New CGM System Becomes First to Meet European Accuracy Standards

A continuous glucose monitoring system marketed in Europe has, for the first time, been formally shown to satisfy a proposed set of European clinical performance criteria for CGM devices, according to a pooled analysis published in Diabetes Therapy. The device, the CareSens Air system developed by i-SENS, Inc. of the Republic of Korea, achieved accuracy figures across hypoglycemic, euglycemic, and hyperglycemic glucose ranges that meet or exceed the thresholds laid out in the so-called eCGM framework, a set of minimum expectations drafted by diabetes technology experts to close a long-standing regulatory gap in Europe. The finding matters because it suggests that a CGM sensor sold under the European CE-marking regime can be trusted not merely as an adjunctive monitoring tool but as the basis for real insulin dosing decisions and for integration with automated insulin delivery systems.

To understand why this result is attracting attention, it helps to look at the regulatory asymmetry between the two sides of the Atlantic. In 2018, the United States Food and Drug Administration created the “integrated” CGM, or iCGM, designation, a performance-based regulatory pathway that imposes stringent accuracy and interoperability standards on manufacturers. Devices cleared under this pathway can reliably “integrate” with other digitally connected health technologies, including insulin pumps and smart pens, because regulators have verified their performance across the full measuring range. In Europe, by contrast, CGM systems have traditionally entered the market through CE marking, a process that assesses general safety and performance but has been criticized in the clinical literature as less stringent, less device-specific, and less transparent than the FDA approach. For patients and clinicians, this has meant that two sensors carrying the same CE mark could, in principle, perform very differently.

The eCGM proposal was formulated to address precisely this concern. Largely mirroring the FDA’s iCGM requirements, the eCGM criteria specify accuracy expectations across three glycemic strata, define limits for paired glucose comparisons against laboratory reference measurements, set confidence interval thresholds for proportional agreement, and impose demanding requirements on how the supporting clinical study must be designed. Among these design requirements are a minimum of 100 participants, a majority with type 1 diabetes, sensors drawn from at least three manufacturing lots, the use of laboratory-grade reference analyzers, and crucially a distribution of comparator glucose values in which at least 8 percent fall below 70 mg/dL and at least 5 percent exceed 300 mg/dL. That last requirement is far from trivial: recruiting enough data points at dangerously low and very high glucose levels, while keeping participants safe, is one of the hardest parts of CGM performance testing.

The new analysis, led by Nina Jendrike and Guido Freckmann of the Institut für Diabetes-Technologie Ulm GmbH together with Korean collaborators, assembled a pooled dataset from three clinical investigations to meet these stringent conditions. The first pivotal study, conducted in the Republic of Korea between February and August 2022 with 84 participants, supported national regulatory approval in 2023. A second pivotal study, run in Germany between May and October 2022 with 50 participants, contributed to the CE marking granted in early 2024. Because the two pivotal trials together did not quite reach the glycemic distribution demanded by the eCGM proposal, the team added a post-market clinical follow-up study between October and December 2025, enrolling 30 additional participants specifically to generate supervised hypoglycemic and hyperglycemic excursions, with venous blood sampled as frequently as every five minutes during those episodes.

The resulting pooled dataset comprised 164 participants, of whom 86 percent had type 1 diabetes, half were female, and two-thirds managed their diabetes with multiple daily injections. Across the three studies, 168 primary sensors were worn, and 163 of them yielded 17,655 paired CGM-comparator measurements suitable for the accuracy analysis. Of these pairs, 10.9 percent had reference plasma glucose values below 70 mg/dL and 5.7 percent exceeded 300 mg/dL, comfortably satisfying the eCGM distribution requirements. All CGM readings were retrospectively generated by the manufacturer using the currently marketed optional-calibration algorithm applied to the recorded raw sensor signals, while the statistical analysis itself was carried out independently by the investigators.

The headline numbers are striking. In the hypoglycemic range, where CGM accuracy matters most for safety, approximately 91.0 percent of sensor readings below 70 mg/dL fell within ±15 mg/dL of the paired laboratory value, placing the device at the upper end of the 85.7 to 93.2 percent range reported for FDA-cleared iCGM systems. In the euglycemic range of 70 to 180 mg/dL, 78.6 percent of readings agreed with the comparator within ±15 percent, rising to 84.4 percent in the hyperglycemic range above 180 mg/dL, where competing iCGM devices have reported 85.5 to 92.6 percent. Overall, 90.3 percent of all readings landed within ±20 percent of the reference value across the measuring range, and the pooled mean absolute relative difference, a widely cited accuracy metric known as MARD, came out at 9.5 percent. Consensus Error Grid analysis reinforced the clinical picture: 94.6 percent of readings fell into zone A, meaning no effect on clinical action, 5.4 percent into zone B with little or no effect on outcome, and essentially none into the zones representing meaningful clinical risk.

Beyond raw accuracy, the analysis probed how performance holds up over the sensor’s 15-day wear period, a question of real practical importance since CGM accuracy often drifts at the beginning and end of sensor life. Accuracy was slightly lower during the first three days of wear but then stabilized and remained consistent through day 15, a pattern the authors describe as in line with modern CGM technologies. Kaplan-Meier survival analysis, which included all 168 primary sensors, estimated a 90.2 percent probability that a sensor would survive to the end of its expected 15-day-and-30-minute lifetime, with a mean survival time of 14.4 days. Data availability averaged 99.7 percent, and of the 267 data gaps identified, over 91 percent lasted less than 15 minutes; only two gaps exceeded one hour, both traced to smartphone-related user issues rather than sensor malfunction. Safety findings were similarly reassuring: eight adverse device effects were recorded, all mild and non-serious, consisting of erythema, skin pressure marks, and minor bleeding at insertion sites, all recognized and expected consequences of CGM use.

The authors are careful to situate these results within their limits. The analysis was conducted under controlled clinical conditions, so real-world performance may vary with physiological and environmental factors, and the study population excluded children and pregnant women, meaning results cannot simply be generalized to those vulnerable groups. The pooled dataset, while heterogeneous in study design and population, was also funded by the device manufacturer, which provided the systems and retrospectively generated the CGM readings, although the investigators retained independent control over the statistical analysis and interpretation. The eCGM framework itself remains a proposal rather than a formally established European regulatory requirement, and the authors note that further consensus among clinicians, regulators, and manufacturers will be needed before it can be embedded in official guidance. In parallel, the IFCC Working Group on CGM has developed its own comprehensive guideline aimed at a formal ISO standard, signaling that the regulatory landscape for glucose sensors is consolidating rapidly.

Even with those caveats, the significance of the result is hard to overstate. This is the first time that explicit compliance with the eCGM accuracy criteria has been demonstrated for any CGM system, and notably it was achieved by a device that has not itself received FDA iCGM clearance, a status that would otherwise have implied such compliance. For the roughly millions of Europeans who rely on CGM to steer insulin therapy, the study offers something previously absent from the CE-marking landscape: a transparent, quantified, internationally benchmarked demonstration that a sensor can read glucose accurately enough to dose insulin on, detect hypoglycemia dependably, and feed data continuously to an automated insulin delivery algorithm. As CGM technology becomes the backbone of closed-loop diabetes care, independent verification of the numbers behind those algorithms is not a technicality. It is the foundation on which patient safety, and the next generation of automated diabetes therapy, will be built.

Subject of Research: Clinical performance of the CareSens Air CGM system against the proposed European eCGM accuracy criteria

Article Title: Performance of the i-SENS CareSens Air CGM System in Compliance with the European CGM (eCGM) Clinical Performance Criteria: A Pooled Analysis

Article References: Jendrike, N., Kim, K.-S., Lee, S.-H., Yoo, W. S., Park, C.-Y., Öter, S., Morent, L., Eichenlaub, M., & Freckmann, G. (2026). Performance of the i-SENS CareSens Air CGM System in Compliance with the European CGM (eCGM) Clinical Performance Criteria: A Pooled Analysis. Diabetes Therapy. https://doi.org/10.1007/s13300-026-01917-w

Image Credits: AI Generated

DOI: 10.1007/s13300-026-01917-w

Keywords: continuous glucose monitoring, eCGM, CareSens Air, diabetes technology, sensor accuracy, MARD, insulin dosing, automated insulin delivery, hypoglycemia, CE marking, clinical performance, i-SENS