in children before, during and after puberty.

They also wanted to compare different ways of measuring glucose variability, as a better understanding of this could make it easier for people to manage their condition, and lead to fewer hypos and hypers.

What did they do?

The group recruited children aged 8 to 17 who had been diagnosed with type 1 for over a year. They then gave them a physical assessment to split them into groups according to whether they had gone through puberty.

All children were given a CGM for four weeks and the researchers looked at the variations in glucose levels over certain time periods. They also compared the different ways of measuring this variability – for example through real-time CGM and HbA1c.

What did they find?

Children who were going through puberty needed more insulin than children in the other groups. This supports past research showing that people can develop some resistance to insulin during puberty.

In addition, children who had not yet gone through puberty had the highest variation in their blood glucose levels, including the biggest drops in their levels overnight.

The researchers suggest that this could be due to younger children being more sensitive to insulin, as well as having more unpredictable eating and activity habits.

Somewhat understandably then, the researchers found that using HbA1c alone was an unreliable measure of blood glucose levels for all children, but especially the pre-puberty group.

In this group, even those that achieved their target HbA1c values actually had above-target average blood glucose levels when measured with CGM.

What does this mean for type 1?

By showing that HbA1c doesn’t effectively represent blood glucose levels in children, this study highlights the need for closer monitoring of blood glucose levels during this time. It also gives an insight into how puberty can affect blood glucose variability, enabling parents and caregivers of children with type 1 to have a greater understanding and awareness of this effect.

Importantly, the study provides evidence that children with type 1 could benefit from access to a CGM, particularly as they approach puberty.

At JDRF, we actively advocate and campaign for people with type 1 to be able to access the treatments that they want and need, and evidence like this is important in helping us to achieve this goal.

Read our position statement on HbA1c

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