medwireNews: Children with islet autoantibodies are highly likely to progress to clinical diabetes within the next year if their glucose levels are hyperglycaemic for more than 10% of the time, show findings from the ASK study.

The 91 children in the study were aged between 1 and 17 years and had had been identified during population screening as having at least one islet autoantibody. Eighteen percent of these children progressed to clinical diabetes, after a median interval of 4.5 months.

At baseline, the children wore a continuous glucose monitor (CGM) for 7–10 days, and review of CGM data revealed that the children who progressed to diabetes spent, on average, 21% of their time with glucose levels exceeding 140 mg/dL (7.8 mmol/L), compared with just 3% of the time for those who did not progress.

Spending more than 10% of the time with glucose levels above 140 mg/dL was 88% sensitive and 91% specific for distinguishing between progressors and nonprogressors, Andrea Steck (University of Colorado, Aurora, USA) and study co-authors report in Diabetes Care.

Children who met this threshold had an 80% chance of progressing within the next year, whereas those who did not meet it had just a 5% chance.

Other CGM metrics, such as the mean amplitude of glycaemic excursions and mean of daily differences, were also significantly associated with the likelihood for progression, but the researchers observe that time above 140 mg/dL is “graphically available on a CGM download and can be easily explained to participants and their families.”

They therefore propose this “as a new criterion for dysglycemia (stage 2 type 1 diabetes) with a high risk of progression to clinical diabetes within the next year in autoantibody-positive children.”

Steck and team add: “Current CGM devices, which do not need any calibration, are well accepted by children and their parents for monitoring diabetes risk and progression. They offer an accurate and nearly instantaneous measure of sensor glucose pattern for a participant over a few days in the real home environment.”

A cutoff of more than 15% of the time above 140 mg/dL was less sensitive for progression, at 69%, but was highly sensitive, at 99%, so the team suggests this as a measure of “imminent progression to clinical diabetes (i.e., within the next 6 months).”

Glycated haemoglobin was highly specific for progression to clinical diabetes, but had poor sensitivity, and oral glucose tolerance testing, while accurate, is “time consuming and unlikely to become part of routine diabetes monitoring,” say the researchers.

“In our experience, CGM has been well accepted by families,” they conclude.

“We propose that CGM could be done every 3–12 months, depending on the stage of type 1 diabetes and the age of the participant, although the optimal frequency of monitoring still needs to be further evaluated by examination of serial measurements.”

By Eleanor McDermid

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Diabetes Care 2021; doi:10.2337/dc21-0602