Episode 19 – iCGM vs eCGM vs Standardisation by the IFCC: CGM Regulation with Dr. Guido Freckmann

🎧 Listen now:

Overview

Continuous glucose monitoring (CGM) has transformed diabetes care — but how do we know which systems are accurate, safe, and truly comparable?

In this episode, John Pemberton is joined by Dr. Guido Freckmann (Institute of Diabetes Technology, Ulm; former chair of the IFCC CGM Working Group). Together they unpack:

  • Why CE marking in Europe is not a quality standard
  • How the FDA’s iCGM framework (2018) was groundbreaking, but has limitations in study design
  • Why the proposed eCGM model for Europe risks monopolising the market without fixing accuracy problems
  • The IFCC’s roadmap towards a full ISO standard for CGM – robust, reproducible, and aligned with clinical reality

Need the 101 before diving in?

CGM Regulation FAQ: Got T1D? It’s THE most important thing you will read this year!

Once you’ve listened to this episode, the next step is looking at how we get to a true international standard.

Episode 20 — Standardization of Testing CGM Performance: The Nuts and Bolts

Key Themes & Watch-Outs

🔹 CE Mark ≠ Quality Standard

  • CE marking is a regulatory pathway, not a guarantee of performance.
  • Manufacturers can submit selective data, and the results are not public.

🔹 ICGM (2018): A Step Forward, But Outdated

  • FDA ICGM rules set minimum standards, but study design criteria were vague.
  • Devices can appear accurate by avoiding stressful glucose swings.

🔹 Why Standardisation Matters

  • Standardisation would define not just performance metrics but also how studies are run.
  • It would align CGM systems to the same comparator (capillary or venous) and reduce therapy discrepancies.

🔹 Capillary vs Venous Debate

  • Capillary glucose reflects what people actually test and what their bodies are exposed to.
  • Venous alignment risks giving a “false reassurance” of being in range.
  • An agreement is needed: whichever is chosen must be standardised, with bias correction.

🔹 Clinical Impact

  • Different CGMs can give the same time-in-range but very different HbA1c and complication risk.
  • That undermines trust, confuses therapy adjustments, and makes clinical trial endpoints unreliable.

🔹 Looking Ahead

  • CGM standardisation is in motion, but likely won’t be implemented before 2030.
  • Until then, clinicians and people with diabetes need to scrutinise study design and remain critical of performance claims.

Quotes from the Episode

“CE marking is not a quality standard. You have to dig into study design — and that’s not practical for the average person with diabetes or most clinicians.” – John Pemberton

“CGM systems often perform worse at high rates of change than at stable glucose levels. That’s why stress-testing is vital.” – Dr. Guido Freckmann

“Different CGM systems can give the same time-in-range but very different HbA1c and complication risks. That’s unacceptable.” – John Pemberton

“Manufacturers can design studies to get good results by avoiding rapid glucose swings. Without rules, accuracy is only on paper.” – Dr. Guido Freckmann

Now it’s time for Episode 20 with Stefan Pleus, Chair of the IFCC Working Group for CGM, on what a standardised CGM Evalauton study design looks like.

Episode 20 — Standardization of CGM Performance Testing: The Nuts and Bolts

Key publications (all open access):

1️⃣ Freckmann et al. (2025) — Comparative Analysis of Three CGMs Against Capillary Glucose
👉 Found substantial differences between CGM systems reporting the same true glucose.

🔗 Read here

2️⃣ Beck et al. (2025 Commentary) — Researcher Concerns
👉 Raised issues about study design, comparator validity, and the risk of misleading trial conclusions.

🔗 Read here

3️⃣ Pemberton et al. (2025 Commentary) — Clinical Concerns
👉 Highlighted the implications for clinical decision-making, T1D screening, and patient confidence if sensors remain inconsistent.

🔗 Read here

4️⃣ Waldenmaier et al. (2025 Response) — Author Reaffirmation

👉 Confirmed the concerns: without traceable comparators and standardised protocols, findings can mislead research and practice.

🔗 Read here

Why This Matters

If CGM is to become the backbone of diabetes care — from insulin dosing to clinical trial endpoints and early diagnosis — standardisation is essential. Without it, people with diabetes, clinicians, and researchers will continue to face inconsistent data, misplaced trust, and misleading outcomes.

This conversation makes clear: the future of CGM depends on pushing beyond CE marks and ICGM criteria, towards a global ISO standard.