First Type 2 Diabetes Publication Comparing Pros and Cons of Two Preclinical Continuous Glucose Monitoring Systems
We recently reviewed a publication reporting on an optimized preclinical continuous glucose monitoring system, and the advantages this could bring over conventional blood glucose measurement. In the publication, Wang et al successfully showed the utility of the HD-XG glucose sensor in primate models.
In a follow up article, featured in this month’s Nature Scientific Reports, the authors compare two continuous glucose monitoring systems in conscious and moving-free non-human primates (NHPs, Macaca fascicularis) for the first time.
Dexcom G4® Platinum vs HD-XG Telemetry Device and Glucometer Evaluated in Normoglycemic and Diabetic NHPs
The new publication highlights in a head to head comparison the advantages and some characteristics of using the Dexcom G4® Platinum, an FDA-approved device for patient use, and HD-XG transmitter system to monitor body glucose continuously in conscious, stress-free NHPs.
The team used both normoglycemic and diabetic NHPs - implanting the Dexcom G4 Platinum subcutaneously or the HD-XG glucose sensor arterially for glucose monitoring. The overall take home message is that both devices showed significant correlation between glucose levels measured in traditional glucometer tests.
Both Systems Show a Range of Benefits Over Conventional Glucose Monitoring
Both of the implantable systems have a range of benefits over standard glucose monitoring:
- 24-hr consecutive monitoring of glucose changes
- stress-free glucose monitoring
- no anesthesia required during GTT
- less labor intensive GTT
- instant glucose readings without blood collection and assay.
Tissue vs Arterial Readings Show Differences Following ivGTT
During administration of an oral glucose tolerance test (oGTT) both the Dexcom G4 Platinum and HD-XG transmitter showed very similar glucose readings to glucometer readings.
In contrast, following administration of an ivGTT, compared to HD-XG transmitter or glucometer, the Dexcom G4 Platinum detected a delayed (10 minute) decreased glucose peak.
This is all due to the subcutaneous placement of the sensor, with the Dexcom G4 Platinum reading interstitial glucose which trails far behind blood glucose change, while the HD-XG reads arterial blood.
Dexcom 4 Platinum is the Quicker, Easier, and Less Expensive Option
Compared with the HD-XG arterial system, the Dexcom 4 Platinum with subcutaneous placement is easier to install and less invasive, less expensive, and provides an acceptable safety profile.
The disadvantages include the moderately delayed glucose readings following sudden glucose changes (as discussed above), which will likely worsen over implantation time as encapsulation develops. Interstitial glucose readings can also vary due to local fluctuations in subcutaneous blood flow.
Sensor lifetime is also quite short due to an inflammatory response resulting in biofouling and encapsulation, and fixing the sensor stably in active animals can be challenging.
HD-XG Telemetry Method More Stable but Price/Resources can Limit Sample Size
While the HD-XG telemetry probe is fixed arterially, which may provide a more stable option, it also means a more invasive option, though it is a longer lasting sensor with more frequent sampling.
As the device is only currently used for preclinical research, it is also more expensive than the Dexcom 4 Platinum. As spontaneously diabetic NHPs are a limited resource, and the HD-XG is an expensive asset, the sample size used for the diabetic HD-XG group was small for this study. While this was a qualitative study which presented individual data, further larger studies which may want to perform statistical analysis may find this limiting.
Innovative Stress-Free oGTT Method Also Presented with Continuous Glucose Recordings
On top of the device comparison, the paper also introduced a novel way to perform a stress-free oGTT with continuous glucose recording. Oral or nasal gavage is a typical way for glucose administration if an oGTT is performed in lab animals, including NHPs.
Self-administration of a banana-glucose meal for oGTT in NHPs seemed to significantly reduce the stress levels inferred from baseline glucose levels. The baseline glucose level was approximately 20mg/dL lower in the banana-glucose feeding animals than in those oral glucose gavage group.
Continuous Glucose Monitoring Provides a Practical and Stress Free Approach
This publication shows that remote and continuous glucose monitoring via implanted Dexcom G4 Platinum or HD-XG telemetry device in conscious, stress-free, and moving-free monkeys is highly feasible.
Each device has its own pros and cons for preclinical research, but both provide a sophisticated approach to investigate continuous glucose changes during therapeutic preclinical investigations.
Further reading on the utility of the HD-XG glucose sensor in primate models: Wang et al. Long-term blood glucose monitoring with implanted telemetry device in conscious and stress-free cynomolgus monkeys. J Endocrinol Invest 2017;40(9): 967-977.
Read our blog post reviewing the paper: Recent Type 2 Diabetes Publication Demonstrates Preclinical Study Benefits of Continuous Glucose Monitoring