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Comparison of the Freestyle Libre Pro Flash Continuous Glucose Monitoring (CGM) System and Point-of-Care Capillary Glucose Testing (POC) in Hospitalized Patients with Type 2 Diabetes (T2D) Treated with Basal-Bolus Insulin Regimen

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posted on 11.06.2020, 16:49 by Rodolfo J. Galindo, Alexandra L. Migdal, Georgia M. Davis, Maria A. Urrutia, Bonnie Albury, Cesar Zambrano, Priyathama Vellanki, Francisco J. Pasquel, Maya Fayfman, Limin Peng, Guillermo E. Umpierrez
Background: We compared the performance of the FreeStyle Libre Pro continuous glucose monitoring (CGM) and point-of-care glucose testing among insulin-treated hospitalized patients with type 2 diabetes (T2D).

Methods: Prospective study in general medicine and surgery adult patients with T2D. Patient were monitored with POC before meals and bedtime, and with CGM during the hospital stay. Major endpoints included differences between POC and CGM in mean daily blood glucose, hypoglycemia < 70 and < 54 mg/dl, and nocturnal hypoglycemia. We also calculated the mean absolute relative difference (MARD), and ±15%/15mg/dl, ±20%/20mg/dl, ± 30%/30mg/dl, and Error Grid analysis between matched glucose pairs.

Results: Mean daily glucose was significantly higher by POC testing (188.9±37.3 vs. 176.1±46.9 mg/dl), and proportions of patients with glucoses < 70 mg/dl (14% vs 56%) and < 54 mg/dl (4.1% vs 36%) detected by POC BG were significantly lower compared to CGM, all p<0.001. Nocturnal and prolonged CGM hypoglycemia < 54 mg/dl was 26% and 12%, respectively. The overall MARD was 14.8%, ranging between 11.4 to 16.7% for glucoses between 70 and 250 mg/dl, and lower for 51- 69 mg/dL (MARD= 28.0%). The percentage of glucoses within the ±15%/15mg/dl, ±20%/20mg/dl, and ±30%/30mg/dl were 62%, 76%, and 91%, respectively. Error Grid analysis showed 98.0% of glucose pairs within Zones A and B.

Conclusions: Compared to POC testing, FreeStyle Libre CGM showed lower mean daily glucose and higher detection of hypoglycemic events, particularly nocturnal and prolonged hypoglycemia in hospitalized patients with T2D. CGM’s accuracy was lower in hypoglycemic range.


This work was an investigator-initiated grant, with unrestricted research support provided by Sanofi to Emory University. The funding source had no input on the design of the study, interpretation of the results or manuscript preparation.