Implantable Continuous Glucose Monitor Safe, Effective in Diabetes

An implantable continuous glucose monitor appears to be a safe and effective alternative to a transcutaneous monitor in diabetes.

A new implantable continuous glucose monitoring (CGM) system appears to be a safe and accurate alternative to a transcutaneous system for patients with diabetes, according to data published in Diabetes Care.

“Implantable CGM systems may provide additional ease of use over transcutaneous CGM since frequent sensor insertions thorugh the skin are not needed and the transmitter can be removed easily without the need for sensor replacement, for example during personal care,” researchers wrote. “Furthermore, weekly sensor replacement with warm-up time and the risk of damage to the inserted sensor is no longer applicable.”

Even so, they noted, an implantable device would require a minor surgical procedure that may prove problematic for some patients. Moreover, long-term data on an implantable sensor are lacking.

To add to the body of evidence, the researchers evaluated the Eversense (Senseonics Inc) implantable CGM sensor in 71 adults with type 1 and type 2 diabetes. In the multinational, multicenter, 180-day PRECISE trial (A Prospective, Multi-Center Evaluation of the Accuracy of a Novel Continuous Implanted Glucose Sensor; identifier: NCT02154126), the CGM system was used at home and in the clinic, and accuracy was assessed during 8 in-clinic visits. The primary efficacy outcome was mean absolute relative difference (MARD) for venous reference glucose values greater than 4.2 mmol/L.  

For the implantable CGM system, the MARD value against the reference was 11.1% (95% confidence interval [CI], 10.5-11.7). In the hypoglycemic range, defined as 4.2 mmol/L or lower, was less than its overall performance (2.2 mmol/L to 22.0 mmol/L): 21.7% vs 11.6% MARD (P <.001).

Real-time reanalyses using a new data algorithm suggested improved performance over the currently used algorithm, with MARD values against the reference of 10.5% for overall performance (P <.001) and 18.6% for the hypoglycemic range (P <.001).

According to Clarke Error Grid Analysis, the estimated clinical performance of the implantable CGM system indicated that 99.2% of samples were in the clinically acceptable error zones A (84.3%) and B (14.9%). In terms of the in-clinic alarm performance for the thresholds of hypoglycemia, defined as less than 3.9 mmol/L, and hyperglycemia, defined as greater than 10 mmol/L, confirmed detection rates were 81% and 88%, respectively, with true event rates of 67% and 90%, respectively.

From baseline to the study’s conclusion, HbA1c improved from 7.54% to 7.19%. For those with a baseline HbA1c of less than 7.5%, HbA1c did not change significantly (–0.04%; P =.669) at the final study visit, according to a post-hoc analysis. Those with a baseline HbA1c of 7.5% or greater, however, experienced a decrease of 0.55% (P <.001).

Kaplan-Meier analysis estimated that 100%, 82%, and 40% of sensors were functional during in-clinic sessions at days 45, 90, and 180, respectively, with a median sensor life of 149 days.

In terms of safety, the researchers found no severe procedure- or device-related serious adverse events. In 11 patients, 14 device- or procedure-related nonsevere adverse events occurred, with 147 devices implanted, use, and removed. There were 5 cases of skin reaction, but therapy resumed in all cases after a temporary stop of 1 to 3 weeks. Two cases of incision site infection occurred, with 1 patient receiving antibiotic treatment and the other resolving without further medical intervention.

“The results from this study indicate that the use of a long-term implantable continuous glucose sensor is both effective and safe and provides specific usability benefits,” the researchers concluded. “The results support implantable CGM as a worthy alternative to current transcutaneous CGM.”

Disclosures: This study was funded by Senseonics Inc, manufacturer of the implantable CGM. One researcher is also an employee of Senseonics Inc. Several other researchers have reported relationships with one or more of the following: Senseonics, AstraZeneca, Eli Lilly and Company, Bristol-Myers Squibb, Sanofi, Boehringer Ingelheim, Novartis, Novo Nordis, Berlin-Chemie, Dexcom, Johnson & Johnson, and Roche Diagnostics.

Related Articles


  1. Kropff J, Choudhary P, Neupane S, et al. Accuracy and longevity of an implantable continuous glucose sensor in the PRECISE study: a 180-day, prospective, multicenter, pivotal trial. Diabetes Care. 2016 Nov 4. doi:10.2337/dc16-1525.