670G in Auto Mode: Forget What You Know about Pumping | Diabetesnet.com

670G in Auto Mode: Forget What You Know about Pumping

As I drove to my training appointment, ready to put the 670G into Auto Mode for the first time, I reflected on my past week in Manual Mode. The Suspend Before Low feature was a real winner with me, cutting off my basal delivery before I went low. I’d also noticed a big improvement in the accuracy of the sensor, giving me confidence to let the pump take over control in Auto Mode.

I walked into the doctor’s office, excited to start. I sat down with my educator, went into the pump menu, scrolled through a few submenus, and turned on Auto Mode. The first major difference: where did the graph go? The pump screen now displayed only a big blue shield surrounding my current sensor glucose reading in large white numbers.

We went over a few of the basics. My carb ratios would remain the same for now. Yes, you still have to bolus for meals, which makes sense. It’s like giving the pump a heads up that you’re eating. Insulins and sensors aren’t fast enough yet to figure that out and respond in time. But the rest of the time, I knew that the pump would raise or lower my basal rate depending on my sensor glucose reading.

Assuming that we’d give it a starting point and it would adjust from there, I asked what my initial basal rate would be. “You don’t have one,” said my CDE. Wait, what? “It’ll give you micro-boluses every five minutes, based on your CGM reading,” she explained. It took a few minutes for that to sink in. I’d been on a pump for less than a year, so I imagine it’s even more mind-blowing for long-time pumpers. Throw the concept of basal rate out the window.

There are other big differences in Auto Mode. There’s no option to do a manual bolus. If you’re high, take a blood sugar reading and let it do a correction bolus for you. There’s also no option for square-wave or dual-wave bolus, and no option for increasing or decreasing basal rate. Instead of decreasing basal for exercise, use Temp Target. It’s a one-size-fits-all option that raises your target—the sensor glucose reading your pump is trying to maintain--from 120 up to 150, for any amount of time you choose, in half hour increments. You could also use it in situations when you want to be extra cautious, like while driving long distances, as my educator pointed out.

But what if you want to increase your basal? Say, for stress, illness, or any other variable you know will raise your blood sugar? Theoretically, the pump would do that automatically. But I’ll cover that in a future post.

My educator told me the pump would start out conservative and tighten up later, for safety. Speaking of safety, if the 670g is delivering minimum or maximum basal for several hours, it’ll drop out of Auto Mode and into Safe Basal, where the blue shield will turn white. “What is my minimum or maximum basal?” I asked. Once again, there is no answer, at least not one that I can access. It’s all determined by the pump. In Safe Basal, it delivers your last known basal rate, which, once again, only the pump knows. There are also other safeties built in. If the pump thinks that something doesn’t jive with your sensor readings, it may ask you for several blood glucose readings. If things still don’t sit right with it, it’ll drop into Safe Mode or even back into Manual Mode.

Every six days the 670g reevaluates what it has learned about you, which means it becomes smarter as time goes by, and customized to you alone. I imagined a symbiotic life form attached at the hip, studying me. Kind of creepy, but at least in my mind he was a friendly and curious little guy, on a benevolent mission to equalize my blood sugar. He sure had his work cut out for him, being blind, deaf, knowing nothing else except my sensor glucose reading and the few basic inputs I could give: I’m eating this many carbs, right now! I’ll be exercising for the next two hours!

As I walked out of my training appointment, I pondered all of the changes. I realized I had to be scrupulously honest with this machine if I wanted it to learn about me. All of the ‘cheats’, second-guessing, and workarounds that are second nature to insulin users—cutting back a mealtime bolus based on a planned hike afterward; bolusing but then waiting to eat for a sugary meal; waiting until after a meal to bolus if blood glucose is low; using square-wave boluses for high fat meals or drawn out snacking; and myriad other combinations based on a multitude of factors--would end up being counterproductive if I wanted my ‘little buddy’ to truly understand me. And isn’t that what we all want, to be truly understood?

Next time I’ll cover the ups and downs of my first weeks in Auto Mode.

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