Published in the Journal of Diabetes Science and Technology, the study evaluated the latest-generation Abbott FreeStyle Libre 3, Dexcom G7 and Medtronic Simplera CGMs against different comparator methods and during clinically relevant glycemic scenarios.
The study evaluated 24 adult participants with type 1 diabetes mellitus. They wore one sensor of each CGM system in parallel for up to 15 days. Participants exchanged sensors for G7 and Simplera on days five and eight, respectively. They underwent three seven-hour sessions with 15-minute comparator glucose-level measurements collected through the YSI 2300 (YSI, venous), Cobas Integra (INT, venous), and Contour Next (CNX, capillary) on days two, five and 15. Simultaneously, glucose-level excursions with transient hyperglycemia and hypoglycemia were induced.
Investigators measured accuracy using various metrics, including mean absolute relative difference (MARD). Lower MARD indicates higher accuracy.
Compared with YSI data, MARD came in at 11.6% for FreeStyle Libre, 12% for G7 and 11.6% for Simplera. Relative to the INT data, MARD registered at 9.5% for Libre, 9.9% for G7 and 13.9% for Simplera. Compared with CNX data, MARD totaled 9.7% for Libre, 10.1% for G7 and 16.6% for Simplera.
The study demonstrated better accuracy from FreeStyle Libre 3 and G7 in the normoglycemic and hyperglycemic range. Simplera performed better in the hypoglycemic range.
Investigators concluded: “Performance results of all CGM systems varied depending on the comparator method. However, across comparators [FreeStyle Libre 3] and [G7] tended to be more accurate compared with [Simplera]. All CGM systems showed a lower accuracy compared with previous studies, emphasizing the need for comprehensive study design guidelines.”
What the CGM data from Abbott, Dexcom and Medtronic told investigators
Investigators undertook this study to evaluate how different device characteristics influence glycemic control metrics for CGMs. They say it remains challenging to compare CGM performance and evaluate the reliability of provided therapy metrics because of a lack of comprehensive and detailed guidelines describing procedures for the standardized performance testing of CGMs.
To address this issue, they designed a study incorporating procedures to address the clinical performance of the leading CGM systems.
“We thus argue that our study procedures can effectively identify weaknesses in performance, which, if implemented in a future standard, can help ensure the continued safety and reliability of CGM systems as an increasing number of manufacturers enter the market,” the investigators say. “In addition, a direct comparison of CGM system performance allows users to understand the strengths and weaknesses of each system.”
