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Medtronic MiniMed 630G insulin pumpPoint/Counterpoint: IDS Clinicians Offer Different Perspectives on the Medtronic 670G

Several months ago, Gary posted his thoughts after trying out the Medtronic 670G hybrid closed loop system.

Since then, two other IDS clinicians have given the system a try:

jennifer smith

Jennifer Smith RD/LD/CDE

alicia downs

Alicia Downs RN/MSN/CDE

Both have extensive experience using a variety of insulin pumps and CGM devices.

After several months of using the 670G in “auto-mode,” in which the pump self-adjusts basal insulin delivery based on input from Medtronic’s Guardian continuous glucose monitor, here’s what they had to say.

Q: What were your needs/expectations going into using 670G?


I was optimistic about trying the 670G. I wanted it to make life with diabetes easier as well as safer all around. Given it is the only FDA approved hybrid loop system on the market, it opens the doors for this type of technology to get approved from other pump companies as well. This is very exciting since we all need a “partner” so to speak in our self-management. Up to this point, all the pumps on the market have had smart features, but the PWD is the one who has to make use of the smart features by using their own brain to enable them.  With the variables we each have in our day to day lives, this means constant interaction if we really want to avoid a roller coaster.

Having type 1 for almost 30 years now, I’ve managed to figure out adjustments to many of the variables that affect my management.  But, I would really like a product that has my back – a partner in this 24/7 of management. Essentially, one that can fill in the gaps between the times that I’m not looking at my CGM screen or checking my BG. With 2 kids now (5 years old and 14 months old), that tends to be less often the “looking and evaluating for making changes now”, and more the “oh, I think I see a pattern here, but I’ll have to make an adjustment when my son doesn’t have glue all over the kitchen table, etc”. Anyone with a busy life, regardless of bambinos can understand the desire to have a system that not only tells you that BG is dropping or rising, but offsets that trend right away.  That is what I expect(ed) from a system like 670G.  I’d like a partner that sees what I don’t and doesn’t ask me to make an adjustment, it just does it based on a fancy algorithm that some wonderful mathematician figured out!


My expectations were pretty low. I was honestly expecting that the system would not keep up with my habits and my widely varied basal needs. My control on “Alicia mode” is where I want it to be, so I was going in a bit skeptical.

Did you find the system easy to learn?


3 user manuals – one for the pump, one for the CGM and one to learn how to use the Automode feature of the system.  Lots of reading, but pretty easy to get set up and learn how to use if you have used an insulin pump before.  There are a lot of menus to look through on the pump itself for using the sensor and the Automode feature and to customize them, and I feel navigating these took longer to actually get used to than the actual set up of the pump/sensor.


I found the principles of the system easy for me, but diabetes is my job and I’ve been pumping close to a decade. I found manuvering the menus of the system a real headache. To this day I keep a flow chart of all the menus taped to my computer monitor because navigating where things are is a headache. I also found it hard because, for me, diabetes is about learning to see things coming before they happen. Anticipation makes life move more smoothly. But as much as I learned about the system I was never able to learn to anticipate its demands.

Once you began using AutoMode, how did your life change?


I’d love to say that using Automode changed my life for the better – honestly, I would.  However, for me, it actually made things more annoying and variable. I believe a major part of this is the fact that the Guardian Sensor was just not as accurate for me as the Dexcom that I’ve come to use and love in the past 7 years (prior to that I used the Abbott Freestyle Navigator, which was fantastic and I still miss it!). The Guardian sensor was accurate most often for me when I was literally sitting and not doing much – so office work time seemed to stay pretty on target with my fingersticks and with Dexcom (especially if I wasn’t eating anything). However, I’m not a sedentary person and I eat food!

** A side note here in that when I was in Manual mode using the Guardian CGM, it was more accurate for me than when I was in Automode. It seemed like all the request for confirmation of BG and calibrations in Automode made it less accurate and more variable.

I love exercise and with 2 little boys who are busy, I’m not sitting very much after I’m done with work. This is where things would get very off with the sensor. It lagged in noting a drop in my BG as well as a rise in my BG compared to my Dexcom – especially during exercise and after meals. I also found that overnight, while it kept things stable, I’d wake to find my straight line was not an accurate value – hovering at 122 all night via Medtronic would have been fine, but when I tested upon waking and found a fingerstick of 196 instead and then looked at my Dexcom (I turned alarms off on my Dexcom so as to not get so many notifications overnight) I saw I had a rise in my BG and then stabilized at 170-195 all night – bah!! Not where I want to start my morning.

The other parts of not loving the system are the alarms and requests for blood. Seriously, a nice flat line overnight should mean a system isn’t asking for more information to confirm it is doing what it is supposed to do. If I calibrate before bedtime that should suffice in my mind. It is great to have a nice flat line overnight – which should mean I sleep all night without waking up for alarms.  Argh – I got alerts overnight for false low BG, then the system would tell me to add a BG to stay in Automode, or to calibrate again, etc, etc and on and on. The things it asked for and the alarms made me a bit crazy about where my BG was at any point in time.  I had more roller coaster in BG as well as more low BG (and false low BG) then I had when I was doing all of this with my own mental power and self-adjustment on my own pump.


My first few days on auto mode were VERY frustrating as the post meal curve I have come to anticipate for years changed. I was going higher than I had anticipated later after meals. In my pre670 world that typically spells disaster! It means I’m going to be bolusing to bring blood sugars down for hours, so I was really upset to see that. I spent a number of afternoons and evenings griping to my husband and showing him sensor graphs that he pretended to care about.

But I forced myself to do what Medtronic tells patients and “Trust the system” And over the course of the week the numbers spoke. I was spending the same, if not a little bit more time in range over all, that time had just shifted from what I was used to seeing. And my average had remained the same. So I let it do its thing. I even pushed it into what I thought would break the system, a steak house dinner, and a trip to Disney World! But it handled both without kicking me out of automode! I was impressed. But I still had this constant nagging feeling of not knowing what was going on with my management. meal timing was off, reactions to exercise were off, the predictability I’d come to wrap up in like a blanket was gone, and it made me more tentative in my day to day living.


Is there anything you wish Medtronic did differently in designing this system?


A) The system needs to allow the target BG to be adjusted based on user preference. Honestly, I target a BG lower than the 120 preset value in this pump and my corrections target a lower BG than this system targets too. The current targets restrict use of this pump to those who are NOT considering pregnancy or are NOT pregnant, as the current default target is too high for pregnancy management.  This is a fair percent of the population of women with type 1 diabetes.

B) The alarms, alerts and requests for information need to be changed. I know it is built in as a safety feature of checks and balances to ensure the system is working, but this was a big part of why it was annoying to me.

C) Allow the system to work with known advanced features on current pumps like extended bolus, temporary basal, and the ability to adjust the pump’s recommended bolus based on the need of the PWD (ie – if you know you are going for a run in an hour and you are eating/bolusing now, you should be able to adjust the suggested bolus down to avoid having so much IOB for the run –without having to exit Automode to adjust!)

D) Better menu system – there are too many steps and too many screens to look through to find what is needed quickly (or at 2am when it is requesting you do something to stay in Automode).

E) Better sensor accuracy with less interaction needed by the user to keep it accurate.


MENUS! Wow my thumbs were aching from that pump! Things that you interact with 5 times a day are buried 4 menus deep, and features I don’t think I ever used are right on the home screen! The buttons themselves are even tough to push and awkwardly placed. Nothing about the menu set up is in the least way intuitive. In a time where any 3 year old can pick up most any technology and maneuver the interface without any instruction; these menus feel like something out of the DOS prompt era of menus listed under sub menus that only make sense to the engineers who built them. (And were often the source of an inside joke rather than any kind of user driven logic) I found myself wondering if Medtronic ever put this system through any kind of user focus group during the design phase, because it sure doesn’t feel like it.
I also really wish they’d given me a way to temp basal for things that I know are coming rather than waiting for the fall out. I know I’m going to work out, so let me use what I know!! I’ve kept myself alive quite well for quite some time with my knowledge and skills. Eliminating them is tantamount to taking a bicycle away from a child because it is dangerous to ride in busy traffic. But i’m not a child, I’m a professional cyclist, let me use what I know to get where I want to be more effectively!! Let me keep the anticipatory skills that serve me so well rather than forcing me to be reactive, as if I had no idea a workout was coming. I never did get the chance to put this system through my personal workout challenge, summer heat! Advance temp basal and bolus adjustments literally save my life all summer long. The idea of going without those features through a Maryland summer is daunting at best, and may spur me to give the system a more high stakes trial in a few more months.


Do you plan to continue using 670?  Why or why not?


I do not plan to continue wearing the system. For me it brought variables to my management and made me wary of where my BG was headed. I did not like to have to respond to so many requests through the day (and I’m one who tests via finger-stick a lot already even though I wear a CGM 24/7) and I felt like I had to keep wearing my Dexcom to stay on top of where 670 was saying I was.

I prefer lower targets than the system allows and my need to use features like extended bolus or temporary adjustments for exercise are not met by the Automode system.

In full disclosure I had been using a LOOP insulin pump prior to starting use of the 670G and I feel that the 670 was a step back from what the LOOP system was doing for me and my management.


The system did its job, but it’s not for me. My average and in-range time showed a statistically insignificant improvement over “Alicia mode” but took a LOT more effort to get there. “Alicia mode” does not wake me up at night to enter blood sugars, it does not require me to lie to the system to safely workout, or to get the corrections I want. I’m not an early adopter by nature. I don’t do an update on my phone until I notice performance issues from the outdated system, and I will drive a car until it costs more to repair it than to purchase another. I only update pumps every 4 years because my insurance will cover it and I want to get my money’s worth! I think that the next couple of years is going to bring us some great options in hybrid closed loop systems from other pump developers, so I will wait to see what they bring to the table before wading into the HCL life full time.

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