Hi ho! Hi ho! It’s back to Medtronic I go

Medtronic MM780G and Simplera Sensors
(Apple watch not included)

Hello. It’s been a while!

The embryonic posts I had in my mind about living with the Tandem tSlim never seemed to manage to make it to the top of the ‘to do’ pile, and remain unwritten - which I'm sure was a relief all round. But there’s nothing quite like a deadline to spur a (largely ex-) graphic designer into action. And tomorrow I am awaiting the delivery of my new insulin pump, as the warranty on my Tandem tSlim has elapsed. So it felt like a long overdue blog post could no longer be avoided.

Interestingly the ‘new’ pump isn’t particularly new at all. It’s the pump I rejected in favour of the tSlim 4 years ago. This might surprise some people. So why am I not sticking with the tSlim? Or joining the ever-growing horde of podders? But no, for me it’s the venerable MM780G, but with the fancy new Simplera sensors.

So Long tSlim

Confusion about my choice of ‘new’ (old) pump might be even more confusing because I have repeatedly said that I’ve never had better results than with the tSlim. My overnight readings in particular have been spectacularly good, very stable, and never required the alarm/calibration acrobatics that plagued my last days with my MM640G. Automated night mode suited me brilliantly, and I just expect to wake between 5.5-6.5mmol/L every day.

Non-shabby 90 Day Results

Control IQ added approximately 10-15% to my average ‘time in range’ which I choose to set 3.9-9.0mmol/L. My previous general 70-80% has become more like 80-95% most days. This is pretty spectacular with something as fickle, contrary, and annoying as Type 1 Diabetes.

Dexcom G6 mostly tracks my BG levels brilliantly. While I was self-funding (for approx 3 out of my 4 tSlim years) I was able to stretch most sensors to run for 20 days with a viable and solid flow of data, that I was confident to use for most corrections, alerts, and bolus calculations.

So in many ways, I am really happy with the system, and have certainly seen significant improvements from running a hybrid closed loop system. I’d really not want to go back to a pump which isn’t integrated with a sensor and making adjustments.

If anyone is considering the tSlim, I’d say go for it. It’s a very smart-looking and smart-behaving insulin pump. And it might really suit you well.

So why the switch?

Good question! With diabetes gadgets and gizmos over the years I’ve found that the devil is very much in the teeny tiny details. And that even something that’s brilliant, and well regarded, can somehow just not ‘click’ with you and your particular diabetes’ foibles.

This seems to be doubly true with algorithms.

An algorithm is based on a way they expect a person’s diabetes to behave. And how much of an adjustment that person might need to steer things in the right direction in any given set of circumstances. Your own individual diabetes may, of course, have other ideas. But commercial systems being what they are, they don’t really want to offer you much in the way of adjustment or personalisation. It is what it is.

Pretty soon after starting in the tSlim (with only Basal IQ at that stage) I observed that their predictive low-glucose suspend acted much later, and switched off much earlier than the one I’d been using on the MM640G for several years. There were a gradually phased series of basal reductions before a full suspend (really my body needs a full shut-off from the start), and the insulin resumed very soon after an up-tick in sensor values was seen. This was good in the sense that I didn’t have any of those occasional teeth-grindingly frustrating high BG alerts following an over-long suspend. But it was a bit rubbish, on balance, because only the most gentle downward-drifts were caught in time for me. Even when I activated ‘Exercise Mode’ for such strenuous exertion as wandering round to the shops.

In the old days I’d have set a Temporary Basal Rate to start things off early. But Hybrid Closed Loops don’t let your set TBRs, because... well... they are supposed to be doing all that stuff for you.

I experimented with setting essentially a fake TBR basal profile of 0.1u/hr for the 24 hours and activating that at the start of dog walks and such... But then, inevitably, I’d forget to switch back when I got home, because TBRs had always just cancelled themselves after a set time. Following an update of the Control IQ software I was able to completely suspend the pump for a defined number of minutes after which it alerts to restart. This was OK, but for reasons I cannot really understand this also silences any alarms of impending hypo/dropping BGs the pump might helpfully provide if basal-suspend isn’t enough on its own, and levels are getting a bit close to the edge.

Dex lag and alarm fatigue

Initially I was blown away by how well the Dexcom G6 tracked my BG levels. Whenever I did a ‘how are things going’ cross-check the results between fingerstick (Contour XT) and Dexcom G6 were only ever a few tenths of a mmol/L out. This gave me huge confidence. But at some stage in the first year I observed that the problems I was having with the late action of tSlim’s predictive low-glucose suspend were being compounded by a distinct lag between capillary glucose and sensor glucose. This isn’t news to me, and I understand exactly why this lag exists, but Dexcom seemed more reluctant to respond to changing values than any other sensor I had used. Almost as if part of it’s ability to match capillary glucose so well when things were stable was bound up in taking extra values and only updating sensor glucose every 5 minutes - perhaps it just waits until it's sure? For me Dexcom G6 is almost always a whole 10 minutes behind moving glucose. And when a ‘this hasn’t worked’ Control IQ alert is happening only 15 minutes before levels dip below 4.0 (and that ’15 minutes’ is what was happening 10 minutes ago) well... some of my increased number of low-level hypos were easily explained. From 1% below 4.0mmol/L to frequently more like 3 - 3.5% - still on target, but I've worked hard to restore flagging hypo awareness and this really can't help.

When is a 4.2 not a 4.2? When it's 10 minutes later

Added to that there were challenges at the other end too. I’d get told that the basal suspend wasn’t enough and to take preventative action after I was already low, and then 10-15 minutes later be told that levels hadn’t recovered, which prompted me to re-treat. Only to then discover that actually that hypo-treatment had been enough, and that the double-treatment was now gleefully pushing me into the teens. Maybe 5-minute updates 10 minutes behind reality are OK for some people - but when I really need to know how things are moving at the sharp end of hypo-dodging, they were causing me frustration and treatment errors.

The upshot was that pretty early-on I had to take the up reins of hypo-dodging myself again. I set my ‘low alert’ at 5.2mmol/L because (10 minutes behind), that gave me enough time to take action if necessary - with a sensor reading 5.2 and dropping I could easily be low 4s when the alarm sounded and need some rapid glucose to steer away from the 3s. I had the alarm repeat at 30 minute intervals, so that I’d get a reminder to recheck to see any action I’d taken had worked.

But of course it might be that I was just pootling along in the 5s. Getting little warbly nags every 30 minutes. Which was quite annoying.

Even more annoying

But nothing like as annoying as the tSlim’s attempts to actively sabotage my hypo-dodging efforts. Alongside a rapid resumption of the basal profile, the tSlim has, on multiple occasions, delivered a mini-bolus just as my levels were returning to safety after a hypo treatment(!). For meal mis-calculations, or dose-timing errors it never seemed quite so enthusiastic, or effective, at turning around a rising BG, but getting another low alert in the high-4s on a dog walk or while gardening, having successfully treated the last one - and then finding out that it was the tSlim that had caused it with a completely unnecessary mini-bolus, was the inspiration behind some particularly florid and lively outpourings of language over the past 4 years. I asked my consultant whether they knew of workaround/setting to prevent this. Alas none was available. So I had to hugely down-grade my correction factor during the likely hours of evening dog walk, which of course means Control IQ can’t work ‘properly’ during those times when dog walks have happened at other times. And again, setting or not setting ‘Exercise’ mode doesn’t seem to be the fix.

The hollow squares are tSlim autoboluses

 

Better results, but more effort

So yes, I have had better results, and the tSlim has handled many things really well for me. But the alarm fatigue has been pretty tough going. I’ve had a much higher numbers of non-severe hypos than I was used to on the MM640G, and I really miss the discovery that my pump has fixed something for me after the fact, quietly, in the background, with no alarms or notifications required.

Hopes for the MM780G

It was the memory of weeks and weeks with no sub-4 numbers that got me wondering about returning to Medtronic, and giving their hybrid closed loop a try. The pump is the same format, and the chassis is still as clunky and grim as ever (though I’ll be glad to have a screen that’s visible in sunlight again - the tSlim is awful in daylight), but they have updated the software, so it's not exactly like going back in time 4 years.

Medtronic G3 sensors never worked well for me and needed frequent calibration, including overnight. I gather the G4s were significantly better, and I have high hopes for the new Simplera sensors that I’ll be starting on.

I know quite a few people on the MM780G, and almost without exception they seem to get on very well with it. I know there will be frustrations and annoyances - there always are. But I’m hopeful I may be able to experience some of the “spending less lime thinking about diabetes” that others mention. On the tSlim I think I’ve had to think more - constantly checking up on what it’s doing, and fixing some very silly decisions it was making from time to time.

I’ll let you know how I get on.

64 Days with the Medtronic 640G: Ep 7 Overnight Hypoglycaemia

Those of you who can remember way back when this blog started (if you even exist, you have my undying affection for your extraordinary stickability) may recall that we were prompted to start writing a blog about my diabetes as a family after a particularly nasty overnight hypo. It was the beginning of me realising that I was *nothing* like as good at the whole 'pretending to be my own pancreas' lark as I had managed to convince myself that I was. I began to realise how much I didn't know, and that one event led me to connect with literally thousands of others wrestling their own diabetes into submission every day. My life, and particularly my diabetes management are very much the better for it.

Overnight hypos have been a bit of a recurring theme throughout my 25 years of living with type 1 diabetes. I am lucky in that I have never needed paramedic callouts, but there were many times along the way when Jane had to step in at breakfast time to 'bring me round' in the years before we started writing this blog. I look back at those early posts and am bewildered and ashamed that it took me quite so long to realise how much effect this was having on everybody else in the family. How unfair it was on them. At the time though, I guess I had convinced myself that my management was 'as good as could be expected'. I knew I was having 'A few too many highs... a few too many lows'. But doesn't everyone?

If you are the sort of person who approaches anywhere near 8 hours a night when you live with type 1 diabetes, you are spending fully a third of every day in the land of nod. That is an awful lot of time for things to go wrong - especially if your basal insulin dose is not adjusted correctly* or your requirements have moved since you last checked. You may be lucky enough to get clanging warning signs when you dip below 4.0mmol/L - enough to wake you up and sort yourself out. But you can't rely on them. And the more and longer the periods you spend below 4 during the night, the more of a hammering your hypo awareness will take and the less you will feel them. A classic vicious circle.

I am coming toward the end of my 64 days with the MiniMed 640G now (Medtronic have kindly allowed me to keep hold of their toy for a little while longer as there are a couple more posts I'd like to put together). Today seemed like a good opportunity to gather some of the snippets of video that I've been filming since the beginning and edit them into a 'SmartGuard vs Overnight Hypoglycaemia' post. Has Smartguard made any difference? Has my overnight hypoglycaemia reduced at all?

Watch the video below to find out what has been happening over the last 9 weeks. As always, I'd love to hear your comments or any questions, please leave them below or post on my Youtube channel.



*During the video, I mention how important I have found the concept of basal testing over the last few years, both on MDI (multiple daily injections) and also on a pump. Systematically testing and adjusting my basal insulin on an ongoing basis helps me to keep my meal doses and corrections working more or less as I expect them to (ha!). It was one of the most significant 'new concepts' I discovered when I first started comparing notes with other people with type 1 diabetes online. If you'd like to know more read this post by Gary Scheiner (Think Like a Pancreas) which explains the principle. It is written for pump users, but would be easy to adapt for once- or twice-daily basal insulin injection on MDI.

64 Days with the Medtronic 640G: Ep 2 The first 28 days' results

I wasn't expecting to be posting this blog today (well it seems like it'll be tomorrow by the time it has uploaded, but it's still today as I'm typing this). I had a vague plan that I'd do an introductory blog, and then move on to explain what SmartGuard was and how it worked. But today marks 4 weeks since I have been living with the MiniMed 640G and having looked at the results so far to say I am impressed is an understatement.

Ever since diagnosis, if I'm honest, I have preferred to run on the low side rather than on the high side. Lows were quick to sort out and usually involved eating something sweet and tasty, while highs took much longer to come down and, while they did not make me feel particularly grim like they do for many people, they also carried with them the spectre of all those diabetes nasties waiting in the wings. Blindness, kidney failure and amputation vs fruit pastilles seemed an easy choice to make.

Of course running on the low side and 'preferring' hypos is not a brilliant plan. My hypo awareness began to take rather a dent and I spent many years with significant hypo unawareness and the severe hypos that go with it, especially overnight. Looking back I am ashamed that I did not realise the pressure and stress that this placed on my whole family and especially Jane.

Pretty much since we began writing this blog I began to try to reduce my incidence of hypoglycaemia and regain my warning signs, and generally wrestle my diabetes into behaving itself a little better. I have put quite a bit of work in and learned a lot. Thankfully I have not had an episode of Severe Hypoglycaemia for something like 3 or 4 years now - long enough ago that I can't remember anyway. But for all the success there have remained a stubborn few dips under 4 (which may or may not be hypos depending on your definition) that I have been unable to tame.

This video blog examines what effect SmartGuard has had to my results in these first 4 weeks.


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Bubble, bubble, tubing trouble

Looking at my stats it seems Artoo has been having a bit of a run of form recently. Not without a wobble here and there obviously (let's not be silly) but certainly a decent punt at things on the whole, and far fewer eye watering levels in the 20s than in any of the months since I started on an insulin pump (which were never really part of my MDI experience). According to the funky monthly reports on my current BG logging app of choice (the excellent mySugr - 'making diabetes suck slightly less') my purple patch seems to date back to October. I even seemed to manage Christmas with fewer Quality Street induced gaffes than I would normally expect. Generally average BG in the high 6's low 7's (108-126), with an SD around the mid 2's (36). This makes me happy.

Aside from me taking a *very* long time to get used to the whole pumping business (Artoo was very patient with me) I believe there are a couple of changes which have helped me, so I'm posting this insufferably smug blog entry just in case there are any frustrated insulin pumpers who stumble upon it that are putting in all the effort but not seeing the results they are hoping for.

Firstly, September was the time that I switched infusion sets. I'd been having a fair few failures for some months, but only in amongst a majority of set changes that worked perfectly. At the time it was less obvious, but looking back, a readings/recoveries from mid 20s almost every month were messing things up for me. If you are getting set failures/site issues more than a couple of times a year it could well be worth asking your clinic/DSN/endo what alternative lengths and types of infusion sets are available to you. I've not had *one* site failure in the past four months - and aside from the lack of eye-frying levels, it also makes me feel a lot better about the whole business of diabetes day to day (as hard as I try not to part of me always takes these out of range disasters as a sort of personal failure).

Secondly, and my initial reason for writing this post, I think I have cracked the 'bubbles in the tubing' problem. Maybe not 100%, but pretty darned close. I'm not sure how common this is, but throughout my first year on a pump I was occasionally victim of a 'phantom bubble of doom'™. I'd fill the reservoir with room-temperature insulin as advised, having first moved the plunger up and down to lubricate the inside of the reservoir. I'd flick and jiggle for all I was worth until I was absolutely sure that there were no bubbles in the insulin. Fit the reservoir to the pump, and prime with the pump vertical, tapping all the while to ensure that any rogue bubble-ettes got expelled in the priming, and then connect everything up happy in the knowledge that I had achieved the perfect bubble-free set change. BUT. The next day, look at the reservoir and BAM, there it was a big, fat, lurking, bubble of doom. Ready and waiting to find its way into the tubing at some inconvenient moment and then effectively deprive me of basal for an hour or two. Or mess up a meal bolus. Or both. I do try to check my tubing a few times a day but these suckers are hard to spot. And just as frustrating as the high BGs they caused - was not knowing where they were coming from! I was as sure as I can be that they were not there when I changed the set. They just seemed to be emerging out of nowhere with an evil glint in their eye overnight.

I did discover a suggestion on You Tube, which I won't link here as it was a complete disaster for me. The technique (described as something like 'degassing the reservoir') involved creating a fairly strong vacuum in the insulin vial by repeatedly drawing air out of it until you could do no more. Do not try this! My experience is that reservoirs are just not designed to operate under that kind of pressure. On more than one occasion (and I only tried it about 3 times!) the o-rings failed and insulin began to leak 'behind' the plunger while the reservoir was in use. Complete BG chaos. But it did get me thinking...

If you too suffer from occasional 'phantom bubbles of doom' - here's what seems to be working for me. When you draw up the insulin into the reservoir it is usual to first inject air into the vial, equivalent to the insulin you are about to withdraw, to equalise the pressure. Instead of this only inject half of the air into the vial. Additionally you should make sure that you inject the air with the vial downward, then invert the whole caboodle to draw up the full insulin amount. Then flick and jiggle any bubbles that have crept in as normal. Disconnect the reservoir first, to allow the air pressure in the vial to normalise again. It seems that the very slight vacuum created is not enough to worry the o-rings, but is sufficient to make the insulin less 'aerated' in the reservoir. Or something. Anyhow, it seems to be working!

Obviously... Disclaimer, disclaimer. Not medical advice. Consult a qualified person. Don't try this at home. Read the documentation supplied with your pump. Simply reading this blog post may void your warranty etc etc.

If you have any top tips that you have discovered for yourself - please share them below :)

#teamsmug

One of my favourite diabetes-related hashtags of late has been the coining of #teamsmug (I'm not sure who came up with it, but I suspect it was either Dave or Paul). Part self-congratulation, part self-mockery, membership of #teamsmug can follow as little as a single unexpected good BG result after a tricky meal - even just waking up at a good level is enough. The shiny (and entirely imagined) #teamsmug baton is being passed around between Twitter users who know that a few good levels should be enjoyed, but can't necessarily be expected to last. Oddly enough, pretty much as soon as I had blood taken for my HbA1c I had an unusually prolonged #teamsmug period. Almost as if Artoo was responding to my previous grumpy post with, "Doubting my effectiveness are you... Well we'll see about that!"

It has been a hectic few weeks, and I really meant to post something about my HbA1c results before now. I was delighted (and slightly confused) to get a result of 46mmol/mol (6.4%), pretty much back to the last A1c I had pre pump, but with all the hypo reductions and general quality-of-life improvements that the pump has brought. It was a bit of a surprise to be honest. I'm not quite sure how I got that sort of result, as it certainly doesn't seem to fit with the weekly averages I'd been having in the weeks running up to my appointment. It just goes to underline the imperfect nature of HbA1c as a marker.

You'll be reassured to hear that my #teamsmug membership has been revoked since. Nice while it lasted, but the goalposts have moved again, and I'm still chasing after them with a few basal tests.