My Experiences using MiniMed 670G Hybrid Closed Loop System

High-level review:

I have been using the 670g since April. It was not love at first bolus for me with this system.  It took more time than I expected to fine tune it which left me feeling pretty frustrated.  I had pretty good diabetes management before starting on the system, with average A1C-s in the low 6.0s and blood glucose levels at 81% in range.

When I started my first insulin pump, I had one basal rate and one carb to insulin ratio.  And it took quite some time for me and my health care team to learn how to adjust everything to get it to a good spot.  Starting on the 670G was kind of like that.  It was frustrating, but, with some time, patience, attention to CareLink data I have come to love it.  

In more Detail

Lows:  

Before the MiniMed 670G hybrid closed-loop system:

Before starting on the 670G system, I typically experienced 2-3x low blood sugar events that required treatment a day. Lows typically happened first thing in the morning, and after exercise, sometimes up to 24 hours after exercise (lag effect).

Since the MiniMed 607G hybrid closed-loop system

Within hours of starting on the 670G, in manual mode, suspend before low kicked in!  I did cancel it the first few times it engaged though, not trusting that my blood sugar wouldn't then skyrocket from not received any insulin.  After a quick check in with my trainer who suggested I trust the system, I did just that.  The next time suspend before low engaged, I let it do its thing, and it worked like a charm.  

Lows still happen, but not as frequently, and not as extreme as before.  I may have one a week where my blood sugar will drop quickly and I'll need to treat with 1 glucose tablet.  

More from Medtronic on Suspend Before Low:

With the Suspend before low feature on the MiniMed 670G system, your pump stops delivering insulin before you go low. Learn more about this feature http://bit.ly/2iluQDv

Exercise

Before the MiniMed 670G hybrid closed-loop system:

I worked with my endocrinologist and diabetes exercise physiologist to come up with a plan around food, insulin, and exercise, specifically Zumba.  We agreed that my target blood glucose level should be close to 150 going into a Zumba class. 

Staring a temporary basal rate an hour before exercise, ending 30 minutes before class ended was the recommendation that they provided me with.  I had varying degrees of success with this plan.  Sometimes my blood sugar would go up, sometimes it would go down. Sometimes it would go up very high very quickly then drop quickly.   Sometimes it worked without issue. 

Since the MiniMed 607G hybrid closed-loop system

I started on the system this past April and couldn't wait to exercise and try the temp target. The temp target is designed to keep sensor glucose value around 150, the same goal my healthcare team gave me as well.   I wasn't convinced it would work, but I followed the recommendations of my health care team and started the temp target an hour before Zumba class, and set it to end 30 minutes before the end of class. It worked!  My starting blood glucose value was 147 (sensor glucose was 149). My blood glucose level just after class ended was 155, with sensor glucose at 152, and did not spike or drop afterward. 

I've now been using the 670G system for  six months and happy to report that my results using the temp target have been consistent.  As with starting anything new, I do recommend consulting with your healthcare team to review how to adjust your diabetes management around exercise.

Highs:

Before the MiniMed 670G hybrid closed-loop system:

High blood sugar for me is anything over 160.  I might not do a correction at this point, but I’d definitely pay attention to how quickly my numbers were climbing at this number.  I’d have 1-3 a day that would require a correction.  The worst was the swings from low to high or vice versa due to exercise (addressed above), but most common from over treating a low.

Since the MiniMed 670G

Highs still happen.  However, the swing from low to high has improved.   My CGM graphs no longer have peaks and valleys of highs and lows, but a nice rolling line. Highs still do happen, but now that means 250, vs 35 since the system adjust the auto basal rate.  There are time when I have to correct, but

Guardian Sensor 3:

I have used Medtronic CGM technology since it first came on the market - SofSensor, then Enlite, and now Guardian Sensor 3.

The SofSensors worked well for me, but I was not a fan of the insertion process so I didn't use them often. I truly loved the Enlite sensors.  From day one they worked really well for me, so when I heard the hype about how much better the Guardian Sensor 3 was, I was skeptical. 
But, they have been better for me than even the Elites. Most of the time my blood glucose value is very close to the Guardian Sensor 3 sensor glucose value - usually within 5%, often less.  The rare time it has been greater has usually been from me calibrating at a less than optimal time (like after exercise).  

Your experience may vary:

You know the saying "your diabetes may vary?"  Your experience with the 670G may vary too. It seems as though some folks start the 670G and are in the 120-range from the start, And for others, like me, it has taken some time to get there.  It took a good 3-4 months for me to "get there" but I really do love it now. 

Feel free to reach out to me if you want to chat on one!
Twitter: @PhyllisKaplan