CGM supplies include the sensor, transmitter, and a display device as core components, plus a range of skin-prep and adhesive products that most users end up needing. Whether you’re new to continuous glucose monitoring or helping someone get set up, here’s a full breakdown of everything involved.
The Three Core Components
Every CGM system has three basic parts that work together to track glucose levels around the clock.
The sensor is a tiny filament that sits just under your skin and measures glucose in the fluid between your cells. You insert it yourself using a spring-loaded applicator (included with each sensor). A small needle guides the filament into place, then retracts, leaving only the flexible sensor behind. Sensors are disposable. Depending on the system, they last anywhere from 7 to 15 days before you peel them off and apply a fresh one. The Dexcom G7, for example, lasts up to 10 days in its standard version and up to 15 days in the extended-wear version.
The transmitter sits on top of the sensor and wirelessly sends glucose readings to your phone or another display. This is where CGM systems differ the most. Some systems, like the Dexcom G6, use a separate reusable transmitter that snaps onto each new sensor. That transmitter’s battery lasts about 3 months before you need a replacement. Newer systems, like the Dexcom G7, build the transmitter directly into each disposable sensor as an all-in-one unit, so there’s no separate piece to track or replace.
The display device is whatever shows you your numbers. For most people, this is a smartphone app. You can also use a dedicated handheld receiver (a small standalone screen) or, if you use an insulin pump, the pump itself may display your glucose data. Smartwatch apps are available too, though they require a connected phone to relay the data.
Skin Preparation Supplies
The sensor sticks to your body with a medical-grade adhesive patch, and how well it holds depends largely on your skin prep. At minimum, you need the area to be clean and dry. Most people use an alcohol swab to remove oils before applying the sensor.
Beyond basic cleaning, many CGM users add barrier wipes or skin-prep solutions. These create a thin, tacky layer on the skin that does two things: improves adhesion so the sensor stays put for its full wear period, and acts as a protective barrier between the adhesive and your skin to reduce irritation. Popular options include products like Skin Tac wipes and similar adhesive barrier films. If you’re physically active, sweat heavily, or live in a humid climate, skin-prep wipes can make the difference between a sensor that lasts 10 days and one that starts peeling on day 3.
Overlay Patches and Adhesive Accessories
The adhesive patch that comes with each sensor works fine for some people, but many users find they need extra help keeping the sensor secure, especially during exercise, swimming, or hot weather. Overlay patches (also called overpatch or cover patches) are thin adhesive strips that go over the top of the sensor to hold everything in place. Some CGM manufacturers include a few free patches with each shipment, but most users buy them separately.
Under patches serve a different purpose. These go on your skin first, beneath the sensor’s adhesive. They create a barrier that protects sensitive skin from the adhesive, extends the sensor’s wear time, and makes removal easier at the end of the session. If you’ve noticed redness, itching, or rashes under your sensor, an under patch is typically the fix.
Removal Supplies
After 7 to 15 days of wear, the adhesive bonding a sensor to your skin can be stubborn. Adhesive remover wipes, sprays, or solutions dissolve the medical-grade glue so you can peel the sensor off without pain or skin trauma. They also clear away any sticky residue left behind, which matters because buildup from previous sensors can irritate the skin at your next application site. Brands like AllKare and Smith and Nephew make wipes specifically designed for medical adhesive removal.
Fingerstick Supplies for Calibration
Most current-generation CGMs are marketed as “factory calibrated,” meaning they don’t require routine fingerstick blood sugar checks to stay accurate. But the picture is more nuanced than that. CGM sensors measure glucose in the fluid between cells rather than in blood directly, and a simple calibration function converts those readings into blood glucose estimates. Older systems required fingerstick calibrations once or twice a day using a traditional blood glucose meter, test strips, and lancets.
Even with newer no-calibration systems, many users keep a basic glucose meter and test strips on hand. Readings can occasionally drift, especially in the first 24 hours after a new sensor insertion, and confirming a suspicious number with a fingerstick before making a treatment decision is standard practice. Dexcom’s own guidance notes that users should confirm readings on the app or receiver before making treatment decisions. A small meter kit with a few test strips is a reasonable backup supply to keep around.
What a Typical Resupply Looks Like
Once you’re up and running, most of your ongoing costs and orders center on replacement sensors. If your system has a separate transmitter, you’ll replace that roughly every 3 months. Beyond the core components, a typical resupply order for an active CGM user might include:
- Sensors: 2 to 4 per month, depending on wear duration
- Transmitter: 1 every 3 months (modular systems only)
- Skin-prep wipes: one per sensor application
- Overlay or under patches: one per sensor session if needed
- Adhesive remover wipes: one per sensor removal
- Alcohol swabs: one per sensor application for site cleaning
Sensors and transmitters are the prescription items, typically covered (at least partially) by insurance or Medicare. The skin-care accessories, patches, and adhesive removers are over-the-counter products you can buy from pharmacies, diabetes supply retailers, or online. They’re not expensive individually, but they add up, so it’s worth factoring them into your budget from the start.