Estimating Plasma Glucose with FreeStyle Libre Pro CGM during OGTT in Youth

Objective: To evaluate the accuracy and practicality of the FreeStyle Libre Pro continuous glucose monitor (CGM) during oral glucose tolerance testing (OGTT) in a nondiabetic pediatric sample. Background: The FreeStyle Libre Pro CGM has been found, in adults, to have acceptable accuracy compared to lab-measured glucose without requiring individual patient calibrations. No studies have assessed lab-measured glucose accuracy for this CGM in children. Hypothesis: FreeStyle Libre Pro CGM glucose will not differ significantly from lab-measured plasma glucose during OGTT in youth. Methods: Healthy weight and overweight volunteers (n =8; 63% male), aged 7-11y wore FreeStyle Libre Pro Flash CGM for 6 days, with a 2-hour OGTT (1.75mg/kg, max 75g) on day 6. Laboratory (Cobas E6000, Roche) plasma glucose was measured at 30min intervals for 120min, and compared with the 15min average simultaneously obtained CGM glucose value. Glucose at each timepoint and Area Under the Curve (AUC) for CGM and lab-measured glucose were compared using paired t-tests. A correlation coefficient was calculated for each timepoint. Potential systematic errors were examined using Bland-Altman analyses. Results: AUC for CGM and lab glucose were well correlated (r= 0.91, p=0.006) and did not differ in mean value (p=0.84). CGM and lab glucose readings were not significantly different at any timepoint (all p’su003e0.18). There were no significant systematic or magnitude errors as assessed by Bland-Altman analyses at any timepoint. No adverse events occurred with CGM use and all participants considered the device easy to wear. Conclusions: The Freestyle Libre Pro CGM device was well tolerated and, even without individual calibration, provided quantitatively similar glucose readings during OGTT for healthy weight and overweight children when compared to lab-measured glucose. If confirmed in larger studies, this CGM may provide adjunctive data during evaluations of glucose excursions that may be useful for pediatric clinical care and research. Disclosure N. Ghane: None. M. Broadney: None. S.M. Collins: None. E.K. Davis: None. S. Brady: None. J.A. Yanovski: Research Support; Self; Rhythm Pharmaceuticals Inc., Zafgen.