The GNL Podcast

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

Dr. Stefan Pleus of the Institut für Diabetes-Technologie, Universität Ulm, and Chair of the IFCC Working Group on CGM, joins John Pemberton to explain what rigorous CGM performance testing actually requires — and what it will take to get there.

Listen and Watch

Need the foundations before diving in? Episode 19 with Dr. Guido Freckmann covers why current frameworks fall short:

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

And for the broader context, the CGM regulation FAQ is a useful starting point.

In This Episode

Dr. Stefan Pleus explains why the current FDA iCGM framework (2018) is no longer sufficient, what a robust international standard would look like, and why ISO standardisation by 2030 is essential if CGM is to:

Serve as a reliable basis for insulin dosing decisions.
Act as a trusted comparator in clinical trials.
Support screening and early diagnosis of type 1 diabetes.
Provide people with diabetes consistency across devices and manufacturers.

Key Insights from Dr. Stefan Pleus

“If you design your study material and methods to avoid rapid glucose changes, you will get good results — but that’s not real life. Many systems perform worse at high rates of change, and unless you test that, you don’t know the risk.”

“We introduced comparative data characteristics — requiring minimum data in low, high, and rapid change zones — so that stress test conditions are covered, not just the easy ones.”

“Every method has bias. Unless you retrospectively correct comparator results against higher-order reference materials and methods, you cannot align CGM readings across manufacturers.”

“With a more robust study design, today’s systems will look less accurate — not because they’ve changed, but because we’re finally stress-testing them properly.”

“An international standard typically takes 3–5 years. Without alignment between FDA and Europe, we risk duplication, cost, and stalled innovation. The biggest barrier is regulatory will, not the science.”

Why This Matters

Without standardisation, clinical trials, diagnostics, and everyday insulin dosing risk being inconsistent across devices. The opportunity — by 2030 — is to create a global, reproducible framework that ensures fairness for users, clarity for clinicians, and valid results for researchers.

Different CGM systems can report the same glucose level yet produce very different time-in-range values and different implied HbA1c readings. That inconsistency undermines trust, therapy adjustments, and clinical trial endpoints.

Related Resources

Related episodes:

IFCC Working Group on CGM publications:

Diabetes Care commentaries (2025) on CGM performance and standardisation:

Further reading:

PDF resource:

DSN-CGM-Comparsion-Charts-1.9.25

This content is for educational exploration only. It describes average responses and general principles. It is not medical advice and cannot replace individual clinical guidance from your diabetes care team.