Integrated CGM sensors (iCGM) and interoperability

An integrated glucose sensor, known as an iCGM (from “integrated continuous glucose monitoring”), is a type of sensor that automatically measures the concentration of glucose in the fluid beneath the skin, continuously, throughout the entire wear time. The term “integrated” indicates that this sensor was specially built to offer superior accuracy and precision and to communicate securely with other digital devices, such as an insulin pump or a phone. It is not just a device that shows you your glucose value, but a piece designed to fit, safely, into a larger system in which several devices work together [1].

What distinguishes an iCGM sensor from an ordinary one is that it has been verified under strict safety and accuracy rules, precisely because its data can be used directly for important decisions, such as automated insulin dosing. An iCGM sensor transmits the estimated glucose values to the connected devices, and you can trust that these values are safe enough to guide your treatment [2]. In this way, the sensor becomes the foundation on which modern insulin-delivery systems can be built.

Interoperability means the ability of a glucose sensor to connect and work correctly together with devices made by other manufacturers. An interoperable sensor sends the glucose values in a standardized way, so that an insulin pump or a compatible app can receive and use these data, even if they come from different companies. In practice, the sensor speaks a “common language” that the other devices also understand [1].

For you, as a person with diabetes, interoperability brings more freedom of choice. Instead of being forced to use all the devices from a single manufacturer, you can combine a sensor with a pump or with a phone app that suits you better. This flexibility allows the building of a personalized system, in which each piece is chosen for your needs, and the components can be swapped more easily when new versions appear [2].

To be classified as iCGM, a sensor must pass through a series of special checks, stricter than those required of an ordinary sensor, even a non-adjunctive one. These checks control how close the sensor's values are to the real glucose values, across the whole range of low and high values and throughout the entire wear time. The sensor is required to remain accurate both when glucose is low and when it is high, but also when glucose changes rapidly, and the data must come from studies carried out in a controlled, academic environment (which are missing in the case of many sensors with seemingly astonishing declared performance) [3] [4].

These special standards exist because an iCGM sensor can directly guide treatment decisions and can drive an automated insulin system. That is why, in addition to accuracy, the sensor must transmit the data in a secure and stable way to the connected devices, without losses or errors that could put the patient at risk. The level of accuracy required of an iCGM sensor is among the most demanding defined for such devices, precisely in order to protect the patient who relies on these values [1].

The main advantage of an integrated sensor is the flexibility to use it as part of a system in which several “integrated” devices work together. You can choose the components that suit you best and you can swap them when better versions appear, because an iCGM sensor can connect to pumps and to programs made by different manufacturers. This freedom of choice means that your system can be adapted to your needs, instead of being forced to accept a single fixed package [1].

A second important benefit comes from the high level of accuracy and safety that an iCGM sensor must reach. In this way, the integrated sensor gives you at the same time confidence in the values and the possibility of building a modern, personalized system [3].

The safest way to find out whether your sensor is an iCGM is to check the official product information, such as the label, the instructions for use or the description on the manufacturer's website. There it is stated whether the sensor has been classified as iCGM and whether it can be used to directly guide treatment decisions (a non-adjunctive sensor), without additional confirmation with the glucometer. Also, the fact that the sensor is announced as being compatible with pumps or automated systems from different manufacturers is an important sign that it is an integrated sensor [1].

If you are not sure after reading the product information, the best solution is to ask your medical team. They can confirm the type of your sensor and can explain to you which devices are compatible with it. It is useful to find this out because the type of the sensor tells you whether you can officially integrate it into a personalized automated insulin system or whether you can use it only within the manufacturer's ecosystem [2].

Yes, an iCGM sensor can also work on its own, without being connected to a pump or to an automated insulin system. In this mode, the sensor continuously estimates glucose and displays the values for you on a dedicated receiver or on the phone, just like any continuous monitoring sensor. In this way you can follow the evolution of glucose, you can see in which direction it is heading and you can receive alarms when the values become too low or too high, even if you are not using any other connected device. You can make treatment decisions because it is non-adjunctive, and you can have more confidence in the values it provides because it is an iCGM (a quality standard that is harder to achieve) [5].

What makes an iCGM sensor truly special is that it also has the possibility of being integrated into a larger system when you choose this. In other words, you can start by using it on its own, just to track your glucose, and later you can connect it to an interoperable pump or to a compatible algorithm. This dual possibility — of working both on its own and as part of a system — gives you the freedom to gradually build your own automated insulin-delivery system, at the pace that suits you [3].