Dexcom G7 vs FreeStyle Libre 3: Which CGM Is More Accurate?

What Was Studied — And Why It Matters

For people living with diabetes, a continuous glucose monitor (CGM) is more than a gadget — it's a safety tool. Accurate real-time readings help you make critical decisions about insulin, food, and activity. But how accurate are today's most popular CGM sensors, really?

Researchers from multiple clinical centers conducted the first direct, head-to-head accuracy comparison between the Dexcom G7 and the FreeStyle Libre 3 — the flagship devices from the two largest CGM manufacturers in the world. The results were published in the Journal of Diabetes Science and Technology in 2024.

How the Study Worked

55 adults with either Type 1 or Type 2 diabetes wore both sensors at the same time. Sensor readings were compared against highly accurate lab blood glucose measurements (called YSI reference values) as well as fingerstick blood glucose readings. Accuracy was measured using a standard called Mean Absolute Relative Difference (MARD) — essentially, how far off a sensor's readings are from the true value, on average. A lower MARD means better accuracy.

What the Researchers Found

The FreeStyle Libre 3 outperformed the Dexcom G7 on every accuracy measure tested:

• Overall MARD: FreeStyle Libre 3 scored 8.9% vs. Dexcom G7's 13.6% — a significant difference
• Readings within acceptable range: 91.4% of FreeStyle Libre 3 readings fell within the accepted accuracy window, compared to 78.6% for Dexcom G7
• Accuracy over time: Both sensors performed similarly in the first 12 hours of wear, but the FreeStyle Libre 3 maintained much better accuracy in the following 12 hours and beyond (10.0% vs. 15.1% MARD)
• Across all blood sugar levels: The FreeStyle Libre 3 was more accurate whether glucose was low, in-range, or high

What This Means for Real Patients

In plain terms: the FreeStyle Libre 3 gave readings closer to the true blood sugar value more consistently throughout the sensor's wear period. For patients making insulin dosing decisions or watching for hypoglycemia (low blood sugar), that difference in accuracy could genuinely matter.

It's worth noting that both sensors are widely used and FDA-cleared — this study doesn't mean the Dexcom G7 is unsafe, but it does suggest the FreeStyle Libre 3 may offer a measurable accuracy advantage in real-world wear conditions.

If you currently use either of these CGM systems and need replacement sensors, transmitters, or compatible supplies, MDS Diabetes carries a full range of CGM accessories to keep your monitoring routine on track without interruption.

Bottom Line

In the first-ever direct comparison of these two leading CGM systems, the FreeStyle Libre 3 demonstrated significantly better accuracy than the Dexcom G7 — especially after the first 12 hours of sensor wear. If you're choosing between CGM systems or discussing options with your care team, this research is worth bringing to your next appointment.