Accuracy concerns offset flash glucose monitoring convenience in children with congenital hyperinsulinism
medwireNews: A trial of flash glucose monitoring shows that the technology is easy and convenient to use but may not be sufficiently accurate to be relied upon in children with congenital hyperinsulinism.
Researchers tested the FreeStyle Libre (FSL; Abbot Diabetes Care, Alameda, California, USA) system, which extrapolates blood glucose levels from readings in the interstitial fluid. When a sensor is passed over the monitoring device, it gives a current value plus glucose trends over the preceding 8 hours.
In this study of 11 children with congenital hyperinsulinism, aged between 0.5 and 5 years, the average mean absolute relative difference (MARD) between finger-prick capillary blood glucose and FSL readings across 467 matched readings taken over an average of 11.5 days was 17.9%.
Senthil Senniappan (Alder Hey Children’s Hospital, Liverpool, UK) and co-researchers note that this is larger than the MARD of 11–14% reported in studies of children with type 1 diabetes, which they say is in line with the hypothesis that “hyperinsulinemia may contribute to modest discrepancies between plasma and sensor glucose levels”.
Overall, the FSL overestimated finger-prick glucose levels, meaning it was a particular issue when children were hypoglycaemic. There were 42 episodes of symptomatic hypoglycaemia during the study period, in which blood glucose levels fell below 3.5 mmol/L, but the FSL readings identified only 52% of these episodes.
During hypoglycaemia, the FSL overestimated blood glucose on 66% of occasions, with differences ranging from 3% to 55%.
“This has its adverse effects from [a] practical point of view, as patients may have not been treated when they are truly hypoglycaemic”, write the researchers in the International Journal of Pediatric Endocrinology.
“This has obviously generated anxiety and less confidence amongst the parents to rely on FSL method to detect and manage hypoglycaemia.”
Indeed, only 37% of parents felt that the FSL was reliable, and just 18% said it was accurate. Nonetheless, 56% said they would like to continue using it, with most finding it very convenient for measuring glucose while the child slept and reporting that the glucose trend indicators helped them to predict and prevent hypoglycaemia.
“Further larger trials are needed in [congenital hyperinsulinism] patients before FSL is recommended as a routine alternative method for measuring glucose values”, concludes the team.
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