Freestyle Libre vs Dexcom: Choosing the Right CGM for You
Continuous glucose monitoring (CGM) has transformed diabetes management — but with Freestyle Libre and Dexcom both offering multiple versions, choosing the right system can feel overwhelming. This guide breaks down the key differences so you can make an informed decision.
What Is a CGM?
A continuous glucose monitor consists of a small sensor worn on the skin (usually the upper arm or abdomen) with a tiny filament inserted just beneath the surface into the interstitial fluid. It measures glucose levels in the fluid every few minutes, transmitting data to a reader device or smartphone app. This gives a continuous, real-time picture of glucose rather than the isolated snapshots of finger-prick testing.
Freestyle Libre 2
The Freestyle Libre 2 is a flash glucose monitoring system available without a prescription in the UK. Key features: 14-day sensor wear, optional glucose alarms (high and low thresholds), data visible via LibreLink app on compatible smartphones or the dedicated reader. Accuracy: Mean Absolute Relative Difference (MARD) of approximately 9.2%. Available on NHS prescription for many Type 1 and eligible Type 2 patients, and purchasable directly from Chemist 2 Customer.
Freestyle Libre 3
The Libre 3 is the latest generation — significantly smaller (the size of two stacked 10p coins), with continuous real-time readings sent every minute to a smartphone without needing to scan. It offers improved accuracy and a more streamlined experience. Compatible with the LibreLink app and some automated insulin delivery systems.
Dexcom G6
The Dexcom G6 is a fully real-time CGM — unlike early Libre versions, it doesn’t require scanning. It wears for 10 days and sends readings automatically every 5 minutes to a compatible smartwatch, smartphone or receiver. It is approved for insulin dosing without confirmatory finger-prick tests. Key strength: integration with closed-loop (“artificial pancreas”) systems such as Omnipod 5 and Tandem t:slim X2.
Dexcom G7
The G7 is Dexcom’s latest, smallest device — a single-piece, all-in-one sensor and transmitter. It features a 10-day wear period plus a 12-hour grace period, 30-minute warm-up time (vs 2 hours for G6), improved accuracy and enhanced integration capabilities. A strong choice for those using closed-loop systems.
Side-by-Side Comparison
| Feature | Libre 2 | Libre 3 | Dexcom G6 | Dexcom G7 |
|---|---|---|---|---|
| Sensor wear | 14 days | 14 days | 10 days | 10+1 day |
| Real-time? | Scan required | Yes (every min) | Yes (every 5 min) | Yes (every 5 min) |
| Warm-up | 60 min | 60 min | 2 hours | 30 min |
| Alarms | Optional | Yes | Yes | Yes |
| Closed-loop | Limited | Some | Full | Full |
Which Is Right for You?
For most people on budget: Freestyle Libre 2 offers excellent value with good accuracy and 14-day wear. For real-time alerts and closed-loop systems: Dexcom G7. For Type 1 using insulin pumps: Dexcom is the stronger choice. For Type 2 or newly diagnosed: Libre 2 is a great starting point.
Shop Freestyle Libre sensors at Chemist 2 Customer. VAT relief available — see VAT Relief Guide. Related: Blood Glucose Monitoring Guide.