How do I write a prescription for the Freestyle Libre 3 (flash glucose monitoring system) sensor?

Prescribing FreeStyle Libre 3 Sensor

To prescribe the FreeStyle Libre 3 sensor, write "FreeStyle Libre 3 sensors, quantity 2 per month, with 1 reader device (if needed), refills for 12 months."

Understanding FreeStyle Libre 3 System

The FreeStyle Libre 3 is an intermittently scanned continuous glucose monitoring (isCGM) system, also known as "flash" glucose monitoring. This technology offers several advantages over traditional self-monitoring of blood glucose (SMBG):

• Factory calibrated - no fingerstick calibration required
• Sensor worn for up to 14 days
• Real-time glucose values with trend arrows when scanned
• Lower direct costs compared to real-time CGM systems
• Covered by most commercial insurance carriers and eligible Medicare programs 1

Key Components of the Prescription

1. Device name: Specify "FreeStyle Libre 3 sensors"
2. Quantity: Standard is 2 sensors per month (each sensor lasts 14 days)
3. Reader device: Include "with 1 reader device" for new users (if they don't already have one)
4. Duration: Specify refills (typically for 12 months)

Patient Selection for FreeStyle Libre 3

The FreeStyle Libre 3 is particularly beneficial for:

• Patients with type 1 diabetes
• Patients with type 2 diabetes on intensive insulin therapy
• Individuals with frequent hypoglycemia or hypoglycemia unawareness
• Patients requiring frequent glucose testing 1

Clinical Evidence Supporting Use

Studies show that FreeStyle Libre has excellent accuracy compared to SMBG, with mean absolute relative difference (MARD) reported by the manufacturer at 9.4% 1. Independent studies have found:

• Overall MARD of 12.8%, comparable to other CGM systems 2
• Accuracy varies slightly throughout sensor life, with best accuracy during days 5-7 2
• High user satisfaction and low adverse events 3
• Reduction in hypoglycemia risk in patients with type 1 diabetes 1

Practical Considerations

Sensor Placement

While the upper arm is the standard FDA-approved location, research shows the sensor can maintain clinical accuracy when placed on alternative sites like the chest or lower back if needed 4. The arm and chest sites are generally preferred by patients.

Patient Education

Ensure patients understand:

• The sensor requires a 1-hour start-up time after activation 1
• The system measures glucose every minute and records measurements every 15 minutes
• Data can be viewed by scanning with a reader or compatible smartphone
• Unlike real-time CGM systems, the FreeStyle Libre 3 does not have automatic alarms 1
• Capillary blood glucose testing should still be performed when hypoglycemia is suspected or when symptoms don't match readings 1

Pediatric Use

For pediatric patients (age 4-18 years), be aware that:

• The system is approved for children aged >4 years
• Studies show reasonable agreement between sensor glucose readings and capillary blood glucose measurements
• There may be greater interindividual variability in children
• Special attention to sensor attachment is needed to prevent early detachment 5

Common Pitfalls to Avoid

1. Not specifying the correct version: Ensure you specify "FreeStyle Libre 3" rather than just "FreeStyle Libre"
2. Inadequate quantity: Prescribe enough sensors for continuous use (2 per month)
3. Forgetting the reader device: New users will need a reader if they don't plan to use a smartphone app
4. Failing to provide education: Patients need proper training on sensor application, scanning technique, and data interpretation 1
5. Ignoring limitations: Be aware that accuracy may be lower at very high or very low glucose levels 1

By following these guidelines, you can properly prescribe the FreeStyle Libre 3 system to help patients improve their glucose monitoring and diabetes management.