Continuous glucose monitoring

A diabetes monitoring system in which a thin sensor placed under the skin measures glucose in the interstitial fluid every few minutes and transmits the values to a smartphone, receiver, or insulin pump.

Indication

• Type 1 diabetes (especially in children, adolescents, and pregnant patients)
• Type 2 diabetes treated with multiple daily insulin doses or an insulin pump
• Frequent or unrecognized hypoglycemia (low blood sugar)
• Patients struggling to reach HbA1c targets (typically <7%)
• Gestational diabetes or monitoring of type 1/2 diabetes during pregnancy
• Patients planned for insulin pump integration (sensor-augmented pump or closed-loop / artificial pancreas systems)

Preparation

• The sensor application area (most often the back of the upper arm or the abdomen) is kept clean and dry
• Skin is cleared of moisturizers, creams, or oils; if needed, the applier wipes the area with an alcohol swab
• The sensor area should be free of tattoos, wounds, lipohypertrophy (insulin injection lumps), or infection
• The device educator provides training on the CGM brand, calibration (if required), and alarm settings
• If integrated with an insulin pump, sensor compatibility with the pump manufacturer is confirmed in advance

How it's performed

1. The sensor is placed under the skin as a thin filament using a factory-prepared applicator; the procedure takes a few seconds and is generally only mildly uncomfortable
2. The sensor is secured with adhesive tape on the back of the upper arm, abdomen, or the chosen site
3. The sensor pairs with a transmitter or single-piece device; readings are sent to the receiver/smartphone every 1-5 minutes
4. Some systems require a warm-up period in the first hours, during which readings are not displayed
5. Target glucose range (typically 70-180 mg/dL) and low/high alarm thresholds are individualized by the physician
6. When integrated with an insulin pump, features such as automatic basal adjustment or insulin suspension during hypoglycemia may be activated based on CGM data

Post-procedure

• At the end of the sensor wear period (7-14 days depending on brand), the sensor is replaced; rotation of application sites is recommended
• Time in Range (time spent within the target range, ideally >70%), HbA1c, average glucose, and variability reports are reviewed by the physician every 1-3 months
• Insulin doses, nutrition, and exercise plans are updated based on CGM data
• If skin reactions occur (redness, itching), a different tape or site is tried; protective skin products may be used if needed
• In pump-integrated systems, software updates and personalized settings are reviewed regularly

Risks

• Temporary pain, redness, itching, or allergic tape reaction at the sensor application site
• Rare skin infection
• Inaccurate sensor readings or delayed measurement (especially during rapid glucose changes)
• Over-reliance on alarms and skipping fingerstick verification when needed
• In pump-integrated systems: connection loss, sensor malfunction, or incorrect automated decisions

FAQ

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