Continuous Glucose Monitors (CGMs) represent the cutting edge of diabetes management technology, providing real-time glucose readings without the need for fingerstick testing. These devices use a small sensor inserted under the skin to measure glucose levels continuously throughout the day and night.
Our comprehensive analysis examines the top CGM systems available in 2025, evaluating accuracy (MARD), sensor longevity, insurance coverage, user experience, and real-world reliability based on thousands of verified user reviews.
Whether you have Type 1 diabetes, Type 2 diabetes requiring intensive insulin management, or experience hypoglycemia unawareness, this guide will help you choose the right CGM system for your needs.
What You'll Find in This Review
- 3 top CGM systems reviewed with detailed accuracy data and real-world performance
- MARD accuracy comparison from independent clinical studies
- Insurance coverage insights and cost breakdown for each system
- Reliability analysis based on 3,000+ verified user reviews
Detailed Reviews
In-depth analysis of each supplement
Dexcom G7
Most Advanced Features with Reliability Concerns
Key Ingredients
Key Benefits
- Predictive alerts warn 20 minutes before low blood sugar
- Share data with up to 10 followers (parents, caregivers)
- Fastest warm-up time (30 minutes)
- Apple Watch and smartphone integration
- Compatible with insulin pumps for automated insulin delivery
Considerations
- Sensors frequently fail at 7-8 days (not full 10 days advertised)
- 1 in 3 sensors falls off due to adhesive failure
- Inaccurate readings and constant false low alerts reported
- Poor customer service with hours-long hold times
- Recent product recalls with unreachable support
- Replacement sensors take 3-5 days despite 'overnight' promise
FreeStyle Libre 3
Real-Time CGM with Sensor Reliability Issues
Key Ingredients
Key Benefits
- Real-time glucose readings every minute
- No fingersticks required for calibration
- Fastest sensor warm-up (60 minutes)
- Good accuracy when sensors work properly (7.8% MARD)
- Smaller sensor size than competitors
Considerations
- Only 1 in 4 sensors lasts full 14 days according to user reports
- Frequent sensor failures and adhesive issues
- Dangerous false readings reported (showed 40 when actually 251)
- Poor customer service response times
- Expensive replacements (£50+ per sensor)
- Insurance prior authorization often required
Guardian Connect
FDA-Approved CGM with Moderate Performance
Key Ingredients
Key Benefits
- FDA-approved standalone CGM system
- Predictive low glucose alerts up to 60 minutes in advance
- Compatible with Medtronic insulin pumps
- Reliable customer service and support
- Good insurance coverage in many plans
Considerations
- Requires twice-daily fingerstick calibrations
- Longer warm-up time (2 hours) compared to competitors
- Lower accuracy (9.1% MARD) than Libre or Dexcom
- 7-day sensor wear shorter than alternatives
Side-by-Side Comparison
Compare key features across all supplements
MARD Accuracy
Sensor Duration
Warm-Up Time
Calibration Required
Monthly Cost
Data Sharing
User Rating
Common Questions
Quick answers to help you decide
User Experiences
Hear from actual supplement users
“While it requires calibration, Guardian Connect offers reliable performance and excellent customer support. Good choice for patients who want predictability over cutting-edge features. The 60-minute predictive alerts are genuinely helpful.”
The Bottom Line
While CGM technology represents a significant advancement in diabetes management, current systems face real-world reliability challenges that prospective users should carefully consider. The low user ratings reflect genuine issues with sensor longevity and customer support rather than problems with the underlying technology.
For Type 1 diabetes or intensive insulin management, a CGM is nearly essential despite these challenges. Guardian Connect emerges as the most reliable option with better customer service, though it requires daily calibrations. For those prioritizing accuracy and willing to accept reliability risks, FreeStyle Libre 3 offers the best MARD (7.8%) at a lower cost point.
Always maintain a backup fingerstick meter regardless of which CGM you choose, and verify your insurance coverage thoroughly before purchasing.