Glucose sensors with and without a medical prescription

A sensor available on medical prescription is a continuous glucose monitoring (CGM) device that you can obtain only after a doctor recommends it through a prescription or another form of official medical recommendation. This category includes the sensors designed for managing diabetes, especially when you use insulin or other medicines that can lower your glucose a lot; these sensors have alarms that warn you when glucose rises or falls into dangerous zones [1].

The requirement for a prescription exists because these devices guide important treatment decisions, such as adjusting insulin doses, and the doctor checks whether the sensor suits your situation and explains how to use it. In many countries the prescription also opens the way to reimbursement of the cost through the health system or through insurance, so it is not a mere formality, but links the sensor to the medical and financial support that helps you use it safely [2].

A sensor available without a medical prescription (often called over-the-counter, or OTC) is a continuous glucose monitoring device that you can buy directly, without a doctor's recommendation; it is a recently emerged category, the first sensors of this kind becoming available in 2024 [1]. It is aimed mainly at people who do not use insulin — patients with type 2 diabetes controlled through oral medicines or diet, people with prediabetes, or those simply interested in how food and movement affect their glucose [3].

The feature that sets it apart the most is the absence of alarms for low or high glucose, and this is not an oversight but a deliberate choice, because these sensors are meant for people not exposed to the risk of severe hypoglycemia. You buy them online or from a pharmacy and connect them to a phone app, and in general they are not reimbursed by medical insurance, being considered consumer products [1].

Among the sensors available on prescription, the best known internationally are the FreeStyle Libre family (Libre 2 Plus and Libre 3 Plus), Dexcom One Plus and G7, the Medtronic sensors (Guardian and Simplera) and the implantable Eversense sensor; they all have alarms, and many can be used in automated insulin delivery systems [4].

Among the sensors available without a prescription, Dexcom Stelo, Abbott Lingo and Abbott Libre Rio stand out: Stelo and Libre Rio are aimed at adults with type 2 diabetes who do not use insulin, while Lingo is positioned as a wellness tool for tracking glucose. An important aspect is that the availability of these products differs greatly from one country to another, so a sensor sold without a prescription in one place may require a prescription in another, or may be missing entirely [1].

Yes, in regions where non-prescription sensors are available, you can buy a glucose sensor without seeing a doctor. The non-prescription category was created precisely to offer direct access to people who want to understand their glucose without going through the medical system: you order online or buy from a pharmacy, then activate the sensor with an app [1].

However, the fact that you can buy it does not mean it is also the best choice for you. If you have type 1 diabetes or use insulin, a sensor without alarms can leave you exposed to dangerous drops in glucose that you may not notice in time, and even if you do not use insulin, a conversation with the doctor helps you choose the right device and correctly interpret what it shows you [2].

No, non-prescription sensors are not suitable for a patient with type 1 diabetes. The main reason is that these sensors have no alarms for glucose that is too low or much too high, and a patient with type 1 diabetes depends on insulin and is exposed at any moment to hypoglycemia, which can sometimes become severe rapidly and without symptoms; without a warning, you might not notice a dangerous drop during sleep or physical effort [5].

Beyond the missing alarms, non-prescription sensors are not approved to guide insulin doses and do not connect to insulin pumps. If you have type 1 diabetes you need a sensor available on prescription, one that warns you in real time, ideally able to integrate with an automated insulin delivery system and to give you data you can trust for treatment decisions; the lower cost of a non-prescription sensor cannot make up for the safety you lose [2].

A sensor that requires a medical prescription is obtained in a few steps: first you go to the doctor, who assesses whether the sensor is indicated and writes you the prescription, and with it you go to a pharmacy or a specialized supplier. In some health systems part of the cost or the entire cost is covered through reimbursement, but for this you usually need additional documents drawn up by the doctor [6].

The exact route differs from one country to another: in some places the pharmacy hands you the sensor directly, in others you order from a distributor authorized by the manufacturer, and sometimes only certain medical centers can issue these devices. The common element everywhere remains the prescription, because without it you cannot legally obtain a sensor in this category, and the doctor or the diabetes team can tell you exactly which channel works in your area [2].

No, a non-prescription sensor does not offer the same functions as one available on prescription. The most important difference is the absence of alarms: a non-prescription sensor shows you the values and trends of glucose, but does not warn you when it rises or falls too much, and in addition many non-prescription sensors update their value less often — for example every 15 minutes instead of every minute or 5 minutes — so you see the changes with a slight delay [1].

Other differences relate to connectivity and medical use: sensors available on prescription can connect to automated insulin delivery systems (closed-loop pumps), some can be approved for use in insulin dosing decisions and often allow data sharing with the family or the medical team in real time, while non-prescription sensors are meant for personal observation of trends, not for managing insulin treatment [7].

Yes, you can switch from a non-prescription sensor to one available on prescription, and in many situations this is in fact the right step. If you started with a non-prescription sensor out of curiosity or to track type 2 diabetes, but your situation changes — for example you start insulin treatment or the doctor finds that you need alarms — switching to a sensor available on prescription brings you the additional safety functions you need, after a consultation and a prescription [2].

The transition is not complicated, but it goes through a doctor, who assesses why you need a more advanced sensor, chooses together with you the model suited to your treatment and explains the differences in use; the experience gained with the non-prescription sensor helps you, because you are already used to wearing a sensor and reading the data. Switching in the opposite direction, from a sensor on prescription to one without, is rarely recommended, especially if you already use insulin, precisely because you would lose access to the alarms [5].

The doctor has several roles when you use a sensor available on prescription. First, the doctor can advise you which sensor is more suitable for your situation and writes the prescription that gives you access to it, then explains how to apply it, how to set the alarms and how to interpret what you see on the screen [2].

After that, the role becomes an ongoing one: the doctor periodically analyzes the data gathered by the sensor, such as the time spent in the target range and the glucose trends, and uses them to adjust your treatment, helps you solve practical problems (from skin reactions at the application site to situations where the value does not seem to match how you feel) and works together with you so that the sensor functions at its best [7].