SmartGuard Activated - Dual Wave Bolus Cancelled

Janki has a lot of slow and delayed release carbs in her diet: that's just the way it's always been and, in the spirit of Little D, we've tried not to make too many changes since diagnosis. It's one of the reasons we were keen to move to the pump - anything other than a normal (single) bolus is difficult with pens. Not difficult, painful. "Painful" for Janki and for us as parents. We did the bolus after meal thing, occasionally split the dose in two injections, but really, at three, when you're trying to stay relaxed about healthy food and diet, that gets tricky quite quickly.

So roll on the 640g, complete with Square Wave and Dual Wave bolus options, all nicely bundled into the Bolus Wizard.

I'm sure most of you are familiar, but just in case here goes:-
Normal - Delivers a single bolus of insulin immediately
Square Wave - Delivers a single bolus evenly over an extended time period (0.5 - 8 hours on the 640g)
Dual Wave is simply delivering the bolus split between a Normal (now) and Square Wave (extended, but even) delivery.

I don't intend to go into the details of what we've found works, or doesn't work, for Janki here, other than to say having the CGM data to look back on, rather than BG readings a few hours apart is a godsend. Previously it was a nightmare sorting out some sort of system with Pens and BGs alone and it's a shame we have to pay for the CGM side of this coin to get the information we really need. I can see us using Dual Wave quite a bit once things settle down.

By the way, I love the phrase in the Medtronic System User Guide on the Dual Wave:-
"A Dual Wave bolus can be useful.... when you eat meals with mixed nutrients, such as carbs, fats and proteins that are absorbed at different rates" 
That might just be every meal then (except maybe most breakfasts!) If her grandparents read that line, they'll insist on checking our logs for Dual Bolus events to make sure we're feeding Janki a healthy, balanced diet ;-)

Ok, so why the post..? On Saturday Janki had one of her favourite meals, which includes lentils, rice and a little fat. We know from experience, that Janki gets a fast glucose rise, followed by a prolonged release from the butter and lentils.It's also a dish that Sonal has meticulously carb-counted from scratch and we've dealt with on the pens many times.

Janki and I went out in the morning to get shopping, go to the park, do some scooting, all great in trying to get her post-breakfast surge down (after almost two weeks of experimenting, we think we may now have breakfast under control, but as you'll see, it clearly wasn't on Saturday...). I'd seen some arrows down on the pump display but we knew we'd pull it round with this lunch - she loves it and the fast carbs hit quickly. So down she sat, we bolused for the meal and delivered as close to 50:50 Dual Wave as possible in the Bolus Wizard (with the Square Wave delivered over two hours).

All good, food going in, Normal Bolus delivered. And then, four minutes later, we got a Suspend on Predicted Low Alert. As Janki was busy eating with the pump now tucked round her side, we left the pump to do its thing. Janki was fine, carbs flowing in. Thirty-five minutes later, Basal delivery was resumed, just as she was finishing up her meal and ready to tackle some fruit (with a separate bolus).

In the afternoon Janki's BG initially steadied and then climbed up, way higher than we thought they would. Fortunately Ketones stayed in check, but by mid-afternoon we decided to correct. So what happened, what went 'wrong'? What happened is available in the Carelink report:

Suspend Before Low Alarm
SmartGuard (Suspend Before Low, Subject NOT Responsive)
Bolus Cancelled: The in progress SQUARE portion of a DUAL was cancelled. Reason: Alarm

We didn't scroll through and acknowledge the initial suspend message (due to limited access and a content three year old). By the time the pump had resumed, a new message was displayed to acknowledge the resumed basal. So virtually all of the Square Wave (extended) bolus was lost and never delivered. Hence an afternoon of highs...

Of course, this is our fault, not the pump's. The Suspend Before / At Low features both suspend 'insulin delivery'; it was doing its job. However, having done my best to digest the nearly 300 page System User Guide, I had assumed I'd get a "Resume Dual Bolus?" message along the lines of that received when something else (e.g. battery change) interrupts a dual bolus (for up to ten minutes).

I certainly don't see any explicit warnings around bolusing in System User Guide and maybe that's something that could be clearer, particularly for people choosing to allow the Suspend Before Low feature to activate without an audible alarm, who may not realise an extended insulin bolus is not just suspended but cancelled altogether.

Of course, this is not something we're likely to repeat - it's now clear in our heads:
Suspend Before / At Low will suspend basal and cancel an extended bolus. 
We need to manually go back in after basal has resumed and put in a revised Square Wave bolus if necessary.

I hope this helps someone else avoid a similar mistake.