In the past two years the international consensus about HbA1c targets (long-term blood glucose levels) for children has lowered. Until the introduction of the newer insulins the target HbA1c for children was considerably higher than for adults.
“In children’s diabetes we used to have age-banded targets and we used to permit higher A1c in younger children. We did that because we didn’t want young children to run the significant risk of low blood sugars. That was because in the very chaotic life of the child under five years old, it’s very difficult to manage insulin and diabetes and food intake,” Professor Clodagh O’Gorman, Consultant Paediatrician, University Hospital Limerick, told the recent Diabetes Ireland National Spring Meeting in Tralee.
The target HbA1c for children used to become lower as they got older and could take part in planning their lives in terms of activities and food. “The very young child often doesn’t recognise the symptoms of a low, so the low can become very significant before it’s identified. So we used to have agebanded targets for HbA1c.
But about two years ago, internationally the consensus became that the target A1c for all children attending a paediatric clinic would be less than 58mmol/mol (7.5%),” said Professor O’Gorman.
Lower A1c reduces kids’ complications
This new target came about following the Diabetes Control of Complications Trial (DCCT) and the later Epidemiology of Diabetes Interventions and Complications (EDIC) study. These studies showed that lowering the HbA1c in young children from previous higher targets, reduced the long-term complications that these children with diabetes developed. The trials included two groups of children.One group received very intensive management of their diabetes from their diabetes team. Their care included lots of:
• Contact with their diabetes team
• Advice about managing highs
• Advice about preventing highs
• Advice about preventing lows.
The other group just received the traditional routine care of their diabetes.
DCCT followed the two groups for a number of years. It became very clear that those who received the intensive treatment had a lower HbA1c than those receiving routine care. But the most important finding was that they also had fewer complications related to their:
Some years later the EDIC trial got back in contact with those who had been in the DCCT trial. At this stage the children had now grown up. The researchers didn’t offer any of the people they studied different care. They just collected data on them and assessed their health.
In the later EDIC trial all of the people in the study had a similar HbA1c. However, very significantly, those who as children had received intense management and lower HbA1c still had fewer complications than the others.
“You struggle for a good HbA1c not so you have a good number in clinic, not so that the team smiles at you when you walk out the door, but because you know that it decreases the risk of your complications in the future,” said Professor O’Gorman.
“The teenage years are tough years. Most people go through a phase in their teenage years when they’ve a high A1c. But if you can get back on track after that phase, you should be able to reduce that HbA1c again and you should be able to reduce your risk of complications in the future,” said Professor O’Gorman.
Even kids should have HbA1c under 58mmol/mol (7.5%)
“Now we think the ideal HbA1c is less than 58mmol/mol (7.5%) for all children.
And then when you go to your adult clinic it’s less than 48mmol/mol (6.5%).
And there are other times in your life, like if a young woman is going to try to become pregnant, she should aim for less than 48mmol/mol (6.5%),” said Professor O’Gorman.
This 58mmol/mol is not a number plucked from the skies. The information provided by the DCCT and EDIC studies were closely examined to identify at exactly what A1c did the risk of complications begin to increase.
The other side is that of course it is equally risky to have an HbA1c that is too low.
How HbA1c is measured
Your HbA1c gives an average of your blood glucose levels, but it is not a mathematical average. So if you write all your blood glucose level readings in a notebook over a couple of months, you cannot use those figures to accurately show your HbA1c. Of course, the HbA1c does not take account of how many high and low blood glucose readings you are having. “So if you have lots and lots of lows you might turn up in clinic and look like you’ve got a great A1c, but at what expense?” said Professor O’Gorman.
All these lows can mean that you have a half-hour a day when you’re feeling terrible with your hypo and having to treat it. “That’s not the context that we want a good A1c in. So ideally we want a good A1c without lots of lows. And the other side of that is if you’re having lots of lows and you have an average to poor A1c, it probably means you’re having lots of highs to counterbalance them. This means you’ve got these periods in the day where you’re going from a low sugar to a high sugar to a low sugar, so we call that glucose variability ‘glucose excursion’. And that’s not good for you either,” said Professor O’Gorman.
This means that your child’s diabetes team aims for an HbA1c of less than 58mmol/mol (7.5%), but without significant hypos and significant glucose excursions (rapid changes in blood glucose levels).
New insulins make new targets possible
The results of the DCCT and EDIC trials were at first difficult for diabetes teams and people with diabetes to put into practice. But since then there have been rapid developments into different types of insulins to suit different scenarios and times of day. These new insulins make it much more feasible to achieve the new target HbA1c level in children.
Nowadays there are basal-bolus insulins regimes and insulin pumps. ‘Basal’ insulin is a long-acting insulin that provides a steady dose of insulin over 24 hours. The ‘bolus’ insulins are fast-acting and their effect does not last as long. You can tailor these new insulins to your child’s activity level and to their food intake.
“We used to prescribe insulin and you had to work your life around it.
But now hopefully when you present with diabetes you tell us about your life and we try to find a regime that’s going to fit into your life as reasonably smoothly as it can.
“For those of us who work in diabetes, we hope that if we look at this generation who is being managed using our current targets for A1c and our currently available insulin, that if we fast forward into the future we’ll see fewer complications and we’ll see them occurring at a later age,”said Professor O’Gorman.
Article by Sheila O’Kelly, Editor of Diabetes Ireland.