What are the usage guidelines for the Freestyle Libre 3 Plus (flash glucose monitoring system) sensor?

FreeStyle Libre 3 Plus Sensor Usage Guidelines

The FreeStyle Libre 3 Plus sensor should be prescribed for continuous, routine use with each sensor worn for up to 14 days on the back of the upper arm, requiring scanning at minimum every 8 hours to capture complete glucose data, and should be replaced regularly without gaps in monitoring to maximize clinical benefit. 1

Device Characteristics and Technology

• The FreeStyle Libre system is a factory-calibrated intermittently-scanned continuous glucose monitoring (isCGM) device that does not require fingerstick calibrations 2
• The sensor uses wired glucose oxidase-based enzyme technology with a sensing membrane that operates at very low voltage, making it resistant to interference from acetaminophen and uric acid at therapeutic levels 2
• Interstitial glucose levels are measured continuously, but data are only available when the sensor is scanned with a reading device 2, 1

Proper Usage Instructions

Sensor Placement and Duration

• Insert the sensor on the back of the upper arm for wear periods of up to 14 days 3, 4
• When changing sensors, insert the new sensor before removing the old one to avoid gaps in data collection 1
• Patients should have uninterrupted access to CGM supplies to minimize monitoring gaps 1

Scanning Frequency

• Scan the sensor at minimum once every 8 hours to capture complete 24-hour glucose data 1, 5
• More frequent scanning is recommended for optimal glucose pattern recognition and insulin dose adjustment 6
• The device should be used "as close to daily as possible for maximal benefit" according to diabetes care standards 1

Accuracy Considerations

Overall Performance

• The system demonstrates 86.7% of sensor results within Consensus Error Grid Zone A, with an overall mean absolute relative difference (MARD) of 11.4% 4
• Accuracy remains stable throughout the 14-day wear period, though sensors are least accurate during the first and last days of use 7
• In pediatric populations (ages 4-17), the system shows 83.8% of results in Zone A with an overall MARD of 13.9% 3

Factors Affecting Accuracy

• Sensor accuracy is unaffected by patient characteristics including age, body mass index, sex, type of diabetes, insulin administration method, or HbA1c levels 3, 4
• Salicylic acid and ascorbic acid may affect sensor accuracy by reacting with the sensor's electrode 2
• The wired-enzyme technology reduces susceptibility to oxygen changes and electrochemical interferents 2

Critical Contraindications and Cautions

Dialysis Populations

• Do NOT use FreeStyle Libre sensors in patients receiving peritoneal dialysis due to lack of evidence regarding icodextrin interference 2
• Use with caution in hemodialysis patients, focusing on glucose patterns rather than specific values, as accuracy is reduced (mean amplitude relative difference of 19.5% overall, 31.9% for glucose <70 mg/dL) 2
• In hemodialysis patients, only 49-51% of glucose readings fall into acceptable error grid zones A and B 2

Chronic Kidney Disease

• In CKD stages 3-5, the system shows good correlation with HbA1c, though accuracy may be reduced in severe kidney disease 2

Common Pitfalls to Avoid

• Inconsistent use reduces clinical value and limits the technology's ability to improve quality of life and health outcomes 1, 5
• Failing to scan at least every 8 hours results in incomplete 24-hour data capture 1, 5
• Not replacing sensors regularly creates gaps in glucose monitoring that compromise diabetes management 1
• Relying on the device in peritoneal dialysis patients despite clear contraindications 2
• Using specific glucose values rather than patterns in hemodialysis patients where accuracy is compromised 2

Documentation Requirements

• Document sensor insertion site, scanning frequency, and any gaps in data collection 5
• Record alert settings for hypoglycemia and hyperglycemia if using real-time features 5
• Note any potential medication interferences, particularly high doses of acetaminophen, salicylic acid, or ascorbic acid 5
• Confirm that the CGM continuously measured glucose >95% of the time for the duration specified 5