CGM Accuracy: Why It's No Longer the Whole Story

What This Study Found

A 2024 viewpoint published in The Lancet Diabetes & Endocrinology argues that nearly all modern continuous glucose monitors (CGMs) now meet acceptable accuracy standards. Because of this, accuracy scores alone are no longer a reliable way to tell devices apart. The authors say the conversation needs to shift toward bigger issues — like whether CGMs are being used consistently, whether they actually improve health outcomes, and whether everyone who needs one can get one.

Why Accuracy Used to Be the Main Selling Point

For years, CGM makers competed heavily on accuracy. A CGM's accuracy is often measured by something called Mean Absolute Relative Difference (MARD) — basically, how close the sensor's reading is to a lab blood glucose result. A lower MARD means a more accurate device.

In the early days of CGM technology, accuracy varied widely between devices. Patients and doctors had good reason to pay close attention to these numbers. But the researchers point out that today, almost every major CGM on the market clears the accepted accuracy threshold. Competing on MARD scores no longer tells the full story.

So What Should Matter Now?

The authors highlight three areas they believe deserve more attention going forward:

• Standardisation: CGM devices should report data in consistent, comparable ways so that doctors and patients can make meaningful comparisons and track progress reliably over time.
• Clinical outcomes: The real test of a CGM isn't just how accurate it is in a lab — it's whether using it leads to fewer low blood sugars, better HbA1c results, fewer hospital visits, and a better quality of life.
• Sustainability and access: CGMs only work if people can actually get them and keep using them. The authors raise concerns about inequalities in access, noting that many people who could benefit from CGM technology still cannot afford it or obtain it through their healthcare system.

What This Means for You

If you have type 1 diabetes or insulin-treated type 2 diabetes, this research is a reassuring sign — the CGM devices available today are more reliable than ever. But it's also a reminder to think beyond the spec sheet. When choosing or discussing a CGM with your care team, ask questions like: Will I be able to use this consistently? Does my insurance or healthcare plan cover it long-term? And does the data it gives me actually help me make better decisions?

At MDS Diabetes, we stock a range of CGM sensors and supplies designed to support consistent, long-term use. Whether you're just starting with CGM or looking to maintain your current routine, having a reliable supply source matters just as much as the device itself. Explore our CGM range at mdsdiabetes.com.

Citation: Oliver, Reddy, Leelarathna (2024). Continuous glucose sensor accuracy: beyond the headline metric. The Lancet Diabetes & Endocrinology. PMID: 39419044. DOI: 10.1016/S2213-8587(24)00245-6