A Medtronic 670G Diary: Start-Up Week

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Several months ago, when my A1Cs climbed out of their usual range of 6.5 to 7.2 up to 8.0, my endocrinologist suggested that it might be a good time for me to consider a continuous glucose monitor (CGM) in combination with the next generation of insulin pumps. I was open to upgrading my old Medtronic Paradigm pump; it was well worn. I felt tentative to the point of avoidant at incorporating a CGM into my care. Would I get the results I wanted? Was it doable? Could I handle being connected 24/7 to another device? I had been ultimately disappointed by a short trial of the Medtronic/Enlite system. My doctor reassured me, “The new technology works really well. The benefits will make the adjustment period worthwhile.” I opted for the new Medtronic 670G system, which combines a pump with a CGM with new smart features, including auto suspend, which temporarily halts the basal insulin when blood glucose (BG) dips too low, as sensed by the CGM.  To simplify things, it means this: the CGM and the pump “talk to” or communicate with each other directly.

After much thought – and with me, every decision requires much thought – I said yes to the new. Curious about both my experience of and thoughts on a pump-and-CGM system and what it means to my health and life, I started to take notes. Weekly, I’ll share that chronicle with readers of ASweetLife. Here is Week One.

Monday night: I’ll call this “The Day Before.”  I open up all the packages related to my new 670G and sensor/transmitter that came in a multi-part shipment from Medtronic. I familiarize myself with all the parts.  Like a good student, I read the pump trainer’s email again – thank goodness – to remind myself of the homework.  I do some of it, but not all of it.  Most important is to charge the transmitter and the BG meter from Bayer, the Contour Next Link that works with the pump.

All the boxes are like an island in the middle of the living room rug.  The dog Winston does a circular pace around this island of diabetes equipment, again and again. He seems anxious to me.  I wonder if I am projecting my own anxiety, not really acknowledged, onto him?

My daughter Lydia, who is 22 and lives with me, asks: “Are you excited?”

I answer, “Not really,” surprising her.

“Why? It’s new technology,” she says enthusiastically.

I reply, sighing, “It’s more hardware.” Inwardly I add these words to the sentence, “… on my body.”

Tuesday: It rains in Boston, a deluge that is an effect this far away from Hurricane Florence. I drive to my appointment with the pump trainer, and my feet and sandals are soaked as soon as I exit the car. Water streams across the asphalt of the parking lot.  I resign myself to getting wet, and I hold my big bag full of Medtronic packages under the umbrella.

Eloise and I work together on the training for more than two hours.  It goes steadily. There is a lot to learn, including the insertion of the CGM sensor, the taping it down, the clicking into place the small clamshell-like transmitter. Step by step I do it.  There is no pain, just the hesitation of wanting to do it right. 

The pump itself has more controls and a more detailed user interface. The 670G has some closed-loop features to it. Over time, as it “learns” my glucose and insulin patterns from the data it gathers when I check my BG and enter carbohydrate grams and confirm the bolus, the 670G system will be able to control the basal rates and suspend insulin when my BG starts dropping too low at a fast rate.

Eloise encourages me to check my BG frequently, and calibrate the pump using the BG value from the meter three to four times per day.  “The system is learning about you.”  That word “learning” is the right metaphor, and yet it also conveys a kind of intimacy to me.

Later at home Lydia asks me how it went.  “Good,” I reply sincerely.  I tell her I feel much more at ease; knowledge is comforting to me.  She nods.

Wednesday: At 5:10am, the pump wakes me up to calibrate! OMG, will this happen every day this early? How can I change this, I wonder.

By dinner time, I’ve checked my BG at least 10 times that day, and the bottle of test strips I opened yesterday is almost empty.  This is about three times my usual rate of testing BG. I feel tied to this thing like a baby.  Will I be checking my BG this often, forever?  Maybe, I hope, this is the machine’s learning period, and once it knows enough its demand for data will taper off.

At work, I spend most of the day in my office on a writing project.  When the pump alarms goes off for various prompts, or when I am eating, I have the privacy of my office, not exposed yet to others.

I go out to dinner with a man I have recently met.  He has found and read some of my prior writing about diabetes, and he seems very calm and accepting. I am both touched and unnerved. At least I do not have to explain anything when I take off my pump from my waist band and enter a bolus.

By the time I go to sleep on Wednesday night, I have checked my BG 25 times in 35 hours.

Thursday: The pump asks me to calibrate.  It asks me if I want to bolus.  Alarms beep when it goes into Auto Suspend mode, turning the basal off because the BG value is approaching 70 at a fast clip.  I drink a juice box. I eat a rice cake.  I do not re-start the basal because I check my BG and I’m still too low: 70.

Later in the afternoon, of course my BG rises too high, rebounding from the low.  I do a correction bolus using the pump’s Bolus Wizard. I give it the info; it does a calculation based on BG and the correction ratio and sensitivity factor I programmed into the pump when Eloise and I initiated it.  I confirm the bolus.

Because I had Medtronic Paradigm pumps for at least 10 years before getting the 670G, I understand the basic terminology and operation of the insulin pump. With the Paradigm, though, I did all the thinking and problem-solving, and I relied on my BG values or physical symptoms, like sweating or wakefulness, to alert me to hypoglycemia so that I could eat a snack or suspend the insulin.  Now the pump with CGM system is doing some of this for me, standing in for me and my brain as master controller.

In only three days, I notice that the values the Medtronic CGM senses for my BG are getting closer to the ones I get from the Bayer glucose meter I use to check my BG. On the graph on the pump itself, I can see that my numbers are mostly inside the band of 70-180 that Eloise and I pre-set as the aims for control. “It’s working,” I think.

Friday: Today I leave work at 1pm and head north in the car to Maine, to see friends vacationing there. It’s a long drive, and I bring apples, cheese, and iced coffee to snack on. I stop at the LL Bean in Freeport, the original one, and I check my BG in the car before I go in. For the last 10 miles, I felt the vibration of the alert and heard the electronic ping, reminding me to check.  The number is 159, and I’m satisfied.  The pump quiets down, thankfully. Its little nudges and voice can be irritating.

My friends Marcia and Steve are generous hosts, and we drink wine, eat a snack, and sit down to a meal of chicken and a Greek salad. For dessert there are apples and cookies, and I have one of each.  I don’t feel like I am over-indulging but my pump under my clothes is vibrating and pinging. I ignore it mostly.  I say to my friends, “I have a new pump, and I’m getting used to it.”

At bedtime, my BG is high: 289. I do a correction bolus and go to sleep.

The pump wakes me in the night, two times about four hours apart.  Both times my BG is still high, close to 300.  Not sure what is happening, I correct each time. The pump can shut off when my BG is too low, but it does not correct when I am too high (or 250+).  I think this is a smart safety feature. A human mind is still needed to make the decision about when to add insulin into the body. The Auto Suspend function can protect a human who may not be aware that BG is going too low.

Saturday: It’s hard to be learning the 670G system while on vacation, even though I’m not too far from home, and I have all the conveniences and good food nearby.  Vacation and friends are distracting, in a good way, and the pump and CGM system needs attention.  I’m giving my attention to the view of the water from the house, the small coastal communities we drive and walk through, seafood and a cider for lunch, and an afternoon nap.  When the pump calls for me, I make it wait. Life is more interesting than it is.

Before dinner, the pump alerts me that insulin is not being delivered.  (My old Paradigm pump would do this too.) The 670G goes further and recommends on the user interface that I change the insertion set or take an insulin injection.  I change the set, and because I make a mistake with placement I change it again within five minutes.

On any given day, I interact with the 670G system for about 45 minutes total. But it feels constant.

Sunday: My morning BG, which is also a calibration value for the pump, is golden: 122. This seems like a great start to the day, a sign that managing the pump will be smooth. Starting off at a good baseline, for anyone with Type 1 diabetes, makes a day of insulin, eating, activity, and BG go better.

A good baseline number is also motivating. I want to maintain it.  For breakfast, I focus on coffee and protein (eggs). I have a slice of toast and bolus enough insulin to cover it. I check my BG again before I get into the car to head home, and it’s a tidy 167.

Long car rides are good times to think.  I reflect on my first week with the 670G system, and I realize that I’m going from BG to BG, bolus to bolus, alert to alert.  I’m not really noticing patterns, but that’s because I’m not really in the frame of mind to pay attention at a longer time scale than what is happening in that moment.  In the week ahead, I want to have set some mental goals of my own related to diabetes, as well as the numerical ones established in the pump.  I also know that I’ll have to change the sensor all by myself, with no pump trainer on hand to walk me through the steps.

Stay tuned.

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Jeff Nobles

Thanks for sharing this experience with the 670g–I’ve been using it since January and it’s generally a positive change. Sometimes it gets hinky, especially when changing the sensor. It sure helps to read how it’s working for you. Good luck!

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