Global CGM device maker, Dexcom, has launched its latest CGM system in Singapore on 1st April 2023. Distributed through its partner DKSH Singapore, Dexcom G6 is marketed as a zero fingerprick, wearable sensor that continuously measures and sends glucose levels wirelessly to a compatible smart device via a transmitter.
The introduction of CGM devices has revolutionalised the management of both Type 1 and Type 2 diabetes with fewer fingerstick tests. Fingerstick tests can only provide us with a snapshot of a patient’s blood glucose at any one point in time. CGM however, monitors our patient’s blood glucose levels 24/7, allowing us to observe a trend and provide a more holistic treatment plan for our patients.
In this article, you’ll find pertinent information on the Dexcom G6, and how it differs from traditional self-monitoring blood glucose (SMBG) devices and other CGM devices like the Abbott FreeStyle Libre.
What is Dexcom G6 and what can I expect from it?
The Dexcom G6 is an FDA-approved CGM system for individuals aged 2 or over. The sensor can be worn on the upper buttocks, abdomen or back of the upper arm.
Dexcom G6 comes with the following components:
- Auto-applicator and sensor: A one-touch applicator is used to insert a slim sensor beneath the skin for continuous blood glucose measurements. Each sensor can be worn for up to 10 days.
- Transmitter: The sensor sends glucose readings wirelessly to a display device through the transmitter. Each transmitter can be used for about 3 months.
- Display device: An Android or Apple-compatible smart device or a touchscreen receiver which displays real-time glucose data.
What is the difference between CGM and SMBG?
SMBG works by having patients perform a number of glucose tests each day or each week. The test most commonly involves pricking a finger with a lancet device to obtain a small blood sample for determination of blood glucose level. Patients can then use their SMBG results to correct any deviations out of a desired target range by changing their carbohydrate intake, exercising, or using more or less insulin.
CGM (rtCGm or isCGM) on the other hand, does not require any fingerpricks. Patients will instead apply a wearable sensor at the approved location, and the sensor will be able to record their glucose levels continuously. This information can then be transmitted wirelessly to your smart device for recording and interpretation purposes.
What is the difference between rtCGM (Dexcom G6) and isCGM (Freestyle Libre)?
rtCGM refers to real-time continuous glucose monitoring (Dexcom G6) while isCGM refers to intermittently scanned CGM (Freestyle Libre). While both devices allow for zero fingerprick glucose monitoring, there are some main differences between the two:
Fingerstick Calibration
While Dexcom G6 allows for personalised user calibration, the Freestyle Libre is factory-calibrated and user calibration is not allowed.
Accuracy
Looking at the mean absolute relative difference (MARD), which is an indication of accuracy in CGM values, Dexcom G6 performs better than the Freestyle Libre with 9.0% for abdominal wear compared to 9.2% for the Freestyle Libre.
Most CGM systems have good accuracy for the glucose range between 7.8 to 16.7 mmol/L. The range that differentiates the CGMs is the hypoglycaemic range. Data shows that Dexcom G6 is more accurate in the hypoglycaemic range compared to the Freestyle Libre, with 88.5% achieving ±15% point accuracy compared to 52.8% for the Freestyle Libre. Such inaccuracy in the hypoglycaemic range directly translates to important treatment decisions – whether or not the patient is truly hypoglycaemic and should receive hypoglycaemia treatment.
Population
Dexcom G6 is approved for ≥ 2 years of age, while the Freestyle Libre is approved for ≥ 4 years of age. This means that Dexcom G6 can be used in a larger population of pediatric type-1 diabetic patients.
Location of Wear
While the Freestyle Libre sensor is only approved to be worn on the upper arm, the Dexcom G6 sensor is approved to be worn on the abdomen and upper arm (≥ 2 years of age) and the abdomen and upper buttocks (children between 2-17 years old). This may be preferred in countries with a tropical climate like Singapore as users may choose to wear their sensors at more discreet locations of the body.
Wear Length
Dexcom G6 has a shorter sensor life of 10 days compared to 14 days for the Freestyle Libre.
Warm Up Time
Dexcom G6 takes 2 hours to warm up. Freestyle Libre 1 takes 2 hours to warm up as well, but Freestyle Libre 2 takes only 1 hour to warm up. This is an important feature because glucose readings are not available for the duration of the warm-up period.
Threshold-based vs Predictive Alarms
The Freestyle Libre does not provide any alarm system to notify patients of glucose levels that are too high or too low. While the Freestyle Libre 2 has a threshold-based alarm system, users will not be able to prevent incidents such as hypoglycaemia or hyperglycaemia. This is unlike Dexcom G6, which has a predictive alarm system that can help prevent out-of-range blood glucose levels.
Data Delivery
Users of Freestyle Libre must scan their sensors to see their glucose levels. This may lead to inaccuracy in treatment if users fail to comply with scanning requirements. The international consensus recommends users to scan every 8 hours to avoid gaps in data collection. Conversely, the Dexcom G6 provides real-time glucose readings every 5 minutes, eliminating the need for users to physically scan their sensor.
Efficacy
Based on two landmark trials – ALERTT1 and iHART, rtCGM resulted in a clinically significant improvement in time in range (TIR) and reduction in time below range (TBR) compared to isCGM. These effects were observed to be sustained and would be reflected as improved HbA1c levels as well.
Summary Table of Differences
| Dexcom G6 | FreeStyle Libre | |
| Frequency of readings | Automatic readings every 5 minutes | User must scan the sensor with their phones with the FreeStyle Libre app open to get a glucose reading |
| Area of application | Upper arm, abdomen and buttocks | Back of upper arm |
| Approved ages | ≥ 2 years old | ≥ 4 years old |
| Sensor wear time | 10 days | 14 days |
| Warmup time | 2 hours | 1 hour |
| Alerts and alarms | Customizable alerts and alarms, including the mandatory “urgent low” and “urgent low soon” alerts. Predictive alert 20 minutes before patient goes into hypoglycaemia | None for Libre 1
Threshold-based alarm for Libre 2 |
| Accuracy (MARD) | 9.0% | 9.2% |
| Interoperability with insulin pumps | Yes | No for Libre 1
Yes for Libre 2 |
References:
- Lameijer A et al. Diabetes Res Clin Pract. 2021 Jul;177:108897. doi:10.1016/j.diabres.2021.108897.Epub 2021 Jun 5.
- Battelino et al. Lancet Diabetes Endocrinol 2022. https://doi.org/10.1016/S2213-8587(22)00319-9.
- Puhr S et al. Diabetes Technol Ther. 2019;21(4):155-158. 2. Acciaroli G et al. J Diabetes Sci Technol. 2021; DOI:10.1177/I932296820982584.
- Visser et al. Lancet Diabetes Endocrinol 2023; 11: 96–108
- Reddy M et al Diabet Med. 2018 Apr;35(4):483-490
