CLOSING THE LOOP

The sensor drives the insulin pump

In automated insulin delivery, the CGM's readings feed an algorithm that adjusts how much insulin an insulin pump gives. That makes the sensor part of a control system, not just a display.

When a sensor drives dosing, its accuracy and reliability matter even more.

TODAY'S SYSTEMS

Sensor plus pump plus algorithm

The idea Often called a hybrid closed loop, where the system adjusts background insulin and the user still announces meals

Examples Tandem's Control-IQ, Insulet's Omnipod 5, and Medtronic's MiniMed 780G

Sensors Different systems pair with different CGMs

The CGM is the sense organ of an artificial pancreas.

SENSORS FOR EVERYONE

Over-the-counter CGMs

In 2024 Dexcom's Stelo and Abbott's Lingo became the first CGMs cleared for sale without a prescription, for adults who do not use insulin. They aim to help people see how food, sleep, and exercise affect their glucose.

A medical sensor is becoming a consumer health product.

WHAT'S NEXT

Where the technology is heading

Longer wear From a week or two toward a month or even a year

Smaller and cheaper More integrated, lower-cost sensors

More analytes Multi-sensor designs that add ketones or lactate are in development

Better accuracy Less drift and faster response

The same core idea is being pushed in every direction at once.

A CHECKLIST

How to judge a sensor claim

Accuracy What is the MARD, and how was it measured?

Wear and warm-up How long does it last, and how long until readings are trustworthy?

Interference What substances can change the reading?

Calibration and lag Is it factory calibrated, and how fast is the update rate?

Fit Does it work with the devices you use, and what does it cost?

You now know enough to ask the right questions about any glucose sensor.

UNIT 17 STUDY COMPLETE

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Ready for the Fab Challenge?

You've covered closed-loop insulin delivery, consumer CGMs, and how to judge a sensor's claims.