The Dexcom G7 is a small, wearable continuous glucose monitor that reads your glucose levels every five minutes and sends the data to your phone or receiver. Setting it up takes about two minutes, and the sensor requires no fingerstick calibration. Here’s how to get it on, paired, and working reliably for the full wear period.
Where to Place the Sensor
For adults 18 and older, the back of the upper arm is the only approved site for both the standard 10-day sensor and the newer 15-day sensor. For children ages 2 through 17, the back of the upper arm is also approved, and children ages 2 to 6 can additionally use the upper buttocks.
Pick a spot with enough subcutaneous fat to avoid hitting muscle. Avoid areas where clothing, seatbelts, or bag straps will rub or press against the sensor. You should also rotate to a different spot each time you apply a new sensor, which helps both your skin and the adhesive perform better.
Preparing Your Skin
Good skin prep is the single biggest factor in keeping your sensor stuck for the full wear period. Start by washing the site with soap and water and letting it dry completely. Then scrub the area with an alcohol wipe and wait at least 10 seconds for it to air dry. Don’t blow on it or pat it dry, as that can leave oils or lint behind.
If you have adhesive residue left from a previous sensor, remove it first with an adhesive remover product before cleaning. For people whose sensors tend to peel early, applying a skin adhesive like SkinTac or Mastisol under where the patch will sit can help significantly. Just avoid the small center area where the needle inserts.
Applying the Sensor
Wash and dry your hands before handling the applicator. Unscrew the cap and set it aside without touching the inside of the applicator.
Press the applicator firmly against your prepared skin and hold it there for 30 to 60 seconds before pushing the button. This pre-hold helps the adhesive bond to your skin before the needle fires. When you’re ready, push the button. You’ll feel a quick pinch as the thin filament inserts just under the skin.
Immediately after insertion, rub firmly around the entire adhesive patch three times. Using the back of your fingernail adds extra pressure and helps smooth out wrinkles. Then press gently on the sensor body itself for about 10 seconds.
Using the Overpatch
Each sensor comes with an overpatch, a thin adhesive ring that sits over the sensor’s existing patch to reinforce it. Peel off the clear liners one at a time without touching the white adhesive. Use the colored tab to position it around the sensor (a mirror helps if it’s on the back of your arm), then rub around the overpatch to secure it. Pull off the colored liner using the tab and rub around it once more.
If your skin tends to be oily or you sweat a lot, apply the overpatch right after inserting the sensor. If your skin is drier, you can wait and apply it only if the patch edges start to lift. Either approach works.
Warmup and Pairing
After you apply the sensor, open the Dexcom G7 app on your phone and follow the prompts to pair via Bluetooth. The standard 10-day sensor has a 30-minute warmup period, during which the sensor calibrates itself to your body’s interstitial fluid. The 15-day sensor uses a different algorithm and requires a 60-minute warmup. You won’t receive any glucose readings until warmup completes.
If you’re inserting a new sensor before bed, make sure the warmup finishes before you fall asleep. This ensures the sensor is reading properly and your alerts are active overnight.
Setting Up Alerts
The G7 offers customizable alerts for high glucose, low glucose, and an “Urgent Low Soon” predictive alert that warns you before you actually drop to a dangerous level. To adjust these, go to Profile, then Alerts in the app. For each alert type, you can change the glucose threshold that triggers it, choose between sound and vibration, and set a snooze duration so the same alert doesn’t fire repeatedly.
There’s also a “Delay 1st High Alert” feature, which can prevent unnecessary alerts after meals when a temporary spike is expected. Talk with your care team about whether that setting makes sense for your situation.
If you need quiet, Vibrate Quiet Mode converts all alerts to vibration only. You can set it for up to 6 hours or leave it on indefinitely.
Using Direct to Watch
The G7 can send glucose data directly to an Apple Watch without needing your iPhone nearby. This is useful during exercise, swimming, or any time you’d rather leave your phone behind. Compatible models include the Apple Watch Series 6 through Series 10, SE (2nd generation), Ultra, and Ultra 2, all running watchOS 10 or later.
Keeping the Sensor On for the Full Wear Period
The standard sensor lasts 10 days, and the 15-day sensor lasts 15, with an additional 12-hour grace period at the end of each so you have flexibility when scheduling your next change. A few placement tips make a real difference in adhesion over that stretch:
- Avoid skin folds and hair. Place the sensor where skin stays flat when you bend, twist, or reach. Shaving or trimming the area beforehand helps the adhesive grip.
- Stay dry early on. After applying a new sensor, give the adhesive time to fully bond before sweating, showering, or swimming. Skin types vary, but an hour or two of dry time helps.
- Keep it away from waistbands. Friction from clothing edges is one of the most common reasons sensors peel early.
Fixing Signal Loss
A “Signal Loss” message means your phone or receiver has lost the Bluetooth connection to the sensor. Most of the time, this resolves quickly with a few steps. First, bring the Dexcom app to the foreground on your phone. Don’t swipe-close the app; it’s designed to run continuously in the background.
Toggle Bluetooth off, wait a few seconds, then turn it back on. Keep your phone within about 20 feet of the sensor with as few obstructions as possible, including your own body. Bluetooth works best when the phone and sensor are on the same side of your body and have a clear line of sight. Make sure your phone battery is at least 20%.
If none of that works, restart your phone entirely. If signal loss persists for more than 30 minutes, contact Dexcom support through the app by going to Profile, then Contact.
Calibration
The G7 does not require fingerstick calibrations. The sensor is factory-calibrated, so it starts delivering readings as soon as warmup completes without any blood glucose meter input. You still have the option to enter a fingerstick calibration manually through the app if your readings seem off, but for most users this is never necessary.