The Dexcom G7 is only FDA-cleared for the back of the upper arm (ages 2 and older) and the upper buttocks (ages 2 to 6). The abdomen is not an approved wear site, even though many people wore earlier Dexcom models there. This isn’t an oversight. It comes down to accuracy differences between body locations and the regulatory path Dexcom chose for the G7.
Where You Can Wear the G7
For adults and children over age 2, the back of the upper arm is the only cleared location. Children between ages 2 and 6 also have the option of the upper buttocks, since small arms can make sensor placement difficult. The newer G7 15 Day sensor narrows things further: it’s approved only for the back of the upper arm in adults 18 and older.
If you’ve used a Dexcom G6 before, this feels like a step backward. The G6 was cleared for the abdomen in adults and for both the abdomen and upper buttocks in children ages 2 to 17. Many longtime users built their routine around stomach placement, so the switch to arm-only with the G7 is a real adjustment.
The Accuracy Gap Between Arm and Abdomen
Clinical trial data shows the G7 performs noticeably better on the arm than on the abdomen. In the pivotal study published in Diabetes Technology & Therapeutics, sensors worn on the arm had an overall mean error of 8.2% compared to a lab reference, while abdomen-placed sensors came in at 9.1%. That gap might sound small, but it shows up more clearly in other metrics.
When researchers looked at how many individual sensors met a strict accuracy threshold (at least 80% of readings falling within 20% of the lab value), 94.5% of arm sensors passed compared to 87.5% of abdomen sensors. That means roughly 1 in 8 abdomen sensors fell short of the accuracy standard, versus about 1 in 18 on the arm.
The difference was most pronounced on the first day of wear. Arm sensors started with an error rate of 11.9%, while abdomen sensors began at 12.9%. By the end of the sensor’s life (day 10.5), both improved, but the arm still held a clear lead: 6.9% error versus 8.8%. Abdomen sensors were consistently less accurate across every glucose range and every rate of glucose change measured in the trial.
Why the Arm Reads More Accurately
Continuous glucose monitors don’t measure blood sugar directly. They measure glucose in the fluid between your cells, called interstitial fluid. The relationship between that fluid and your actual blood sugar varies by body location, and it’s influenced by factors like local blood flow, fat distribution, tissue compression, and muscle activity.
The abdomen is more prone to interference from several of these factors. It has more variable fat thickness between people, which affects how deep the sensor filament sits in the tissue. It’s also subject to more compression from waistbands, seat belts, and sleeping positions, which can temporarily disrupt blood flow and produce false low readings. Exercise makes these differences worse. Research on continuous glucose sensors during aerobic activity found that abdominal placement produced readings biased low compared to actual blood glucose, roughly double the bias seen at other sites. Localized changes in blood flow and glucose use in the core during physical movement likely drive this effect.
The back of the upper arm, by contrast, has relatively consistent tissue depth across most body types, less mechanical compression in daily life, and less fluctuation in local blood flow during exercise. It’s simply a more stable environment for a tiny sensor filament trying to track glucose changes in real time.
Regulatory Strategy, Not Just Biology
Accuracy differences alone don’t fully explain the restriction. The G7 abdomen data, while slightly worse, would likely still meet the FDA’s minimum performance thresholds for a glucose monitor. The more practical explanation is that Dexcom chose not to submit abdominal data for FDA clearance.
Getting a wear site approved requires submitting a full clinical dataset for that specific location, and each additional site adds time, cost, and complexity to the regulatory process. By filing for the arm only, Dexcom could bring the G7 to market faster with its strongest accuracy numbers. The abdomen data was collected in the same clinical trial but wasn’t part of the formal submission for clearance.
This means the restriction is partly a business and regulatory decision rather than a safety concern. The G7 physically works on the abdomen. It just hasn’t been reviewed and approved for that site by the FDA.
What Happens If You Wear It on Your Abdomen Anyway
Some people do wear the G7 on their abdomen, and online diabetes communities are full of reports from users who say it works fine. Others report more signal loss events, early sensor failures, or readings that don’t match their fingerstick checks.
The clinical data gives context to both experiences. Most abdomen sensors in the trial performed well. But the odds of getting a sensor that doesn’t meet accuracy standards are roughly twice as high on the abdomen compared to the arm. If you rely on your CGM readings for insulin dosing decisions, that difference matters. You’re also using the device outside its approved labeling, which could affect warranty claims if a sensor fails.
If arm placement is genuinely difficult for you due to skin reactions, body composition, or lifestyle factors, the clinical trial data at least shows the abdomen isn’t wildly inaccurate. The error difference is real but moderate. The tradeoff is yours to evaluate.
Comparing G7 Approved Sites to the G6
The shift from the G6 to the G7 removed the abdomen as an option for adults and eliminated the upper buttocks for older children and teens. Here’s how the approved sites compare:
- Dexcom G6: Back of upper arm or abdomen (adults), abdomen or upper buttocks (ages 2 to 17)
- Dexcom G7: Back of upper arm (ages 2+), upper buttocks (ages 2 to 6 only)
- Dexcom G7 15 Day: Back of upper arm only (ages 18+)
If you’re transitioning from the G6 and relied on abdominal placement, the switch to the arm is the biggest practical change you’ll face with the G7. Many users find the arm comfortable after an adjustment period, especially with adhesive patches or bands that help keep the sensor secure during activity. Rotating between your left and right arm every sensor change helps prevent skin irritation from repeated placement in the same spot.