Next-generation CGM with 15-day sensor improves upon previous generation’s accuracy
Key takeaways:
- The 15-day Dexcom G7 had a MARD of 8%, a small improvement over the 8.2% MARD for the currently available G7.
- Of study participants, 91.7% said the device was the same or easier to use than their own CGM.
A 15-day integrated continuous glucose monitor registered accurate glucose values similar to those measured through venous blood samples, according to a presenter.
As Healio previously reported, the Dexcom G7 CGM was cleared in December 2022 for people aged 2 years and older with type 1 and type 2 diabetes. Each sensor for the current-generation device can be used for up to 10 days. Satish K. Garg, MD, professor of medicine and pediatrics at the Barbara Davis Center for Diabetes at University of Colorado Anschutz Medical Campus, discussed a new version of the Dexcom G7, which updates the device’s algorithm and extends the sensor life from 10 days to 15 days.
The 15-day Dexcom G7 is currently being reviewed by the FDA, according to Garg. To provide data to support approval of the device, researchers conducted a prospective study comparing glucose measures from the 15-day Dexcom G7 with blood glucose values determined through a glucose analyzer (Yellow Springs Instrument). Findings from the study were presented at the International Conference on Advanced Technologies & Treatments for Diabetes and simultaneously published in Diabetes Technology & Therapeutics.
“The [mean absolute relative difference] of 8% improves upon the accuracy of the current G7 of 8.2%; demonstrated high accuracy across wear periods, glucose concentrations and rates of glucose change; extended sensor wear with a fast warm-up [time] of 27 minutes, the lowest available in the marketplace; and it is likely with all these features that it might facilitate patient’s behavior and, thus, improve glucose management in people with diabetes,” Garg said during the presentation.
Researchers conducted a multicenter study in which 130 adults with type 1 or type 2 diabetes wore the CGM for the maximum wear time of 15.5 days (mean age, 43 years; 53% women). Participants attended four in-clinic sessions of up to 13 hours in which blood samples were collected every 10 to 15 minutes. Glucose levels from the samples were measured in the glucose analyzer and paired with the CGM glucose values measured in the 5 minutes following the blood sample measure. Glucose manipulations occurred during the clinic visits to assess CGM accuracy in hypoglycemic and hyperglycemic ranges.
CGM accuracy
The mean absolute relative difference (MARD) between the CGM and blood glucose values was 8% for all glucose ranges overall. MARD was 8.3% for glucose values in the normal range of 70 mg/dL to 180 mg/dL, 8.2% for glucose in the hypoglycemic range of 54 mg/dL to 69 mg/dL, 7.8% for the hyperglycemia range of 181 mg/dL to 250 mg/dL and 7.4% for the severe hyperglycemia range of more than 250 mg/dL.
When CGM hyperglycemia alerts were set with a threshold of 240 mg/dL, 95% of alerts were confirmed with a blood glucose value of 240 mg/dL or higher within 15 minutes. When hypoglycemia alerts on the CGM were set at 70 mg/dL, 82% of alerts were determined to be true alerts with a blood glucose measures of less than 70 mg/dL within 15 minutes.
When glucose pairs were plotted on a Parkes error grid, 94.7% fell into zone A and 5.2% fell into zone B, which are the two zones associated with the lowest clinical risk. Garg noted more than 80% of individual sensors assessed in the study had a MARD of less than 10%.
Accuracy was similar regardless of age, sex, diabetes type, baseline HbA1c or BMI.
Sensor durability and safety
Garg said most study participants did not need to replace their sensor during the study, speaking to the durability of the device.
“In this particular study, more than 95% of people were able to [use only one sensor],” Garg said during the presentation. “[There were] only one or two people where the sensor fell off.”
According to the study, there were four device-related adverse events, with two being a local infection, one mild skin irritation and one report of moderate pain or discomfort with wearing the sensor.
In survey data, 98.4% of participants said insertion of the sensor was easy or very easy. At the end of the study, 91.7% reported that the 15-day Dexcom G7 was the same or easier to use than their own CGM.
Reference:
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Garg SK. Performance and accuracy of 15-day G7 continuous glucose monitor. Presented at: International Conference on Advanced Technologies & Treatments for Diabetes; March 19-22, 2025; Amsterdam (hybrid meeting).