What Is a Dexcom Sensor?

Dexcom sensors are part of a wearable CGM system that tracks glucose levels continuously through the interstitial fluid just beneath the skin. Rather than relying on isolated blood sugar readings from fingerstick tests, Dexcom CGM systems send glucose readings to a receiver or smartphone approximately every five minutes. The latest version, Dexcom G7, features a smaller design, quicker warm-up time, and enhanced software integration compared to earlier generations.

Once placed on the upper arm or abdomen, the sensor measures glucose levels and transmits the data wirelessly. This ongoing stream of information allows users and their healthcare providers to detect patterns, anticipate glucose highs or lows, and adjust treatment proactively.

How Accurate Are Dexcom Sensors?

Research has repeatedly confirmed the accuracy of Dexcom sensors, particularly the G7 model. In a pivotal multicenter study involving over 300 adults with type 1 and type 2 diabetes, the Dexcom G7 achieved a Mean Absolute Relative Difference (MARD) of 8.2% when worn on the arm and 9.1% when worn on the abdomen. Over 95% of glucose readings were within 20% of laboratory reference values. These results exceeded the established standards for CGM performance and demonstrated strong reliability across multiple days of wear, including during rapid glucose changes.

Similar findings have been observed in special populations. For example, a study conducted in pregnant women with diabetes showed that 92.5% of CGM values were within 20% of reference values across a range of glucose concentrations. In patients undergoing hemodialysis, the G7 maintained a MARD of 10.4%, while still meeting error grid safety criteria.

Even in complex clinical settings such as the intensive care unit (ICU), where factors like fluctuating hemodynamics can interfere with CGM performance, the Dexcom G7 showed comparable accuracy to non-ICU hospital patients. While the MARD was slightly elevated in this environment, the device still provided consistent glucose trend data that may prove useful for future inpatient insulin management strategies.

Safety of Dexcom Sensors

The safety profile of Dexcom sensors has been established across diverse clinical trials and real-world studies. No serious adverse events related to the device were reported in the major studies evaluating the G7 model, including those involving pregnant women, children, or dialysis patients. Mild site irritation was occasionally noted, but these reactions were typically self-limiting and did not interfere with sensor function.

The 10-day wear period of the Dexcom G7 was completed successfully in over 90% of cases in clinical trials. This durability reduces the need for frequent sensor replacements and contributes to a more stable user experience. The device does not require routine fingerstick calibration, further minimizing the physical burden for users.

Clinical Impact on Diabetes Outcomes

Dexcom sensors offer more than just convenience. Several studies have shown that their use leads to measurable improvements in glycemic control and quality of life. In adults with type 2 diabetes using insulin, real-world data indicated an average A1C reduction of 1.6 percentage points and significant weight loss, without an increase in hypoglycemic events. These changes were statistically and clinically significant, suggesting that CGM use may support behavioral changes and improved self-management.

In the Veterans Health Administration, a large cohort study comparing CGM users to traditional blood glucose monitoring found that CGM users had a greater decline in A1C over 12 months and experienced fewer emergency room visits for hypoglycemia. The findings were statistically significant even after accounting for demographic and clinical differences between the groups. This suggests that continuous monitoring may reduce not only long-term complications but also acute medical crises.

In inpatient care, a randomized clinical trial found that CGM-guided insulin dosing significantly reduced the recurrence of hypoglycemia compared to standard point-of-care testing. Patients in the CGM group spent less time in dangerously low glucose ranges and experienced fewer repeat episodes. These results support the safe use of CGM in hospital settings, especially for high-risk individuals.

Evolving Use Cases and Practical Considerations

Although originally designed for outpatient use, Dexcom sensors are now being studied in an expanding range of scenarios. In pediatrics, for instance, CGMs have been integrated into hospital workflows with good accuracy and strong clinical agreement when compared with laboratory glucose readings. This paves the way for safer, more responsive diabetes care for children in inpatient settings.

Certain environments still present challenges. During moderate-intensity aerobic exercise, older Dexcom models like the G4 showed reduced accuracy due to rapid glucose shifts. Although newer models like the G7 have addressed many of these issues, users are still advised to interpret CGM data cautiously during periods of intense physical activity. Similarly, research into CGM use during scuba diving found that current sensors, including the G7, do not yet meet accuracy thresholds for safe non-adjunctive use underwater. Capillary blood glucose testing remains essential in these extreme scenarios.

The Future of Glucose Monitoring

Dexcom sensors are at the forefront of a broader shift in diabetes management, where real-time data empowers individuals to make better, more informed decisions about their health. The G7, with its improved accuracy, convenience, and safety, is supported by a growing body of statistically significant research across multiple populations and clinical contexts. As more studies validate its use in hospitals, pediatrics, and other special populations, the Dexcom sensor is positioned to become a cornerstone of personalized diabetes care.