What are the requirements for a patient with diabetes to use a continuous glucose monitoring (CGM) patch, such as Freestyle Libre (flash glucose monitoring system) or Dexcom G6, to monitor blood sugar levels and avoid finger stick testing?

Requirements for Continuous Glucose Monitoring (CGM) Patch Systems

All patients with type 1 diabetes should use CGM regardless of age or glycemic control, and type 2 diabetes patients on intensive insulin therapy (≥3 injections daily or insulin pump) should also use CGM to reduce hypoglycemia and improve glucose control. 1, 2

Primary Medical Indications

Type 1 Diabetes

• All type 1 diabetes patients qualify for CGM, including children, adolescents, and adults, regardless of current blood sugar control 1, 2
• Particularly indicated when not meeting glycemic targets, experiencing hypoglycemia unawareness, or having recurrent hypoglycemic episodes 1, 2

Type 2 Diabetes

• Intensive insulin therapy: Patients taking 3 or more insulin injections daily or using an insulin pump 3, 1
• Problematic hypoglycemia: Unexplainable severe hypoglycemia, recurrent hypoglycemia, asymptomatic hypoglycemia, or nocturnal hypoglycemia 3, 1
• Unexplained hyperglycemia, especially fasting hyperglycemia 3, 1
• Dramatic glucose variability despite regular finger-stick monitoring 3, 1
• Fear-driven high glucose: Patients who deliberately maintain high blood sugar due to fear of hypoglycemia 3
• Inadequate control: HbA1c above target despite multiple oral medications and/or non-insulin injectable therapies 3, 1

Pregnancy-Related Indications

• Gestational diabetes patients 3, 1
• Women with pre-existing diabetes during pregnancy 3, 1

Special Clinical Situations

• Diabetes with gastroparesis 3, 1
• Special types of diabetes with dramatic glycemic variability 3, 1
• Endocrine disorders with dramatic glycemic variability 3, 1

Critical Prerequisites for CGM Use

Patient Capability Requirements

• Willingness and ability to learn the device's mechanical operation - this is non-negotiable as optimal CGM requires ongoing education and learning 3, 1
• Commitment to near-daily use: Real-time CGM must be worn as close to daily as possible (≥6 days per week) for maximum benefit, as frequency of sensor use is the greatest predictor of HbA1c improvement 3, 1, 2
• For flash glucose monitoring (like Freestyle Libre): Must scan the sensor at minimum once every 8 hours to capture full 24-hour data 3, 2

Education and Training Requirements

• Robust diabetes education, training, and ongoing support are mandatory for optimal implementation 3, 1, 2
• Must understand how to interpret glucose trends, respond to alerts, and make treatment decisions based on CGM data 3, 1
• Ability to perform finger-stick blood glucose testing remains necessary for:
  • Calibration (for devices requiring it) 3
  • Verification when CGM readings don't match symptoms 3, 1
  • Confirmation before making treatment decisions during hypoglycemia 3

Device-Specific Considerations

• Real-time CGM (like Dexcom G6): Provides continuous glucose display, high/low alerts, and trend arrows; requires daily calibration for some models 3
• Flash glucose monitoring (Freestyle Libre): No calibration required, worn up to 14 days, but no automatic alerts; must be actively scanned 3

Important Contraindications and Limitations

Absolute Contraindications

• Intensive care unit patients: Skin edema, vasoconstrictor drugs, hypotension, hypoxemia, and high-dose acetaminophen adversely affect sensor accuracy 3, 1, 2
• Unwilling patients: CGM is not suitable for those unwilling to learn device operation, as success depends entirely on sustained use and proper data interpretation 3, 1

Technical Limitations to Understand

• 5-15 minute lag time: CGM measures interstitial fluid glucose, which lags behind blood glucose during rapid changes 1, 2
• Lowest accuracy during hypoglycemia: Critical limitation requiring finger-stick confirmation when low glucose is suspected 1, 2
• Medication interference: High-dose acetaminophen, ascorbic acid (vitamin C), and certain other medications can affect readings 2
• Environmental restrictions: Avoid strong magnetic fields, MRI, and in some devices conventional X-ray and CT scanning 1, 2
• Skin reactions: Irritation or allergy to adhesive should be assessed and addressed 1, 2

Practical Implementation Algorithm

Step 1: Verify Medical Indication

• Confirm diagnosis of type 1 diabetes (automatic qualification) OR
• Type 2 diabetes with intensive insulin therapy OR
• Type 2 diabetes with problematic hypoglycemia/hyperglycemia/variability 1, 2

Step 2: Assess Patient Readiness

• Evaluate willingness to learn technology 1, 2
• Confirm ability to commit to near-daily use 1, 2
• Assess capability to perform backup finger-stick testing 3, 1

Step 3: Provide Comprehensive Education

• Device insertion and maintenance 3
• Interpretation of glucose trends and alerts 3, 1
• When to confirm with finger-stick testing 3
• Recording diet, exercise, medication, and other glucose-related events 3

Step 4: Establish Ongoing Support

• Regular follow-up to review CGM data 3, 1
• Troubleshooting technical issues 1, 2
• Reinforcement of proper use techniques 3, 1

Common Pitfalls to Avoid

• Insufficient patient education: The most common reason for CGM failure is inadequate initial training and lack of ongoing support 3, 1, 2
• Relying solely on CGM without finger-stick backup: Always confirm with finger-stick when symptoms don't match CGM readings or during suspected hypoglycemia 3, 1
• Ignoring calibration requirements: For devices requiring calibration, enter blood glucose values immediately after obtaining the result during stable glucose periods (before meals, bedtime) 3
• Expecting immediate perfection: Benefits correlate directly with adherence over time; initial adjustment period is normal 1, 2