Dear Adamrit, DMM49 et al,
I used a Medtronic 640G and a hacked Bluetooth Libre 2 with Xdrip for several years and then moved onto a Tandem Tslim X2 with Dexcom G6 in February 2023. I understand your confusion and difficult making a choice. The manufacturers don’t make it easy do they? It’s interesting isn’t it how the manufacturers obfuscate to make clear easy, comparison challenging? Sadly, our NHS Diabetes Teams also struggle to advise too because of the wide variety of pumps available and difficulty comparing various pump pros and cons. I feel a good analogy is it is like trying to advise the differences between different mobile phone models and manufacturers… the rate of change means a constant need to keep up-to-date. To be fair, NHS staff are hugely over-subscribed and over-worked so it is entirely understandable they can struggle to keep up with patients like us who have a vested interest in keeping up-to-date and everything we can as soon as it comes out
Anyhow, after one year of research and waiting around to see if the Tandem Tsport (now called Mobi), the pump I actually wanted, would come out in the original timescales promised Xmas 2021/Jan 2022 I was forced to make a choice 3 years out of warranty (thanks Pandemic). So, I went for the Tandem X2 with Control IQ. To make this choice I used a table from an academic paper from late 2021 that compared the, (at the time), main available insulin pumps, sensors, etc. I even updated costs, etc, directly onto the table. Please see pages 5 to 7.
What I found most interesting and helpful was seeing a comparison made side-to-side with all the main comparable elements put in a clear table format with corrections made for the various statistical elements to ensure a useful comparison. This included, types of compatible sensors and their duration and accuracy, insulin compatibility, algorithm used, waterproofing, boost/exercise modes, warranty, power source, advantages and disadvantages, and perhaps most useful, the ‘(%) Time in Range (3.9 to10mM) achieved in pivotal trials’.
As you can see this element shows there is very little, Time in range (TIR) percentage-wise, differentiating between the pump models, with the CamAPS/Dana RS (TIR 76%) having the best results followed, by Medtronic 780G (TIR 75%) and the Tandem X2/Dexcom G6 (TIR 71%), etc.
The difference in blood sugar control impact between these pump/sensor systems was therefore only 1 to 5%...
In my opinion therefore, the key point in making your choice should not really be the type of hybrid loop system, but other factors such as ease of use, consumables supply, level of input required, particular system strengths and weaknesses, and vitally, how they would impact upon you as an individual. The reported 5% difference in TIR impact would certainly be improved more by your engagement. In other words, if you are really on top of your diabetes then it is likely the academic paper’s TIR 5% difference is negligible and what therefore counts is the other pump/ sensor factors and how they engage and impact upon you.
In my case, very simplified, the Dana RS and CamAPS system was rejected due to the Dana RS pump looking to an ‘old fashioned’ design and the CamAPS being a mobile phone and key ‘subscription’ based app. Yes, CamAPS would overall give a better result by a few percentiles but this would involved a more complicated set and start up, an older looking design pump and a subscription… what if I go abroad, how would this subscription be affected? What would happen to the hybrid closed loop system if I lose my phone?
The X2 on the other hand has its issues (signal loss due to screen facing antenna/ clunky reservoir change), but it looks and feels modern, is slim and unobtrusive, and importantly has it’s algorithm built into the Control IQ software onboard so no problem if you lose your phone. There is also the possibility of software updates and fingers crossed the Dexcom G7, Libre 3 and mobile phone bolusing are all coming as updates in the next two quarters.
The main issue with the Tandem X2 is it’s reliance on the Dexcom G6 which really is a huge step back from the Libre 2. The G6 is larger, more complex to insert and start and only lasts 10 days versus the Libre 2’s slim profile and 14 day lifespan. This should be fixed with the coming software upgrade.
The Medtronic 780G was rejected quickly due to the Guardian Sensor only having, at that time, only a 7 day application and needing calibration.
Now, as mentioned, the 2021 paper and its table are out of date due to Ypsomed, Omnipod, and several other new systems coming onto the market. However, I feel if you print out the table add a few extra columns you could add in their factors and it would help you make a comparison and thus decision.
So in summary, yes, it did take a little fiddling around getting used to Tandem’s system and eccentricities but after a week it was really as easy as the 640G. The X2 does have its issues… e.g., signal loss due to the antenna only facing out from the screen (face down in bed or your pocket results in signal loss), the fiddly reservoir with silly plastic connector that gets in the way of belts, etc, and the Dexcom G6, which is large and in two pieces and a faff to use. However, you get used to them and find work arounds quickly. Charging the battery really isn’t a problem as it charges lighting fast and I often do it while using my laptop or even carry a power bank. I’ve even discovered you can, carefully and disconnected, refill an old reservoir directly while still connected to the pump if you forget a new reservoir. Control IQ (CIQ) is good, not perfect, but good. Like all the Hybrid closed-loops it is not really a closed loop system at all, but rather a blood sugar assistant that makes some boluses for you to try and prefent a hyper, and can stop insulin which might stop a hypo. You as the user still have to do a lot of thinking, bolusing and checking. No where near as much as before but it’s not the holy grail of a fully automatic closed loop system. I feel the wording ‘hybrid’ close loop is actually misleading. Finally, I often leave my CIQ on sleep mode because it keeps my blood glucose target between 6 and 6.5. rather than daily standard 6 to 6.7. The X2 does not allow you to set your own blood glucose targets. This is another disadvantage as the Dana RS/CampAPS allows you to set your blood glucose level target. However, this comes at the price of more user input so swings and round-a-bouts…
I hope this helps in some small way
