Is a 28-day Continuous Glucose Sensor (CGS) prescription with 2 dispensed and 3 refills appropriate for managing diabetes?

CGM Prescription Appropriateness: 28-Day Duration with 2 Dispensed and 3 Refills

Yes, this prescription is appropriate and aligns with standard CGM sensor wear duration, providing approximately 4 months of continuous monitoring coverage (2 sensors × 28 days = 56 days initially, plus 3 refills × 2 sensors × 28 days = 168 additional days). 1

Prescription Components Analysis

Duration: 28 Days

• Most current CGM sensors are FDA-approved for 10-14 day wear periods, not 28 days 1
• The 28-day duration likely represents a monthly supply period rather than individual sensor wear time
• Common sensor wear durations include:
  • 10 days for Dexcom G6/G7 systems 1
  • 14 days for FreeStyle Libre systems 1
  • 7-14 days for professional CGM devices 1

Quantity: Dispense 2 Sensors

• Dispensing 2 sensors for a 28-day period is standard for 14-day wear sensors (2 sensors × 14 days = 28 days) 1
• For 10-day sensors, this would provide 20 days of coverage, requiring adjustment to 3 sensors per 28-day period 1

Refills: 3 Times

• Three refills provide 4 months total coverage, which is clinically appropriate for ongoing CGM therapy 1
• Guidelines emphasize that CGM benefits correlate with ongoing consistent use, making continuous access essential 1
• Persons successfully using CGM should have continued access across third-party payers 1

Clinical Appropriateness Considerations

Patient Selection Criteria

This prescription is appropriate if the patient meets guideline-recommended indications 1:

Type 1 Diabetes:

• All adults and children with type 1 diabetes capable of daily CGM use 1
• Particularly those on intensive insulin therapy (≥3 injections daily or insulin pump) 1

Type 2 Diabetes:

• Patients on basal insulin or multiple daily injections 1
• Those with unexplainable hypoglycemia, nocturnal hypoglycemia, or hypoglycemia unawareness 1
• Patients with dramatic glycemic variability despite therapy 1
• Those with HbA1c above target not responding to multidrug therapy 1

Special Populations:

• Gestational diabetes and women with diabetes during pregnancy 1

Required Support Elements

The prescription should be accompanied by 1:

• Intensive diabetes education and training for optimal CGM implementation 1
• Ongoing support for continued device use 1
• Patient willingness and capability to learn device mechanics 1

Common Pitfalls to Avoid

Sensor-Specific Considerations

• Verify the specific CGM system prescribed matches the 28-day supply calculation 1
• For 10-day sensors (Dexcom): adjust quantity to 3 sensors per 28-day period 1
• For 14-day sensors (FreeStyle Libre): 2 sensors per 28-day period is correct 1

Insurance and Access Issues

• Confirm insurance coverage before dispensing, as reimbursement varies 1
• Cost considerations may impact access to specific CGM systems 1
• Guidelines recommend continued access for successful users across payers 1

Clinical Monitoring Requirements

• Some CGM systems require confirmatory fingerstick blood glucose for treatment decisions 1
• Two FDA-approved systems (Dexcom G5 and G6) allow decision-making without confirmatory SMBG 1
• Calibration requirements vary by device and should be clearly communicated 1

Contraindications to Note

• CGM is NOT recommended in intensive care units due to factors affecting accuracy (edema, vasoconstrictors, hypotension) 1
• Patients on peritoneal dialysis should avoid glucose oxidase-based sensors due to icodextrin interference 2
• Patients unwilling to learn device mechanics are poor candidates 1

Prescription Optimization

To ensure optimal outcomes 1:

• Specify the exact CGM system (e.g., "Dexcom G6" or "FreeStyle Libre 2") rather than generic "CGM sensor"
• Adjust quantity based on specific sensor wear duration
• Include instructions for sensor application frequency (e.g., "Apply new sensor every 10 days")
• Document medical necessity and patient education completion for insurance purposes 1