Continuous Flash Glucose Monitoring in children with Congenital Hyperinsulinism; first report on accuracy and patient experience

Abstract

BackgroundThe factory calibrated FreeStyle Libre (FSL) flash glucose monitoring system has been recently introduced for use in patients with diabetes mellitus. There are no reports available regarding its use in patients with congenital hyperinsulinism (CHI). We have assessed the accuracy of FSL compared to the finger prick capillary blood glucose (CBG) over 2 weeks period in patients with CHI and evaluated the parents’ experience of using FSL.MethodsFour hundred sixty-seven episodes of CBG along with corresponding swipe FSL readings were available from 11 children with CHI (0.5–5 years). A detailed questionnaire was completed by the parents.ResultsThe mean variation between the two methods was 0.29 mmol/l (SD ±1.07), higher readings by FSL compared to CBG. The FSL sensors stayed in-situ for an average period of 11.5 days. There was a positive correlation between the two methods (r = 0.7). The FSL tended to overestimate compared to CBG (bias = 0.29 mmol/l; 95% CI: 0.19 to 0.38). Only 70% of values were within the reference standard (±0.83 mmol/l) at glucose concentrations less than 5.6 mmol/l. The overall Mean Absolute Relative Difference (MARD) was 17.9%. Forty two episodes of hypoglycaemia (CBG < 3.5 mmol/l) were noted but FSL identified only 52% of these episodes. The Bland Altman analysis showed the 95% limits of agreement between the two methods ranging from − 1.8 (95% CI: -1.97 to − 1.64) to 2.37 (95% CI: 2.21 to 2.54). Majority of the parents found the glucose trend on FSL to be useful to detect and prevent hypoglycaemic episodes. All parents felt that FSL is a very easy and convenient method to measure the glucose especially during sleep. A significant proportion of parents felt that FSL readings were not accurate and 56% of parents expressed interest to continue using FSL after the trial period.ConclusionNoticeable variability between the two methods of measuring the glucose was noted. Despite the ease of using the FSL system, concerns related to accuracy, especially at low glucose values do remain although parents find the glucose trend to be very useful. Further larger trials are needed in CHI patients before FSL is recommended as a routine alternative method for measuring glucose levels.

Differences Between Flash Glucose Monitor and Fingerprick Measurements

“…Several studies have reported an overall performance of the FL comparable to that of other state-of-the-art CGM systems [7,20,21,22,23,24,25,26,27,28,29]. Our main results are in line with previous observations as we find an overall MARD of 12.3% and half of the participants having a MARD at or below 10%.…”

“…Several of the previous FL performance studies also report individual MARDs, where some are as large as we observed in our study [7,22,27]. The studies by Ólafsdóttir et al [21] and Alsaffar et al [24] report a bias in the measurements, but on an overall level only. To the best of our knowledge, the present study is the first to report on individual bias and lag issues as reasons for the high variation in individual MARDs in FL.…”

Hyperinsulinemic hypoglycemia in children and adolescents: Recent advances in understanding of pathophysiology and management

“…CGM measures interstitial glucose concentrations indicating the direction, magnitude, frequency, duration and causes of fluctuations in these. There is now a study on its accuracy in children with HH [ 93 ], as this can significantly improve the quality of life of these patients.…”

“…There is now more research of use of CGM in children with HH which might help to detect early hypoglycemia leading to prompt management [ 93 ]. There have been reports of pitfalls of 18F-DOPA PET-CT in accurately detecting focal lesions in CHH [ 106 , 173 ].…”

Open-Source Technology for Real-Time Continuous Glucose Monitoring in the Neonatal Intensive Care Unit: Case Study in a Neonate With Transient Congenital Hyperinsulinism

“…Caregivers found the indication of glucose trends to be helpful, felt more confident in everyday management of the condition, and felt less worried about the occurrence of asymptomatic hypoglycemia [ 12 , 14 ]. However, older rtCGM/isCGM systems were reported to have limited accuracy, especially for hypoglycemic levels, and therefore not recommended to completely replace capillary blood glucose (CBG) testing, but rather seen as an adjunctive, beneficial therapy [ 13 , 15 ].…”