MARD — Mean Absolute Relative Difference — is the standard accuracy metric for CGM devices. Lower is more accurate. This ranking uses published pivotal trial data for all six CGMs available in the US in 2026.
Medical Disclaimer: This content is for informational purposes only. Always consult your healthcare provider before making health decisions.
FreeStyle Libre 3 (7.8% MARD) is the most accurate prescription CGM and has the best-documented single MARD figure of any device on this list. Among OTC devices, published FDA ranges overlap and are not directly comparable: Dexcom Stelo (7.3–9.1% MARD) and Abbott Lingo (8.1–10.7% MARD) — Lingo is the cheapest OTC option at ~$89/month, built on the FreeStyle Libre sensor platform.
Devices reporting a single MARD figure and devices reporting a range are not directly comparable — a range reflects performance variability across the study, not a single average. Order below is for reference only.
| Rank | Device | MARD | Rx required | Monthly cost | Source |
|---|---|---|---|---|---|
| 1 | FreeStyle Libre 3 | 7.8% | Yes | ~$130 | Abbott pivotal trial |
| 2 | Dexcom G7 | 8.2% | Yes | ~$350 | Dexcom pivotal trial |
| 3 | Medtronic Guardian 4 | 8.8% | Yes | Varies | Medtronic pivotal trial |
| 4 | Eversense E3 | 9.1% | Yes + procedure | Varies | PROMISE trial |
| — | Dexcom Stelo | 7.3–9.1% (range) | No (OTC) | ~$99 | Dexcom pivotal trial |
| — | Abbott Lingo | 8.1–10.7% (range) | No (OTC) | ~$89 | Abbott pivotal trial |
MARD (Mean Absolute Relative Difference) measures how far a CGM reading deviates from a simultaneous reference blood glucose measurement, expressed as a percentage. A MARD of 7.9% means the CGM reads within 7.9% of the true glucose value on average across all measurements in the clinical trial.
Lower MARD = more accurate. A device with 7.9% MARD will, on average, read closer to the true glucose value than a device with 8.7% MARD. The practical significance of a 0.8% difference is small for most users but can matter in critical situations — particularly in the hypoglycemic range where accuracy is most clinically important.
Different trial populations and reporting methods: Abbott Lingo's FDA submission reports an 8.1–10.7% MARD range, based on the same pivotal sensor data as the Libre 2 platform, studied in people with diabetes; FreeStyle Libre 3's 7.8% single-figure MARD comes from its own pivotal trial, also in people with diabetes. A range and a single average are not directly comparable, and neither is directly comparable to Dexcom's figures, which come from separate trials with their own populations and methods.
Range performance varies: Some devices perform better in the hypoglycemic range (below 70 mg/dL) than overall MARD suggests. Dexcom G7 is specifically noted for strong accuracy in the low glucose range, which is clinically important for insulin-dependent users.
Real-world vs clinical: MARD from pivotal trials may differ from real-world performance due to sensor placement, activity, temperature, and individual variation.
MARD, sensor life, cost, and clinical notes — all in one place.
Abbott Lingo (8.1–10.7% MARD) — available without a prescription at ~$89/month, the lowest price of any OTC device. Its published FDA range is higher (less accurate) than Dexcom Stelo's 7.3–9.1% range, though the two ranges overlap and are not directly comparable. Lingo's main advantage is price and the FreeStyle Libre sensor platform, not accuracy.
FreeStyle Libre 3 (7.8% MARD) — available with a prescription at ~$130/month retail. Best published accuracy of any prescription CGM. Reads every minute, lasts 14 days.
Dexcom G7 (8.2% MARD) — slightly less accurate than Libre 3 overall but required for most AID (automated insulin delivery) systems. Notably strong accuracy in the hypoglycemic range.
Every device side by side — 30, 90, or 365 days.
Accuracy, cost, sensor life, and who each device is best for — in one comparison.
Compare all CGM devices →