What is the proper insertion technique for the DEXCOM (Continuous Glucose Monitoring System) 7 sensor using the SIG (Sensor Insertion Guide)?

Dexcom G7 Sensor Insertion Instructions

The Dexcom G7 sensor should be inserted subcutaneously on either the upper arm or abdomen using the integrated one-button auto-applicator, avoiding placement on the arm with arteriovenous fistulas or grafts in dialysis patients. 1

Approved Insertion Sites

Upper arm (posterior) is the preferred site with demonstrated accuracy (MARD 8.2% in adults, 8.7% in pregnancy) 2, 3

Abdomen is an alternative site with slightly lower but acceptable accuracy (MARD 9.1% in adults, 11.5% in pregnancy) 2, 3

Upper buttock may be used in pregnant women with demonstrated accuracy (MARD 11.2%) 3

Critical Placement Considerations for Special Populations

In patients with end-stage kidney disease or on dialysis:

• Never place the sensor on the same arm as an arteriovenous fistula or graft 1
• Blood draws, infusions, and blood pressure measurements are contraindicated in the AVF/AVG arm due to infection, clotting, and access damage risks 1
• Subcutaneous sensors placed just under the skin are preferred in this population 1
• Patients with advanced CKD have higher coagulopathy and bleeding rates (uremic platelet dysfunction) that may impact sensor function after insertion 1

Insertion Technique

The G7 uses a factory-calibrated, single-button auto-applicator that does not require fingerstick calibrations 1, 2

The sensor wire diameter has been progressively decreased since the G4 version to minimize trauma and improve accuracy over time 1

Proper training in sensor placement is paramount, especially in patients with advanced CKD 1

Sensor Performance Specifications

Wear duration: 10.5 days 2, 4

Overall accuracy: MARD 8.2% (arm) and 9.1% (abdomen) in adults with diabetes 2

Pregnancy accuracy: MARD 10.3% overall, with 83.2% of values in 70-180 mg/dL range within 15% of comparator 4

ICU accuracy: Mean RAD 16% (median 12%), slightly higher than outpatient labeling but clinically acceptable 5

Important Interference and Safety Considerations

The G7 sensor has reduced susceptibility to acetaminophen interference compared to earlier versions due to a perm-selective membrane coating that inhibits diffusion of pharmacologic spurious signals 1

Acetaminophen 1g doses produce minimal interference (mean 3.1 ± 4.8 mg/dL) in G6/G7 systems 1

Patients must be educated on potential interfering substances including high doses of acetaminophen, salicylic acid, and ascorbic acid 1

Skin reactions should be assessed and addressed to aid successful device use 1

Documentation Requirements

CGM must continuously measure glucose and display data in real-time >95% of the time for the duration specified in the product label 1

The sensor should be scanned or transmit data continuously to avoid gaps, with data skips not exceeding 30 minutes at a time 1

Comprehensive reports with validation of glucose values should be documented in electronic health records 1

Common Pitfalls to Avoid

Do not place sensors in areas with poor subcutaneous tissue or over bony prominences, as accuracy may be compromised 1

Avoid relying solely on CGM for insulin dosing decisions in ICU settings until further validation studies confirm nonadjunctive use is safe 5

Temperature, humidity, and altitude may alter glucose readings, and most monitors will show an error if temperature is unacceptable 1

The G7 sensor survival rate is 90.3% at 10 days, indicating some sensors may fail before the full wear period 4