Posted by on Saturday 30 December 2017

CGM, diabetes time travel, and lessons learned from go-karting

Image by 'aurorasognatrice' used under cc.
2017 is hurtling to a close, and despite my giddy optimism about having 'loads of time' over the festive break to do all sorts of things that I don't generally get around to, the days have passed in a blur of hopelessly guestimated carbs, fun, friends, family and alcoholic excess. Consequently I am once again hastily cobbling together a round-up of the year type post - you lucky lot.

Almost exactly 12 months ago I was placing my order for a transmitter and first box of sensors for my MM640G insulin pump. I'd trialled the system over the summer of 2015, and I have always opted for Medtronic pumps with the vague notion of possibly, some day, self-funding CGM - but this was the first time our family finances had permitted it. I'd been using Freestyle Libre sensors intermittently for a few years (which you can use sporadically without the additional £500 for a transmitter), so I was interested to see how occasional SmartGuard coverage worked out for me.

In the end 2017 turns out to have been by far my most sensor-filled year. I was invited to trial Medtronic's Guardian Connect in April, and was unexpectedly and very generously gifted some short-dated sensors by someone who was switching systems and could no longer use them.

I always try to get the maximum use out of every self-funded sensor I insert, and I am fortunate to be able to restart almost all of them for at least another 6 days while retaining good performance. This almost halves the cost - or more accurately for me, doubles the sensor coverage. I had hoped to spread 10 'stretched' sensors (approx £500-worth) across the year to give me somewhat less than 50% coverage, but in the end, have been able to use them continually for quite a number of months which has been a very interesting contrast to my usual pancreas impersonation guesswork. It's interesting to reflect on the changes I've noticed myself making to day-to-day management decisions, and how it has felt as an experience. Here are a few basics:
  • On the whole it has felt far easier to live with diabetes this year.
  • I've not done any complex analysis of BG results, but my basic monthly spreadsheet analysis (nerd alert) shows significantly better results.
  • My A1c has fallen by 7mmol/mol (0.5%) and my hypoglycaemia has dropped significantly
  • Sustained reduction in hypoglycaemia has really improved the reliability and timing of my warning signs.
  • For the most part I seem to be operating with around 80-85% of results in range (4-9mmol/L) - even over Christmas. This is ridiculous.
  • On average I've only been getting 1-2% of results below 3.9mmol/L, nocturnal hypoglycaemia has been almost completely eradicated and I am having days and sometimes weeks at a time with all but no readings below 4.0.
  • These are not results I can achieve without continuous data, not matter how hard I try.
  • Even with the benefit of Freestyle Libre these are results I find it impossible to achieve. The alarms of full CGM provide me with significant added benefit, especially for catching lows.
  • Occasionally life with CGM has been rage-inducingly frustrating, and alarms have sometimes driven me to distraction.
  • I've had a few duff sensors and made some very poor choices based on inaccurate sensor data.
  • Additionally, SmartGuard is a bit of a liability with an inaccurate or under-performing sensor, sometimes sending me into double figures with a cancelled basal (and sometimes half of a slowly-delivered bolus!) when I would have been fine if left well alone.
  • SmartGuard is amazing for me, but very often I can't resist overruling it, ending it early and/or adding some carbs. Sometime this works better, sometimes I suspect I create more problems for myself than is strictly necessary 
  • Additional data is a significant help to me day-to-day. I've come to rely on it and feel quite lost without it, but there are times when some of the subtle details of life with CGM have created their own challenges - which leads me to...
CGM and diabetes time travel
I've always been one for a thinly stretched analogy. I can't help myself. There are two coming up... You have been warned.

With absolutely no apologies for the shameless 'Christmas Dr Who' reference, I've also been thinking quite a lot this year about the diabetes time travel that you get involved in when tinkering with continuous data. I've considered this before in terms of the repeated half hours you can spend with diabetes waiting for various management decisions you have made to start working - periods of waiting which can seem interminable. With more time spent in CGM-land this year I've noticed additional time travelling shenanigans with the lag between 'sensor glucose' read via interstitial fluid and actual 'what's happening now' blood glucose information.

This was brought more keenly into focus with my brief dalliance with the faster-acting Fiasp. An insulin surrounded by feverish hype of very rapid action - which sadly for me rather failed to live up to expectations. But the promise of faster acting doses has occasionally made me feel the sluggishness of Novo-not-very-Rapid all the more keenly.

Mostly I find 'sensor lag' is barely noticeable, but with a whiff of irony, it is when my BG is on the low side and I'd really appreciate accurate information that this 'time travel' is most clearly noticed. Looking at a Libre or Enlite trace at those times, shows you what was happening something like 10 or 15 minutes ago. And any 'rapid' carbs you take to bring up those low levels, or turn-around a dip towards hypoglycaemia won't change your blood glucose for 10 or 15 minutes, and may not show on the eagerly-watched line for a further 10 or 15 minutes after that. More than enough time to double-treat, only to watch your levels climb into double figures a little while later.

In just the same way, when you have a trace to watch, there is a powerful urge to see a high-and-rising BG trace turn around. But correction doses for me are unlikely to show any noticeable effect before 60 minutes have passed (unless I add increased activity into the mix) - plus the mandatory 10-15 minutes, of course. And at each of these moments the graphed time-travel of results, and interminably upward direction of travel gives few clues as to when it is 'just about' to level, or begin to dive downwards. Threepio proudly suggests 'insulin on board' from which you might think I could make an educated guess (and sometimes I do luckily seem to drag some precious clues) but all too often I can find my IOB dwindling away to nothing, coping only with mis-guessed carbs, rather than the elevated BG I had hoped to squash. Other times I can bear it no longer and wade in with an additional dose, only to see my BG trace drop off a cliff and plunge downwards - awash with both insulin and various types of carbs. Which reminds me...

CGM and lessons learned from go-karting
I have only been go-karting three times I think. By which I mean the crash-helmeted-boiler-suited-whiff-of-2-stroke-engines style go-karting rather than the sliding-down-a-hill-in-a-fruit-box-with-pram-wheels-bolted-on style. I don't think it's an exaggeration to say that I'm absolutely terrible at it. I was reminded of my go-karting prowess when thinking about some of my... erm... more questionable diabetes decisions in response to a more frequent CGM data-feed. I suspect I am not the only one who has fallen foul of the double-dose and/or double-treat temptations - and for all the benefits of all that extra information, it is unmistakeably one of the risks.

The very first time I sat in a go kart, in a dimly lit, oily, industrial shed on the outskirts of our city, my driving style was essentially binary. The accelerator was either fully down or entirely untouched. The steering wheel locked at either edge or dead centre. Brakes were applied with sledgehammer-like gracelessness. As a result I kangarooed around the indoor circuit, making full use of the amply-supplied tyre walls and doughnuting my beleagured kart in furious circles. I proceeded at lightning speed from one collision to another and made very little effective progress around the twists and turns of the circuit.

This is pretty much the way I drive my diabetes when things are not going well. Frustrated by apparent lack of action of more reasonable measures I heftily over-correct with hugely inflated insulin doses or swigs of Lucozade. Lurching and stumbling from high to hypo and back again. Crash! Clonk! Screech! Everything becomes overblown and chaotic.

The second time I went karting was every bit as 'successful' as the first, but I had something of a lightbulb moment on the third occasion - which was at an outdoor circuit. For whatever reason, this time I adopted a more subtle approach. The accelerator was rapidly pressed full down at the start, then backed off in time for the first corner... rather than stamping the brakes I found myself making little feathered dabs. Steering was altogether more considered. Confidence grew. Speeds into tricky corners increased, a late firm braking followed by a hard turn of the wheel and full throttle at the mid-point of the turn allowed me to power-slide out of the corner. I was still making strong adjustments in some circumstances, but more often my choices were much more subtle, more measured.

This is what I see when my diabetes management is more successful. It is when I am able to make smaller adjustments that I do better. Multiple big overlapping doses and rapid-carb 'rescues' can leave me in a flat spin and going nowhere. Smaller tweaks, spaced further apart are often significantly more successful. I have found this to be a really interesting and important thing to think about when Threepio is merrily warbling away. Those alerts can seem equally frantic, but I need to pause and consider my position on the 'circuit' of my day. Can I just coast through this corner without stamping on the brakes (adding insulin) knowing that the turn of the wheel or dab on accelerator I've already made is enough, or is this the devious hairpin and do I need full-lock and firm braking before powering-on with additional carbs to make the turn.

In general terms, when I notice that I am oversteering and stamping on the brakes and accelerator of my diabetes managment, I am trying to remind myself to make a couple of slower laps and build up to speed again more gradually with more gentle adjustments.

Widening the access to continuous data?
I was delighted to be invited by Abbott to attend DxAmsterdam in July, and then in September the eagerly awaited news was released that Libre was to be placed on the NHS tariff and could theoretically be made available on prescription, subject to local CCG decision-making (and perhaos an emerging postcode lottery). Abbott's real-world data, shared in Amsterdam, backs up my own experience of access to continuous data - that the more information I have on which to base my guesswork, the better things tend to go for me.

Diabetes still has the capacity to be hugely annoying of course, but for me - more data certainly leads to better results. Continuous data is not without its challenges, and it will be vital for people living with diabetes to be given appropriate support and help in order to make best use of the information and avoid the pitfalls. Both in terms of their support from their clinic and also perhaps, those who have made the mistakes before them and can share their experiences. It will be really interesting to see what effect wider access to these technologies delivers as access to Freestyle Libre and CGM increases in the years to come.

It remains to be seen quite how much life my transmitter has left in it. They are warrantied for just 12 months. I will continue to use Enlite sensors for as long as I can, especially since my CCG seem rather reluctant to take any decisions on the finding of any kind of sensors for anyone - however great the need. I would imagine I would be very far down any list they eventually decided to draw up. After that I'm not sure if I will revert to Freestyle Libre, spring for another Guardian transmitter or take a continuous-data break.

Wishing you all a tip-top 2018. And thanks as always for reading.

Posted by on Saturday 2 December 2017

Keya Smart Meter review - Ketone and BG results in a single strip

Every once in a while, some device manufacturer or other drops us a line to see if we'd like to take a look at their fancy new gadget and see what we think. When it comes to blood glucose (BG) meters, it is very rare that something genuinely new comes to the table, often it's just a cosmetic way of getting the fingerpricker, strips and reader in one amorphous gloop of plastic - a fascination which escapes me. A couple of years ago, at a diabetes conference I had somehow managed to get into (not at all easy if you lack a medical qualification) I was struck by a display in the exhibition hall advertising a new BG meter, that seemed to break this mould, and be offering something new and really rather interesting. The ability to get blood glucose AND blood ketone results from a single strip. A strip that would be priced more or less in line with the general BG meter market.
For those mercifully unaware of the significance of that, blood ketones are generally regarded to be a Very Bad Thing if you live with type one diabetes. If left to build up in the blood due to insufficient insulin and raised BG they can quickly turn a normal day into one filled with paramedics, wailing sirens and everyone's second favourite urgent diabetes complication - Diabetic Ketoacidosis (DKA) - which, joking aside, is potentially lethal.

Ketones not keytones
Keytones are the annoying bleeps your phone makes as you type, unless you have the good sense to switch them off. Ketones take annoying to a whole new level and might easily send you scampering to A&E.

Ketone monitoring is generally advised for people with type 1 during periods of illness, or if BG levels become elevated (say above 13mmol/L / 230mg/dl) and remain there for any length of time. For some people on insulin pumps, ketones can be particularly problematic, because a blocked cannula or bad infusion site can leave little, if any active insulin after a matter of hours. I am lucky in that I do not seem to create ketones as readily as some, but I know that for many, especially parents of children with T1, ketones are a real source of anxiety and worry.

There are two ways to check for ketones, one is through urine strips, the other blood ketone monitors. Urine ketones offer a significantly delayed picture because it takes ages for them to filter through, and blood ketone strips until now have been fiercely expensive (approx £2.50 each strip) which means that those who secure them on prescription usually only have a limited supply, that they must use carefully when they need them most. But here was the promise of a meter that would give an instant blood ketone check, effectively free of charge, alongside every single BG result. This was a genuinely exciting prospect and I asked the Keya Smart folks to keep me informed.

It took a while for them to send me a meter to look at, but here is my n=1 experience of the Keya Smart. I can't say how it would work for anyone else, but this is what happened when I tried it out for a month.

Left to right: AccuCheck Expert, Contour NextLink and Keya
Pouch, pricker, strips and basics
One of the first things I noticed was that the case for the Keya Smart was a bit on the large side. The meter itself has a good sized touch-screen which is bright, responsive and easy to read. There is a USB cable/adapter for charging and data transfer, though data transfer can also apparently be done via Bluetooth - a feature which I did not investgate. The fingerpricker is perfectly serviceable and fairly pain-free with adjustable depth, but is not going to snatch my affections away from my trusty Multiclix. The strips, unusually in my experience, come in a flat container which nestles neatly in the pouch. This made strips extremely easy to remove when the container was full as they lined up like soldiers, but as the tub emptied the strips were able to slosh about a bit more and became a little fiddlier to remove. One nice design feature of the pouch was that the meter say inside four little 'corners' which neatly held it, but also allowed you to easily remove and replace it whenever you needed and also access the touch-screen completely unhindered. None of that faffing about with elasticated transparent bands.

Set-up, battery life and data display
You are walked through a basic set-up when you first switch the meter on (time, date, language and so on). You can then set glucose targets and activate other functions as you need them from the 'set-up' screen - for example whether you would always like to see blood ketone results, or only be alerted if they are elevated.

The battery seemed to last well - I would guess I'd get a good couple of weeks' use before I needed to recharge. The large screen must take some juice, and rather strangely there did not seem to be a way to turn it off when finished, you had to rely of the screen timing out and switching itself off after a few seconds. Pressing-and-holding the 'On' button didn't seem to do anything. This might be a bit annoying if you were running low on battery when out and about and needed to squeeze a few BG checks out of it until you could recharge.

The meter stores results for both BG and ketone results which can be viewed in a logbook table, or averaged over 7, 14, 30 and 90 days. I particularly liked the 'trends' screen which allows you to view results for either BG or ketones in a pie-chart style over 7, 14, 30 or 90 days.

You can flag results as being before or after meals, fasting, during sickness, for exercise or with insulin. These flags can then be applied to your 'trends' view to filter your results and see how your numbers stack up for those different times of day/activities. Importantly for me, you can add or edit those flags whenever you want to, there is no time limit. You can go back and add a meal tag several days later if you forget on the day. It frustrates me beyond belief when diabetes gadgets set arbitrary time periods for these kinds logging options. They are my data - I want to be able to access and update when it suits me.

Ketone values are highlighted either each time you check BG or only if elevated (amber) or high (red). Ketone values of up to 0.6mmol/L are considered fine, between 0.6 and 1.5mmol/L rates as 'Elevated' and any ketone reading above 1.5mmol/L is flagged as 'High'.

Build quality?
It all seems pretty slick and solid to handle (with the possible exception of the finger pricker which feels a little flimsy), but I did have an unfortunate time with my first Keya Smart meter which stopped turning on after about 4 days. Neither the strip port, nor the on button, nor recharging would bring it back to life, and there was no way to extract any data from it that I could find. It was fine one evening and just would not turn on the next morning. It was an ex-meter.

Possibly the most annoying error screen, ever.
One aspect I always enjoyed reading in Tim and Alison's meter reviews on the venerable and much-missed Shootup related to strip slurpiness. How keen, or otherwise, a BG strip is to avail itself of a proffered droplet of blood. Sample size for the Keya Smart meter is a piffling 0.5μL, but unfortunately the strips themselves are rather bashful in welcoming your freshly squeezed fingers. It takes my Contour NextLink less than a third of a second to slurp up it's required sample, and the strips hungrily home in on blood from half a room away. By contrast the Keya Smart meter took a full 2 seconds, and seemed to need you to place your finger in a very precise alignment before it would deign to begin its dainty sipping. Not only that, but there was no opportunity to 'have another go' if a sample was fractionally short, as there is with some meters. Not quite enough blood on a strip and you had to abandon the check, and start again. Even more annoyingly, given it was completely outside of your control - the meter would reject some tests because the strip was filling too slowly - to which I would frequently shout, "I KNOOOOOW!!".

What was very unfortunate was the frequency of these strip errors. I don't know if I was just unlucky, or if it is something to do with the engineering of the strips to allow the dual results, but I was having significantly more checks rejected by the Keya Smart than by any other meter I have owned. Particularly irritating when you had a slow fill error, followed immediately by a underfilled strip error, before you finally managed to get a result.

Elevated BG, but ketones 'all clear'.
Again I must stress that these are just my n=1 observations, but while I was using the Keya Smart I decided to check against my current NextLink USB meter. I often do this when evaluating a new piece of BG technology, because it helps me to know whether the new one generally reads higher or lower than I'm used to which can help inform my BG management decisions. The NextLink USB was said to be one of the most accurate on the market in a recent review, and I have always found it to be very reliable when double-checking a value, rarely differing by more than a few decimal points if I am not sure of a BG check and want to make sure it's not a rogue result. The official results in the Keya Smart handbook look similarly impressive with 94% of results within 0.8 mmol/L of a lab reference.

Sadly this was nothing like my experience.

Alongside BG comparisons, I also acquired a handful of Optium Blood Ketone test strips for my Freestyle Libre to cross-check any occasions where the Keya Smart meter registered elevated ketones.

Disappearing ketones
On multiple occasions I would recheck a value from the Keya Smart, only to be given a completely different number from the previous strip. Both blood ketone and BG values were subject to significant variation between two strips, checked moments apart. If either (or both) of those rechecks involved strip rejection(s) you can imagine the florid and colourful language which freely flowed.

Here you can see an initial check which alerted for high ketones despite in-range BG, by contrast the Libre shows only a trace of ketones. A recheck with another strip and while the BG value is very similar, the ketones have now dropped from 'A&E here we come' to 'Nothing to worry about here, sonny'. 

It did seem odd for me to get a high ketone alert at 4.0mmol/L BG, so this was easy to spot - but if it had been the earlier photo where I'd run in double figures all night I might easily have taken the first value as accurate. I have to say that in all the elevated/high ketone results I cross-checked, all the subsequent Keya strips and the Libre blood ketone checks only registered a trace.

And so, within a few days of using the Keya Smart, I had seen enough rogue values of either BG or ketones which had come out very differently a second time around that I knew that any value that was even slightly unexpected needed to be rechecked.

Keya Smart reads almost double.
But it's not always quite as easy as that in the day to day business of pretending to be your own pancreas. Sometimes you almost expect to get a high value. And sometimes the difference between Keya Smart and other glucose sensing technologies I was using at the time were actually quite alarming. If I had corrected for 12, when I was actually 6.8, then my correction dose, based on the data I'd received from the Keya Smart (had I not rechecked), would have aimed to send my blood glucose to 0.8mmol/L.  

That is more than a little worrying.

Keya Smart vs Contour NextLink - BG readings

NextLinkKeya SmartAvg +/- %

(against NextLink)
Avg +/- mmol/L

(against NextLink)
Distribution of readings
Number of readings where Keya Smart higher3682%
Number of readings where Keya Smart lower818%
Number of readings equal00%
Number of readings within 0.5mmol/L1739%

The table shows the results from 43 pairs of readings. Not a huge dataset, but the differences are quite marked. The Keya Smart almost always reads higher, sometimes significantly so. And only 4 times out of 10 does it read within what I think of as being the benchmark for 'pretty much the same' - less than +/- 0.5 mmol/L.

I really wanted to like this meter. There's a lot about how it has been put together that I really like, and the promise of 'ketone checks every time' I see as having real value for many people. Sadly though, the variability in the results I got means that it really isn't the meter for me. I will keep it and use up the strips I have for blood ketones as and when I need them, but I'll make sure I check three times on each occasion so that I can be sure of the result I'm getting.

I wish Keya Smart every success for the future and hope they can iron out these wrinkles for their next version. At the moment though, this feels like it's a product that's not quite ready for the real world.

Final verdict: 1/5

Disclaimer. I was offered a Keya Smart meter and sent it free of charge. I was not asked to write about the Keya Smart meter and I've not been paid to write this post or publicise the product in any way.