***Updated following clarification from the UK Distributor***
Whilst I recently tested and reported back on the Medtrum A6 CGM system, it’s not the only newcomer in the CGM world. Most people have now heard of the of Senseonics Eversense, the implanted CGM that lasts for “up to” 90 days, however, unless you hang around certain groups on Facebook, fewer are likely to have heard of the CT-100, made by POCTech Corporation in China. The UK distributor for this technology is Neon Diagnostics and it’s currently undergoing clinical trials in the UK.
So let’s jump in at the deep end and find out what is the CT-100? On first impressions, it looks very similar to the offerings that both Medtrum and Dexcom provide, and at this stage, pricing isn’t available.
The CT-100 CGMS
Some photos of the components are shown below. Whilst the inserter doesn’t look as consumer friendly as the latest Dexcom device, it doesn’t look quite as scary as the previous generation. The system has been granted a CE mark.
Whilst the User Manual shows the receiver, the website promises an app:
Discussions with the distributor suggest that this is due to be available in Autumn of this year.
The user manual suggests that (unlike many other systems) POCTech is happy to recommend the use of both arms and belly for siting the sensors:
Unlike the Medtrum system, the CT-100 isn’t rechargeable. Instead it has a replaceable CR1620 battery, which are easily available. It claims to be waterproof, but I guess only time spent with the system will determine how long that waterproofing lasts for.
Given that the system requires a battery change every time the sensor is changed (ie Weekly), there is the possibility that it won’t remain waterproof for the entire two year duration that the transmitter is supposed to last. I’m sure that there will be plenty of WeAreNotWaiting testing to see just how long you can go on a single battery though.
The documents all state that the sensors have a life of 7 days, with no mention of restarts, and perhaps more interestingly, they talk about only requiring a single calibration per day. From what we’ve seen with other sensors, I can imagine that you may not need to calibrate it daily with some of the WeAreNotWaiting tools, once they catch up.
They also talk about the sensor assuming a “Unique parallel sensor position” when inserted, which begs the question of how the inserter works, and also that you can adjust the insertion angle. If the sensor is parallel to the skin, then I’m not sure how this second point matters…
In addition, the sensor is apparently unique in that it is composed of 4 electrodes, and assuming that this Chinese patent is linked, these are a working electrode, a reference electrode, a counter electrode and a blank electrode. Digging through the patent, it looks as though the reference electrode is used to reduce noise across the working electrode:
What’s slightly odd is that the sensor is hinged, but once the transmitter is attached, it looks as though the hinge mechanism is locked out. It’s not clear why that is.
Associated Data
Unlike some other vendors, the CT-100 comes with a little more data from trials that they have undertaken (although sadly no source). Whilst I’ll go into that in a moment, there are also ongoing seeding trials with a number UK Diabetes Centres to familiarise Healthcare Professionals and potential users with the system, its function, reliability and accuracy. There are also ongoing Clinical Trials being undertaken by POCTech in three centres in China. I hope this data will be published.
So, first up, some example traces from the CT-100.
As I’ve already mentioned, the company that makes this suggests that it can be used on both arms and the abdomen, and they have provided the following image that suggests there is little difference in the outcomes using either site:
An interesting trace, even if there is little of verifiable information in this. Something we hope proves to be verifiable.
Secondly, the CT-100 Clinical Trial results, from studies done in two medical centres with 73 participants. I understand that these were done in China, and hopefully the data from the ongoing trials will back this up and be published fully.
This data is enormously interesting, because it talks about a MARD (Mean Absolute Relative Difference) versus venous blood that is superior to any other provider out there. In addition, the Clarke distributions are also extremely good. Obviously the trials that are currently underway will provide further insight into these numbers, but at this stage, these are very promising.
The last remaining question is about price, and although I’ve not yet seen a UK price list for this product, the UK distributor is trying to target a subscription model costing £100 per month. This would include a full year’s sensors and the transmitter. At this price, it’s undercutting the Dexcom G6 significantly!
I look forward to trying the system out later in the year, when the phone app becomes available….. Perhaps this is the new competitor that will finally put pressure on the incumbents.
I had the pleasure of trialing this system at the beginning of 2017 and I was impressed. The early version that I tried may have been a little challenging to understand the initial insertion instructions – but I expect these will or could easily be improved and once you know what your doing then its not a problem.
The parallel electrode and the “slightly odd” hinge mechanism: The centre section of the sensor folds up and it’s this section that starts attached to the insertion device (pen looking bit). This guides the electrode/sensor when it is inserted and allows the user to adjust insertion angle. The insertion technique involves taking a pinch of skin/fat and inserting at this angle on the side of the dome you produced by pinching, then after the sensor has been fired in, release pinch and the electrode is meant to be parallel under the skin (perhaps not as precise as the diagram though). The insertion pen then detaches with the two side arms (which can be seen in your first image), and you can then clip flat the hinged section of the sensor ready to slide on the transmitter. For the week that I wore it, it was comfortable, stayed attached and operated without issue. I would be very interested to see comparisons with another system worn on the same user as there were a couple of times when the system was measuring quite a bit lower that blood glucose (i.e. CGM reading between 3-4 mmol/l when blood glucose was 5-6mmol/l), for the rest of the time the accuracy seemed better, and my experience could easily be related to my insertion technique not being perfected, plus its only a sample of 1.
I can’t comment on battery life other than it lasted a week, but I was (at the time of testing) informed that the battery is intended to last for the 7 days and a battery to be supplied with each sensor. We will have to wait and see.
Speaking to Neondiagnostic the intention for costing sounded promising without mentioning actual pricing, but hoping to provide a more affordable route to using CGM in the UK. We can only hope!
Thanks for the review Tom. Might be a bit gorey, but how is the electrode removed? Does it just pull out as normal or did you have to go to the doctor?
not doctor needed, same as Dexcom, Libre or any other based on same technique
This definitely looks like one to watch. I can get 2-3 weeks out of a Dexcom sensor but if the £100 subscription is correct this would still be cheaper. Less money and more accuracy? Yes please!
what does MARD mean? Definition please!
It’s a standard accuracy measure used across all CGM manufacturers. What the letters stand for is in the text, but if you want a detailed definition, it’s worth doing some further research around CGM systems and accuracy measures.