Hype or Hope? Dexcom, Tandem tSlim review and 2020 round-up

Wait... hang on... December 31st? That can't be right! Have we actually had a year this year? And how come any of the things that happened this year seem to have happened at least 18 months ago? No time has passed. But it has passed at a snail's pace. And at the same time we've all become accustomed to living completely different lives.

Doing a sort of round-up post for the year that never happened doesn't seem worthwhile. There are only so many times I can talk about avoiding a Zoom-based diabetes thing before I'm going to run out of waffle. Yes even me.

tldr; 2020 was a bit pants. But I really like the tSlim and Dex.

Tandem tSlim with Dexcom G6

Out with the old
I've been meaning to write a post or three about my experiences of the Dexcom G6 and my switch to the Tandem tSlim:x2 (and subsequent upgrade from Basal IQ to Control IQ) since the Summer, but for all sorts of reasons that series of posts never arrived. I have lots of pics of pump and graph cluttering up my phone that were apparently going to eloquently show something or other, but it's all so long ago now that I can't really remember what it was I was going to say.

I am self-funding Dexcom G6 sensors, and it was the first time I had used Dexcom. Such is the relentlessness of the positivity around Dex, that I think secretly I might have been hoping that I wouldn't find it all that special. 

I sprung for the 'starter pack' which gives an official 30-day's worth of coverage before I committed to going for the tSlim, so that if my body chemistry didn't get on with the Dex I could opt for Medtronic's MM670G (or similar) with self-funded Guardian G3 sensors. I had always got on well with Enlites and to some extent G3s too, and I was pretty sure that I would have got on well with the MM670G if that was what I'd gone for.

Inserting the Dexcom sensors was really straightforward, and initially I ran the sensors with my iPhone (not yet having taken the plunge on the pump). They restarted easily, and I didn't even have to faff about with unpeeling tapes and removing the transmitter thanks to these instructions. What really struck me though, was how well the factory calibrated G6 tracked fingerstick results from my Contour Next Link 2.4 meter (still my go-to BG meter). The first few days were uncanny. Spooky even. It didn't appear to be hype at all - generally Dexcom was reading only a few decimal points away from any fingerstick I took.

Even a Dexcom G6 lags a little now and then

Reassuringly though, I did see a characteristic post-hypo-sensor-lag on about the 3rd day, where the Dex stubbornly continued bleating about low BG for 5-10 minutes after I was back above 4. So it was a regular CGM and not witchcraft after all. It was just that it was a really good CGM for me.

Joking aside, those early excellent matched pairs (against fingerstick checks) really helped me trust it as a new bit of kit though. 

And even better, while the factory calibration is excellent for me, and I've all but given up cross-checking with fingersticks, if I *need* to recalibrate the Dexcom G6 because it has drifted a little... I can! 

After a few weeks with the Dexcom I was confident to put in my request to switch to the Tandem tSlim when the warranty ran out on Threepio.

Switching to the Tandem tSlim:x2

I affectionately called my first insulin pump robot counterpart 'Artoo' (R2P2 - replacement to my pancreas #2), and kept with the Star Wars theme with my MM640G as 'Threepio'.  This bit of kit promised to be wiser and much more autonymous though, so I've taken to calling it HAL (hybrid automated loop), though of course it would be much funnier if a certain tangerine diabetic had made that joke, [affects creepily calm synthetic robot voice] "What are you doing Dave? I'm afraid I can't let you eat that biscuit..." etc.

Staying in its box until I was trained up.

As all this was happening while the healthcare system was in some degree of chaos, and all those buzzwords like 'social distancing' were in full flow I wasn't sure how any kind of switchover was going to be able to happen - but in the end, in classic 2020 style I did my pump training via a video call having had the box of goodies delivered direct to my house.

I had a few weeks with Basal IQ before switching to the smarter Control IQ. Both worked well for me, and each have their own idiosyncracies. I have tried to do as little fiddling as possible, taking an initial 7 days to see how each got on when left to their own devices to try to learn what they are good at, and where they struggle. Also learning how to give them the right information to get the best results.

For those outside the Tandem bubble (seriously 2020? another word you've mangled?!), Basal IQ is Tandem's 'predictive low glucose suspend' algorithm, which stops basal insulin in order to try to reduce risk of hypos. Basal IQ is a little more responsive I feel than Smartguard on my MM640G. In that it can turn on and off more quickly, and doesn't have a minumim duration or enforced gap after it has completed. There was a major irritation for me when running the Basal IQ algorithm in that the tSlim moaned at you if you set a 0% TBR, though ot was more than happy to set one itself. Indeed, the tSlim got very grumpy if a TBR was set that was less than 50% of your lowest basal rate. A degree of warbling which was as unwanted as it was unnecessary.

This irritation was short lived though, as I soon upgraded to Control IQ. One of the nice things about the tSlim is that you can plug it into a computer and upgrade the software on the pump. Which means that if they release fancier, smarter, or even just mildly less irritating versions of the pump software, then you don't have to wait until 4 years have passed to take advantage. All I need now is to find the email address of the person to send my Helpful Suggestions to, for inclusion in the next release 😉

Conclusions

I guess I've been on the tSlim a little short of 6 months now, and I can honestly say that I am really glad I made the switch. I loved the MM640G, but the clunkiness of the Medtronic chassis, and some of the million-presses-UX-interface-tedium was wearing me down. Plus the newer G3 sensors were a bit more flaky and prone to overnight calibration requests for me. There are things about the tSlim I would hope would improve - not least the reservoir filling, which is every bit as fiddly as people say. Their reservoirs really need re-engineering so that the 'white dot' behaves more reliably (tSlim users will know what I mean). 

And what of results? Well I've not really that the nerd-energy for much actual data comparison, but going on gut feeling I would estimate that the tSlim has bumped my TIR (time spent between 4.0 and 9mmol/L) by somewhere between 5% and 15%. What used to be a really good week of results is rapidly becoming pretty normal. Control IQ still needs watching as it often responds a little later than I need, and it's not perhaps as 'hands off' as I was hoping it might be, but Control IQ really nails the little adjustments for me. It struggles with circumstances which are a bit wobblier, but it seems very good at optimising gentle drifts. Overnight with Sleep Mode has been spectacularly good. Almost no alarms, and almost always waking in the 5s to 7s.

Gotta be happy with 28/30 days above 80% TIR

It will be really interesting to see if this has had any kind of effect on my HbA1c, but to be honest, I increasingly find A1c a poor proxy for how I feel my diabetes management is going from month to month. It may still be seen as an important stat as far as research goes, but I'd far rather focus on the ebb, flow, and varying proportions of BG values that lie behind it. But that's another post I'll probably never get around to writing...

Here's hoping for a peaceful, healthy, happy and significantly more stable 2021 for us all.

Guest Post: From Dx to X2 (Tandem T:Slim) by Robert S

This is a guest post by Robert S who dropped me a line via FaceTwit as he had been  writing down his 'diabetes story' but didn't have a blog to share it on. Apparently he has been good enough (or mad enough?) to read my ramblings in the past and offered it as a guest post for sharing here. His story echoes much of my own, and I am very interested to read that he has chosen the Tandem T:slim X2 insulin pump out of the current offerings, as that is one I have quietly got my eye on too. Here is Robert's story. Enjoy!

Tandem T:slim X2

My Diabetes Story, by Robert S

I was diagnosed in 1994 at the age of 38, about 10 years after my older sister who had (eventually) been diagnosed at a similar age. I was given a number of very vague, unhelpful leaflets & sent on my way.

I spent the next few years religiously taking insulin as instructed but with pretty poor results.

Diabetes clinics were a trial for me, with many 'must do betters' but precious little advice on how to achieve this. Several times I was mistaken for type 2 & had some very odd conversations. I probably presented as typical type 2, middle aged and overweight, and most people at the clinic were type 2. However they clearly hadn't read my notes which didn't inspire confidence.

I was divorced during this period so I was very much dealing with it on my own.

The internet arrived & eventually I discovered diabetes forums. Wow, what a revelation! There were other people having the same problems as me. A LOT of people! Bad news for them but a great relief that it wasn't just me.

Importantly some of these people were working to improve their diabetes & describing how.

At the time of my diagnosis carbohydrate 'exchanges' seemed to be going out of favour but for me, at least, carb counting was a very vague concept.

The forums prompted me to do the online carb counting course set up by Bournemouth Diabetes & Endocrinology Centre (BDEC). It didn't solve all my problems but for the first time I felt I had a method for moving forward.

By this time I had moved from 'Humulin I' & 'Humulin S' to a basal/bolus regime, which also helped.

My GP surgery contacted me suggesting that they monitor my diabetes now they had a Diabetes Nurse. Being rather disillusioned by my experiences in the clinic system I accepted.

I enjoy programming & wrote software for my phone to record everything & do some basic dosage computations. My HbA1c had never been really terrible, usually in the low 8s (8% or 64mmol/mol, Ed), but I honestly don't know how. Some hard work got it down to the mid 7s (7.5% or 59mmol/mol, Ed).

So the situation had improved somewhat & I felt more in control.

Sadly, another event encouraged my efforts, as my sister died from diabetic complications at the age of 64.

From the beginning hypos were an almost daily event. The worst being overnight. I've always had good hypo warnings, but at night hypos tend to progress further & I would wake up soaked in sweat.

By 2013 though, the overnight hypos seemed to be worse. I discussed it with the diabetes nurse at my GP practice but the best advice was always eat some supper & don't go to bed below 8mmol/L. I was already doing this.

I'd read about Continuous Glucose Monitors (CGMs) which looked very interesting, but were way too expensive for me and, I noted, you still needed to do finger sticks.

Things came to a head on Boxing Day night 2013. I was away staying (alone) in a hotel & I woke up with a hypo around 1:30. Dragged myself out of bed managed to force a some glucose tablets & a biscuit down me & fell asleep. The next thing I knew I was waking curled up in a ball under the duvet, sweating yet shivering to the point where my teeth were chattering continuously. The worst thing was that I couldn't move to do anything about it. Eventually I fell asleep wondering if I'd wake up.

I decided to self fund a Dexcom G4, at least for a while. By the end of January 2014 I was wearing my first CGM. I watched it obsessively. On the second day I attended a graduation ceremony and was offered a glass of Bucks Fizz & a blueberry muffin. I thought I was being sensible & only ate about a third of the muffin & bolused for it. The effect on my blood sugars was fascinating. I watched as the graph went up, & up & up. I don't remember how high but it was an eye opener.

Initially it was more about the alarms which warned me in time to stop low blood sugars. Still annoying at night but I no longer woke up sweating.

I began to learn from the readings. The first big thing I noticed was a fairly consistent dip in my blood sugars around 1:30 to 2:30 in the morning. This made it difficult get my overnight average to a sensible level & went some way to explaining the nocturnal hypos. I tried varying the time that I was injecting my basal (Lantus) moving it from evening to morning, or splitting the dose. Nothing was really satisfactory.

Someone in the DOC (Diabetes Online Community) suggested changing my basal insulin. After chatting to my GP I moved to Levemir. I had a lot of trouble sorting out the dose, being quite worried that I had to take so much more than I had of Lantus. It was a split dosage & gradual adjustments left morning/evening doses very different, but, it was working. I saw some fairly horizontal overnight graphs, something I'd never ever seen before.

This encouraged me & I also made other adjustments; splitting boluses for some meals, not being afraid to do corrections between meals & so on.

Nothing was perfect but I did feel more 'in control'. Things still went wrong but when they did I was confident I could put it right. My HbA1c went below 7% (53mmol/mol) for the first time.

Using online instructions I built a box of electronics which allowed my Dexcom sensor data to be transmitted to my mobile phone. Thanks to #WeAreNotWaiting I set up a NightScout website to display my data.

This was all great, but hard work. I was doing a lot of injections, up to 12 a day. Also absorption of my basal injections was rather erratic, sometimes as I would expect, sometimes not. The best location was my thigh, but despite rotating sites there were problems.

By this time I'd been reading about hybrid closed loop (artificial pancreas) systems. First the DIY systems OpenAPS, Loop, and AndroidAPS, then the first commercial system the Medtronic 670G. This was exciting stuff but it was clear that first you needed to have an insulin pump. I had in fact been offered one about 15 years before but was then horrified at the thought of being permanently connected to the thing.

I decided I would now like to try one. It was not something my GP surgery could sort out so I had to be referred back to the hospital. This proved to be a long process, several months. I still don't know why. Eventually it went through just before Christmas.

By the time I met up with the DSN at the hospital a month or so later I had all but convinced myself I was wasting my time as control was simply too good?

Sure enough the DSN was impressed with my readings but it didn't help my case. I pointed out that I was doing a lot of injections each day. Not relevant.

"How many hypos do you have?"
"Hardly any."
"Yes, but that's with the Dexcom you are funding?" This wonderful lady was on my side & looking to find a way.
"Lots, nasty ones, that's why I bought it"
"That's it! Now let's have a look at the pumps you could have."

What! Really! To be honest I would have accepted some dusty old pump from the back of a drawer..

But when I focused on what she was saying I could barely believe my ears. I'd done a lot of homework on pumps & she was mentioning the Medtronic MM640G & the most advanced, the 'Artificial Pancreas' MM670G.

Then she added the Tandem T:slim X2 to the list. Again I'd read about it but thought it was only available in the USA. Positively it would soon be linked to the Dexcom G6 I was already using. I love my G6 & it seems to compare favourably with the Medtronic sensors. (Not that I had any personal experience of them).

Uniquely the software (firmware) of the X2 can be updated & in the UK will soon include Basal-IQ, a system which automatically suspends insulin if it thinks you will go low. There is also the promise of a full hybrid closed loop option similar to the Medtronic 670G - again an over the internet update.

I made my decision; the T:slim X2. By mid March after a couple of training sessions, I walked out of the hospital attached to my pump. Very exciting & not a little nerve racking!

We had agreed a 30% reduction in the basal dosage compared to my Levemir. A profile was set up.

During the evening it became clear to me that this was still too much & changed to an 80% temporary basal rate (TBR).

My Dexcom woke me about 1:30. I dropped the temporary basal to 75% and had a small snack. Readings got 'stuck' in the low 4s & eventually I ate again and reduced to a 60% TBR.

So not much sleep but at least I was closer to the required dosage. One thing that I kept thinking that night was "How does anyone do this without a CGM??" Presumably they start with a much more conservative dosage.

I had worried about what to do with the pump at night, and it was a problem. Clipping it on my waistband sort of worked but it would slide along to an uncomfortable place or slip off completely. I now have a 'Spibelt' with a pocket for the pump which is much better.

A week in now & I'm doing remarkably well, some days over 90% of my readings have been 'in range' - between 3.9 & 9.9mmol/L. I know this is probably just a 'honeymoon period', having had type 1 for over 20 years I find I'm waiting for reality to reassert itself & everything to go wrong...

The pump itself is a very neat device. It is small & has a nice clear touch screen. If you are used to smartphones then it is easy to use. It seems well made, time will tell.

I've had some practice with temporary basal rates as mentioned but I've also been playing with 'Extended Boluses' a new concept to me, promising, but I need to experiment.

As with all pumps the big advantage is the same as the big disadvantage - namely that it is always connected to you. It's great that I don't have to remember my pens & I won't miss those injections - I stopped counting at about 50,000 several years ago.

A big advantage is that you have a record of every dose. No longer do I have to wonder 'Did I do that or not?'

There's also the precision of boluses & the in built Bolus Wizard (Calculator). I am learning to trust the IOB (Insulin On Board) figure on the pump. Previously I had tended to intervene too soon when blood sugars rose quickly.

I'm told that changing infusion sets on the X2 is slow, but it seems OK to me having never used anything else.

I'm looking forward to improving my settings & the upgrades mentioned above.

For the first time in my diabetic life I feel as though I am 'ahead of the game', and yes, I know I am lucky.

Diabetes has never been so interesting!

By Robert S.