Anyone touched by type 1 diabetes has to be excited about the FDA’s recent approval of the first pre-Artificial Pancreas system, the Medtronic Minimed 670G. It’s a milestone towards ever-more-sophisticated automated insulin delivery!
Today, we’re thrilled to have our correspondent Wil Dubois walk us through a hands-on initial review of this exciting new system.
Everything about Medtronic’s new Minimed 670G hybrid closed loop insulin pump is so different that it requires a substantial shift in mindset. Like one of those team-building exercises where you cross your hands and fall backwards, counting on your peers to catch you, the 670G requires us to let go of elements of diabetes control that for years have bordered on sacred.
Why? Because this pump isn’t like anything we’ve ever seen before. In fact, it isn’t like any diabetes therapy we’ve ever seen before.
What the 670G Does and Doesn’t Do
How many times have you started your day high, even though you went to bed on-target and haven’t eaten for 8, 10, or more hours? How would you like a pump that could see you were drifting up while you slept, and just automatically gave you more insulin to fix the problem? Or a pump that could see that you are drifting down during a hard day’s work and shut off the flow of insulin to prevent a low?
That’s the promise of the 670G.
It’s designed to track changes in your blood sugar via a CGM, and keep you in target by automatically delivering “micro boluses” or withholding insulin—replacing a traditional fixed basal rate. All 670G users need to do is count carbs and enter them into the pump when they are going to eat.
So, how well does it live up to its promise?
OK, first things first. The pump’s target is 120 mg/dL and can’t be set lower. Personally, I have always used 100 for my target. And while the pump has a target, it really views its job as keeping you “in range,” which is a different thing. That range is 70 to 180 mg/dL. In my first week using the automatic delivery functions of the pump, I had fewer and shorter excursions than I typically saw using MDI—which was great—but the pump only succeeded in consistently keeping me at the top end of the range—which wasn’t great. After downloading my data to Medtronic’s CareLink software, I could see my blood sugar average for the first week+ was 170 mg/dl, which would equate to an A1C of 7.6—not exactly horrible, but hardly stellar.
Of course, the algorithm that drives the system is “smart,” meaning it learns and adjusts and adapts as time passes. It may get better, and, in fact, my sense is that over the last few days, the 670G been successful in pulling me lower within the range.
Familiar Modes No More
In a perfect world, the 670G would always function in automatic mode, making adjustments based on feedback from the CGM. But what happens when a sensor craps out? First, the pump drops into what MedT calls “Safe Basal,” where the basal delivery is given based on the pump’s experience. Simply put, if you knocked off a sensor at midnight during wild sex, the pump will fall back on giving you whatever amount of insulin it typically gives you at midnight. It will do this for up to 2.5 hours, and then if there’s still no CGM data flowing, the 670G drops back to manual mode, delivering whatever basal rates are programed into the pump.
Remember when I said you need to adjust your mindset to use this pump? In auto mode there are no more…
- Basal rates or temp rates
- Square or Dual Wave boli
- Bolus overrides
Why? Those are all features that let users exercise more control over pump operations, and that flies in the face of an automated system. To ensure that we don’t take the pump for a joy ride, MedT engineers have taken away the car keys.
Hands-on Pros & Cons
MedT is proud of its new and different form factor, but at first glance, my 15-year-old said, “It looks just like your old Cozmo, dad.” And he’s right. It looks like an updated and slightly thinner (discontinued) Cozmo pump with a color screen.
The menus are on the long side, and some frequently used items are in sub-menus, while lesser-used ones are close to the surface, with no provision for letting the user select where items appear. That said, the overall the navigation isn’t horrible, and the number of “are you sure?” screens—while more prevalent than I personally like—is tolerable.
- Out of the box the pump comes in a practice mode so you can play with buttons before hook up (or even before training).
- CGM alarm thresholds are programmable by time of day.
- Filling of tubing at site change is rapid.
- CGM calibration is crazy slow.
- Sensor changes are also slow, complicated, and require a ridiculous amount of tape that often makes my skin itch.
- In auto mode, the system won’t let me correct mildly elevated numbers, as it is content that I’m “in range.”
Comparing Minimed and Dexcom CGM Sensors
To be honest, my biggest worry about my 670G trial was the MedT Guardian 3 CGM sensor, which I had heard nothing but bad things about. Initially I wore both the MedT and my Dexcom G5, calibrating both with the
Still, like all CGMs, the MedT sensors aren’t immune from doing the funky chicken dance. At 3:49 in the morning, while traveling, the 670G woke me with the news that I was 80 mg/dL and dropping. Seriously? I did a fingerstick and found I was at 184 instead. The pump history showed that the CGM thought I was dropping for over an hour and insulin delivery had been suspended. To add insult to nocturnal injury, the pump refused to accept the new calibration, telling me to wash my hands and wait 15 minutes.
While not perfect, the 670G performed fairly well in these early days of using it.
Rocky Rollout and an Upgrade Controversy
While I’m thrilled to be able to trial-test this product, many in the D-Community are not as excited that they haven’t been able to get their hands on the 670G — especially since they were originally told “spring” would be when that would happen. But in gradually rolling out this new system, Medtronic is moving more slowly than it first indicated and people aren’t getting it as quickly as expected.
Has MedT has bitten off more than they can chew, or are they just being careful with the 670G rollout? The MedT Loop Blog claims “the demand for the product surpassed even our own expectations.” Right now the company is shipping product only to customers in their Priority Access Program — basically folks who got to the head of the line by purchasing the pre-model, 630G.
But even those people may have to wait well into Autumn for their “free” upgrade, a bizarre process that requires patients to pay $299 upfront which, MedT says will be refunded following “a set of activities” which includes returning the old pump (reasonable), filling out surveys (questionable), “sharing your story” (unacceptable), and uploading your data to MedT (outrageous?)—all within 120 days.
The fine print is, “Please know that by completing these activities you give us permission to use the content.”
This upgrade regimen drew heavy flack from analyst David Kliff of Diabetic Investor, who didn’t mince words in condemning the process, stating in his email newsletter, “they are screwing the patient.” He feels the upgrade is a bait-and-switch gimmick engineered to increase MedT’s bottom line, and he accuses the company of knowing that most patients won’t complete all the necessary steps to get the promised refund.
670G in the Field
I had hoped to get my hands on the new BD-developed FlowSmart infusion sets (aka Minimed Pro-Set) to use with the 670G, but that was a no-go after MedT pulled it from the market after a limited initial launch and now they say it’s still being evaluated for prime-time launch.
Turning back to my personal experiences with the system: Once I was able to accept that I was no longer in charge, and just let the pump do its thing, I found that much of the time it actually does as well as, or better, than I do on my own —and with a lot less effort on my part.
The hardest thing for me personally, was not having a quick and easy way to look at my CGM value and trend. In auto mode, the pump only displays a blue shield icon with your latest number, and sometimes a trend arrow if it’s changing rapidly. I’m used to thinking about the level and trend of my sensor info constantly so that I can intervene, but with this pump on point, changing insulin delivery all the time, there’s actually no need for me to fret constantly over my blood sugar.
Strange at first, but I found this to be amazingly liberating once I got my head around it.
Still, I’m not very far into my trial, so the jury’s still out. Will the range tighten up? Will my skin tolerate the many layers of tape needed to hold the CGM transmitter on? Stay tuned for a follow-up report. I have the pump for three months, plenty of time to iron out the wrinkles and see how much it changes, or doesn’t change, my diabetes control.
And my life.