This content is for informational purposes only. Always consult your healthcare provider before making health decisions. CGM accuracy data comes from manufacturer-sponsored clinical studies; real-world accuracy may vary.
The sources below report different summaries. Original Libre 3 and G7 have their own study results; Lingo’s selected glucose-bin figures and Stelo’s historical adult wear-period range are not pooled overall MARD. Read model, population and reference method with each figure.
What MARD means and why it matters
MARD stands for Mean Absolute Relative Difference. It is the standard accuracy metric for CGM devices, calculated by comparing CGM readings to a reference blood glucose measurement (typically a laboratory glucose analyzer) across many paired readings during a clinical trial.
The formula is simple: for each paired reading, the absolute percentage difference between the CGM reading and the reference is calculated. MARD is the average of those percentage differences across the full study dataset.
A lower MARD means a smaller average difference in that study. A MARD of 7.8% means the device's readings differed from the reference by 7.8% on average in that study. MARD figures from different studies, protocols and reference methods cannot be compared directly, so a 7.8% figure and a 9.0% figure from separate studies do not show that one device is more accurate.
MARD summarizes average absolute relative differences in a study. It is one measure of performance; it does not replace the complete study results, the device indication or its current instructions.
Accuracy depends on the device, glucose range and measurement conditions. A study-wide MARD does not guarantee the accuracy of an individual reading. Follow the current instructions for your specific device and discuss clinical decisions with your healthcare professional.
Compare accuracy and costs across all major CGMs.
Published MARD by device: 2026 data
This comparison quotes study figures for specifically named sensor models. Do not transfer a figure from the original Libre 3 to a Plus variant or to another sensor; consult current manufacturer documentation for the model you will use.
FreeStyle Libre 3: 7.8% MARD
This comparison quotes study figures for specifically named sensor models. Do not transfer a figure from the original Libre 3 to a Plus variant or to another sensor; consult current manufacturer documentation for the model you will use.
Abbott Lingo: 8.1–10.7% MARD (by glucose range)
Published MARD figures come from separate manufacturer studies and do not establish which device is more accurate. Choose a device based on its intended use and the features you need with advice from your healthcare professional, and check manufacturers for current prices.
Dexcom G7: 8.2% MARD (10 Day) / 8.0% MARD (15 Day)
Published MARD figures come from separate manufacturer studies and do not establish which device is more accurate. Choose a device based on its intended use and the features you need with advice from your healthcare professional, and check manufacturers for current prices.
Dexcom Stelo: 7.3–9.1% MARD (by wear period)
Published MARD figures come from separate manufacturer studies and do not establish which device is more accurate. Choose a device based on the features you need with advice from your healthcare professional, and check manufacturers for current prices.
Full accuracy comparison table
| Device | MARD | Sensor life | Monthly cost | Rx required |
|---|---|---|---|---|
| Dexcom G7 15 Day | 8.0% | ~15.5 days | Check price | Yes |
| Abbott Lingo | 8.1–10.7% (by glucose range) | 14 days | Check price | No |
| FreeStyle Libre 3 | 7.8% | 14 days | Check price | Yes |
| FreeStyle Libre 3 Plus | 8.2% adults / ages 6–17 (manufacturer, YSI); 9.7% ages 2–5 (BGM) | Up to 15 days | Check price | Yes |
| Dexcom G7 (10 Day) | 8.2% | 10 days | Check price | Yes |
| Dexcom Stelo | 7.3–9.1% (historical adults, by wear period) | 15 days | Check price | No |
Published study figures use different protocols and reference methods. Check manufacturers, pharmacies and your insurer for current prices and coverage.
Accuracy isn't the whole picture; it doesn't tell you what you'll pay, whether a device needs a prescription, or which plan fits how you'll use it. For OTC access, pricing, and plan details, see our Stelo cost and plans breakdown and Stelo vs Abbott Lingo comparison.
Compare current CGM costs using prices you enter yourself.
What affects real-world CGM accuracy
Sensor placement
Approved sites depend on device and age: US G7 uses the back of the upper arm, with upper buttocks also allowed at ages 2–6; G7 15 Day uses the back of the upper arm in adults. Follow the exact model instructions, not general placement advice.
Compression lows
A low reading may be real or an artifact, including pressure on a sensor. Do not dismiss an isolated low or assume a position change resolves it. Follow your device instructions and care plan for low readings, symptoms or a mismatch with a blood glucose measurement.
Calibration
Calibration requirements and any need to confirm readings with a blood glucose meter are device-specific. Follow your current device instructions, including what to do when a reading does not match your symptoms.
Altitude
Accuracy depends on the device, glucose range and measurement conditions. A study-wide MARD does not guarantee the accuracy of an individual reading. Follow the current instructions for your specific device and discuss clinical decisions with your healthcare professional.
Extreme temperatures
Accuracy depends on the device, glucose range and measurement conditions. A study-wide MARD does not guarantee the accuracy of an individual reading. Follow the current instructions for your specific device and discuss clinical decisions with your healthcare professional.
Rapid glucose changes
Interstitial glucose can lag behind blood glucose; the lag depends on the device and the situation. During periods of rapid change (right after meals or during intense exercise), the CGM reading may differ meaningfully from a simultaneous blood glucose measurement.
Accuracy during exercise versus rest
Accuracy depends on the device, glucose range and measurement conditions. A study-wide MARD does not guarantee the accuracy of an individual reading. Follow the current instructions for your specific device and discuss clinical decisions with your healthcare professional.
Accuracy depends on the device, glucose range and measurement conditions. A study-wide MARD does not guarantee the accuracy of an individual reading. Follow the current instructions for your specific device and discuss clinical decisions with your healthcare professional.
Accuracy depends on the device, glucose range and measurement conditions. A study-wide MARD does not guarantee the accuracy of an individual reading. Follow the current instructions for your specific device and discuss clinical decisions with your healthcare professional.
Interpreting the published figures
Abbott Lingo: OTC CGM
Published MARD figures come from separate manufacturer studies and do not establish which device is more accurate. Choose a device based on its intended use and the features you need with advice from your healthcare professional, and check manufacturers for current prices.
Read full Lingo review →Read each model’s study separately
This comparison quotes study figures for specifically named sensor models. Do not transfer a figure from the original Libre 3 to a Plus variant or to another sensor; consult current manufacturer documentation for the model you will use.
Read full Libre 3 review →Compare all CGM costs for any monitoring period.