The Dexcom G7 sensor is an all-in-one continuous glucose monitor worn on the back of the upper arm for up to 10 days plus a 12-hour grace period. The integrated device replaces the separate sensor-plus-transmitter design of the older Dexcom G6. After a 30-minute warm-up, it provides glucose readings every 5 minutes without any fingerstick calibration and sends data over Bluetooth to your phone or a Dexcom receiver.
What Is Inside the Sensor
The disposable G7 device contains:
- A flexible platinum-iridium filament coated with glucose oxidase, sitting 3 to 5 mm below the skin
- Miniature electronics that apply voltage and read current every 5 minutes
- A Bluetooth Low Energy radio for wireless transmission
- A small lithium battery sized for the 10-day life of the sensor
- A water-resistant (IP28) adhesive patch that holds the device against the skin
Unlike the G6, there is no separate transmitter clipping on top. Everything is integrated into one disposable unit.
Specs at a Glance
| Spec | Value |
|---|---|
| Wear time | 10 days + 12-hour grace period |
| Warm-up | 30 minutes |
| Calibration | None required (factory-calibrated) |
| Reading frequency | Every 5 minutes |
| Insertion site (adults) | Back of upper arm |
| Insertion site (children 2-6) | Upper buttocks |
| Water rating | IP28 (8 ft, 24 hours) |
| Bluetooth range | ~20 feet line-of-sight |
| Accuracy (MARD) | ~8 to 9% |
| Size | Approximately 0.6 inch diameter × 0.2 inch tall |
| Sensor code | 4-digit, printed on applicator |
How to Apply a G7 Sensor
- Wash the insertion site with soap and water; let dry completely.
- Remove the applicator from the sterile packaging.
- Peel the backing tab off the adhesive.
- Place the applicator on the back of your upper arm.
- Press firmly straight down against the skin until you feel and hear the button click.
- Press the button. The sensor inserts with a hidden needle, which retracts automatically.
- Hold in place for a moment, then lift the applicator away. Dispose of it in a sharps container.
- Note the 4-digit sensor code on the applicator.
- Open the Dexcom G7 app or receiver and enter the sensor code within 30 minutes.
- Wait 30 minutes for warm-up. Readings begin automatically.
G7 Sensor vs G6 Sensor
| Feature | Dexcom G6 | Dexcom G7 |
|---|---|---|
| Wear time | 10 days | 10 days + 12-hour grace period |
| Warm-up | 2 hours | 30 minutes |
| Separate transmitter | Yes (reusable, 90-day battery) | No — integrated into sensor |
| Size | Sensor + transmitter stack | About 60% smaller, all-in-one |
| Fingerstick calibration | Optional | Not supported (factory only) |
| Insertion sites (adults) | Abdomen, upper buttocks, back of arm | Back of upper arm only |
| Accuracy (MARD) | ~9 to 10% | ~8 to 9% |
How the Filament Measures Glucose
The glucose oxidase enzyme on the filament reacts with glucose in interstitial fluid, producing hydrogen peroxide. The peroxide is oxidized at a platinum electrode, generating a small current proportional to glucose concentration. The sensor electronics sample this current every 5 minutes, apply calibration algorithms and temperature compensation, and produce a plasma-equivalent glucose value. For the full mechanism and signal chain, see our guide on how Dexcom G7 works.
Interstitial vs Blood Glucose Lag
Interstitial fluid glucose tracks blood glucose with a 5 to 15 minute lag, especially when glucose is changing rapidly. During a post-meal rise or a sudden drop, a CGM reading may differ from a simultaneous fingerstick by 10 to 30 mg/dL. When glucose is stable, the two usually agree within 10 percent. This lag is why you should not treat a hypoglycemic episode based only on a rapidly falling CGM reading — if symptoms are present, treat, then verify with a fingerstick if possible.
Sensor Warranty and Replacement
- If a sensor fails before the 10-day mark (premature error, signal loss, falsely low readings), Dexcom typically replaces it
- Keep the applicator label or lot number handy for warranty claims
- Most replacements ship within 3 to 5 business days
- Repeated failures in one lot should be reported so Dexcom can investigate
Protecting Your Sensor
- Use an overpatch or medical tape if you sweat heavily or swim daily
- Avoid applying sunscreen, bug spray, or lotion directly over the adhesive
- When removing old adhesive, use an adhesive remover wipe rather than pulling harshly
- Prep skin carefully — some patients use a barrier wipe (Skin-Tac, Mastisol) to improve adhesion
- Avoid high-impact contact with the sensor (rubbing against car seats, doorframes)
- For MRI, CT with contrast, or X-ray of the arm, remove the sensor per medical staff instructions
Who Uses the G7
- Adults with type 1 or type 2 diabetes on intensive insulin therapy
- Children 2 years and older with diabetes
- Pregnant individuals with pre-existing or gestational diabetes
- Adults with type 2 diabetes not on insulin who meet specific Medicare or insurance criteria
- Some users with prediabetes or non-diabetic indications use Dexcom’s OTC Stelo product rather than the prescription G7
Related Reading
See our related guides on the G7 all-in-one design, G7 receiver, GMI on Dexcom G7, and the broader detection of prediabetes hub.
The Bottom Line
The Dexcom G7 sensor is a compact, disposable, all-in-one CGM worn on the back of the upper arm for up to 10 days plus a 12-hour grace period. It replaces the sensor-plus-transmitter design of the G6 with a single integrated device, cuts warm-up from 2 hours to 30 minutes, and maintains MARD accuracy around 8 to 9 percent. Apply it correctly, protect the adhesive, and understand the interstitial-blood lag — and it will give you a continuous, actionable view of your glucose for the whole wear period.
