FINGER PRICK & CGM
How the two main ways to check work — and how CGMs and pumps team up.
There are two main ways to check your blood sugar: the traditional finger prick and the newer continuous glucose monitor (CGM). Both have their pros and cons — and modern systems often combine them. Knowing how each works helps you feel more confident and in control.
Finger prick
The classic method — quick, accurate, and a reliable backup.
🩸 How it works
You measure the capillary blood-sugar level using a glucometer (a small device that reads a drop of blood on a test strip).
Walk-throughs:
Continuous Glucose Monitors
Small wearable sensors that read your levels continuously and send the numbers to a phone, watch, or receiver.
✅ Why people use a CGM
- Reduces the need for most finger pricks.
- Sends alarms if blood sugar runs too high or too low.
- Safe and reliable.
- Often used together with insulin pumps.
🩸 Why finger pricks still matter
- Some CGMs need regular calibration.
- Confirm a reading if it doesn’t match how you feel.
- Sensors can occasionally fail or fall off.
Types of CGM
Two main families — the line between them is getting blurrier with newer models.
🔄 Real-time / continuous (rtCGM)
- Sends continuous updates about blood-sugar levels.
- Connects to a receiver, smartwatch, or smartphone.
- Allows sharing data with your medical team.
- Includes alerts and alarms for highs and lows.
📲 Intermittently scanned (isCGM / “flash”)
- Older versions need you to scan the sensor with a phone or reader.
- Newer models stream readings automatically, like rtCGM.
- Can also share data with your medical team.
- Most newer versions include alerts and alarms.
CGM & insulin pump combinations
Different ways CGMs and pumps work together.
📝 Sensor-augmented therapy (SaT)
- A CGM is used alongside manual insulin injections.
- You decide on doses based on the readings.
- For more on the medications themselves, see Chapter 12: Insulin & Medication.
🔗 Sensor-augmented pump (SaP)
- A CGM is used alongside an insulin pump.
- Usually paired with a continuous (rtCGM) sensor.
- Some systems can pause insulin delivery if levels run too low.
🧩 Sensor-integrated pump (SiP)
- The CGM is integrated directly into the pump.
- Insulin delivery can adjust based on readings.
- Usually paired with a continuous (rtCGM) sensor.
- Some systems can pause insulin delivery if levels run too low.
🤖 Hybrid closed-loop (HCL)
- Sometimes called automated insulin delivery (AID) systems.
- A continuous CGM is linked to an insulin pump.
- The pump automatically adjusts insulin based on CGM readings.
- Still needs some user input (e.g., carb amount at meals).
- Can be set for different situations like sleep or exercise.
A reminder on devices
Tech helps a lot — but you’re still the one steering.
🔔 You stay in the loop
Even the most automated systems still need you to watch for alerts, enter carbs at meals, and respond when something’s off. For more on this, see Chapter 17: Blood Glucose Monitoring.