PRECISE II: Accuracy of the new Eversense implantable CGM system

Christiansen MP, Klaff LJ, Brazg R et al (2018) A prospective multicenter evaluation of the accuracy of a novel implanted continuous glucose sensor: PRECISE II. Diabetes Technol Ther 20: 197–206

• PRECISE II was a 90-day, single-arm, prospective, blinded study to evaluate the safety and accuracy of the Eversense system (Senseonics Inc., Germantown, MD, USA), a novel implantable continuous glucose monitoring (CGM) system that comprises a subcutaneous sensor designed to operate for 90 days, a smart transmitter and an app that displays the resulting blood glucose data.
• In total, 90 adults with type 1 or type 2 diabetes wore the sensor and transmitter, with all CGM values and blood glucose alerts blinded. They continued their usual diabetes self-care in addition to calibrating the CGM system twice daily using fingerstick testing. The accuracy of the system was tested every 30 days by comparing CGM glucose values with those measured by a bedside glucose analyser.
• The primary endpoint, mean absolute relative difference (MARD) over the blood glucose range of 2.2–22.2 mmol/L, was 8.8% (95% confidence interval [CI], 8.1–9.3%), and 93.3% of CGM glucose readings were within ±1.1 mmol/L or 20% of the reference values. In Clarke Error Grid analysis, 99.3% of samples were in the clinically acceptable error zones A and B.
• Compressing the sensor, by having participants lie on it for 30 minutes, simulating sleep, had no significant effect on accuracy, and neither did exercise.
• There were 14 treatment-related adverse events in seven participants, mostly mild and involving bruising or discomfort. One serious adverse event occurred, involving surgery under general anaesthesia to remove the device, resulting from the sensor being placed to deeply at insertion.
• Adherence was high, with 82 participants completing the study and spending a median of 23.4 hours per day wearing the device. Five participants required a sensor replacement within 90 days, which ended glucose data collection.
• The authors conclude that the Eversense device was accurate and safe over 90 days. Future studies are planned to assess the clinical utility of the device in non-blinded conditions, and over longer periods involving multiple sensor changes.

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