What is the procedure for refilling the Freestyle Libre (continuous glucose monitoring system) sensor?

FreeStyle Libre Sensor Prescription and Refill Protocol

To refill a FreeStyle Libre continuous glucose monitoring sensor, prescribe "FreeStyle Libre sensor, apply one sensor every 14 days to back of upper arm, scan as needed for glucose monitoring" with appropriate refills. 1

Prescription Components

• Device name: FreeStyle Libre sensor
• Application instructions: Apply one sensor every 14 days to back of upper arm
• Usage instructions: Scan as needed for glucose monitoring
• Quantity: Typically 2-3 sensors per month (depending on insurance coverage)
• Refills: As appropriate for patient needs (usually 3-6 months)

Patient Selection Criteria

FreeStyle Libre is indicated for patients with:

• Type 1 diabetes on multiple daily injections or insulin pump therapy
• Type 2 diabetes on basal insulin or multiple daily injections
• Patients with specific clinical needs such as:
  • Unexplainable severe hypoglycemia
  • Recurrent hypoglycemia or asymptomatic hypoglycemia
  • Nocturnal hypoglycemia
  • Hypoglycemia unawareness 1

Insurance Coverage Considerations

• Medicare Part B covers CGM devices and supplies for beneficiaries with diabetes requiring intensive insulin management
• Documentation confirming diabetes diagnosis and need for intensive insulin management is required
• Medicare specifically covers therapeutic CGM devices that are FDA-approved for making treatment decisions without confirmatory fingerstick testing 1

Special Considerations

• Kidney disease: Add "Use with caution, confirm readings with fingerstick testing when making treatment decisions" for patients with chronic kidney disease 1
• Peritoneal dialysis: FreeStyle Libre is contraindicated for patients on peritoneal dialysis due to potential interference with glucose measurements 1
• Hemodialysis patients: Consider adding "Use for pattern recognition rather than specific glucose values" 1

Sensor Performance Awareness

• Sensor accuracy varies throughout its 14-day lifespan, with slightly reduced accuracy on days 1 and 14 2
• The sensor is most accurate during days 5-7 with a mean absolute relative difference (MARD) of 7.8% compared to 14.5% on days 0-1 and 14.7% on days 13-14 2
• The sensor should be applied to the back of the upper arm for optimal accuracy, as alternative sites like the chest or back may show reduced accuracy during rapid glucose changes 3

Follow-up Recommendations

• Schedule follow-up within 2-4 weeks of initial prescription to review data and adjust insulin regimen as needed
• Assess adherence to sensor replacement schedule and proper scanning technique
• Regular review of CGM data is necessary to evaluate glycemic control 1

Common Pitfalls to Avoid

1. Incorrect application site: The sensor should be applied to the back of the upper arm for optimal accuracy. Alternative sites may have reduced accuracy during exercise or rapid glucose changes 3

2. Medication interference: High doses of vitamin C and salicylic acid may affect sensor accuracy 1

3. Failure to scan regularly: For complete 24-hour data capture, the sensor must be scanned at least every 8 hours 4

4. Reliance on sensor readings during exercise: The sensor shows diminished accuracy during exercise, with a median absolute relative difference of 22% overall and up to 36.3% during hypoglycemia 5

5. Misinterpreting glucose trends after meals: The FreeStyle Libre may show a slower rise in glucose levels during the first 45-60 minutes after meals compared to blood glucose measurements 6