The Auto Mode experience: 670G two weeks in

Checking back in, here at the end of my second week on auto. Thought it might be interesting to give a more experiential version of what it’s like.

First off, It looks the like a regular pump, but it ain’t. I’m just starting to get my head around that. At the macro level, the biggest difference is that you can’t wing it, the way you can with a regular pump. If you’re used to a lot of hands-on, stick ‘n’ rudder control over what your pump is doing, as I have been, this is a big adjustment. F’rinstance:

Bolusing for meals or corrections.

  • This is a Wizard-only proposition. The system always needs a “why” for whatever you’re doing, in the form of carbs or meter BG or sensor values, so it can adjust itself accordingly, therefore there is NO Manual bolus. You can’t just decide, “Y’know, I think I need an extra unit” for whatever reason and go plug that in. This has been especially difficult these early days where settings aren’t dialed in yet and I’m running higher than I want. It sets its own correction values and you can’t just hit the up arrow to make it give you more. The algorithm has to learn you need more, and what it is allowed to do to get you back on track is limited by your settings. This is especially frustrating at the beginning, because they want the algorithm to do its thing for a while before deciding, ok, you can change one of those settings and see if that does it. Means kind of a long haul getting it dialed in.

Basal doesn’t mean basal

  • This is subtle and a bit elusive to get my head around. Those big square wave basals have been replaced by these little continuous blips, right? And at first you’re inclined to think of that as your basal rate, but on your old pump that was just a continuous increment based on an informed guess about what it’s going to take, meals notwithstanding, to keep you in a certain range. The pump doesn’t have any way to know if you’re in that range. In Auto, though, it does know where you are, and it’s continuously trying to pull you down to, or pause so you float up to, that magic 120. This is a different logic and impinges on a lot of things. Such as…

Sensitivity factor isn’t a factor.

  • This one still perplexes me. You do have a setting for it, but it’s only operative in Manual Mode. In Auto, it doesn’t do anything. Drives me a little crazy because I want to adjust the ratio of how many BG points a unit insulin of insulin brings me down so I can force the thing to give me MUCH bigger corrections than I’m getting now. But instead, they want the algorithm to figure out what it has to do to reach the magic 120 (actually 150, since that’s what it targets when figuring correction boluses, then the microboluses are supposed to get you the rest of the way to 120). Well, ok fine, sez I, but when I do a BG check and I’m at 240, and the pump says “You need a correction!” and I sez “Yes, hit me with a big one!” and it blips out ~1 paltry unit when my experience tells me I need more like 8 - 10, it’s a bit maddening. I’m still trying to get more information on this one but the partial answer I do have is that the Algorithm (oh mighty Algorithm!) just hasn’t learned me yet. Which leads into…

Don’t exercise, just sit there!

  • This is apparently a mistake I made, my first week-plus in Auto: I’ve been exercising down my highs, since the pump isn’t doing it on its own. The problem is that that prevents the pump from learning that IT needs to work harder, so some of the learning I was hoping it would do… it wasn’t doing. Therefore I’ve been deliberately not exercising the last few days, because I want the baseline to reflect what I need when I’m not going for a strenuous walk after lunch every day. Been also holding off biking for the same reason. Not for much longer though, dammit.

Bottom line is that I’m still curious enough to stick with the program and see if I can get out the other side to having the results I’m seeing from some of the more experienced people in the 670 user groups. So hopefully I’ll come back to report things going more the way I’d like next week.

BTW, if interested, my post about my first weeks (auto and pre-auto) is on TuD here:


DrB, let me be the first to thank you for posting this. I had been thinking about these things, but had no idea how much “learning” is required before your system works the way you want it.

If this takes weeks-months to get set-up I can imagine how frustrating that would be.

Also, we stick and rudder all the time, I will have to prepare my son for the adjustment. How long have you heard it taking to adjust to you?


I went into this knowing that my rosy expectations when I first started pumping set me up for a lot of frustration, and I was determined not to have that happen this time. But even with that in mind, there are just a lot of things that are different in ways you can’t anticipate if you haven’t actually started doing it. That’s a big reason I thought it would be good to leave a record of the experience: so others can get more of a sense of it as I’m going through it.

Re stick-and-rudder, I mean, that’s why we’re ON these sites. Much of what I’ve read, posted and learned from TuD (and now FUD as well) has been about the hands-on tweaking and pre-bolusing and under-the-hood hands-on stuff that has my endo referring to me as Mr Flatline. And this is SO different from that. The optimization has to be done at such a remove–you can’t just whack yourself with a big rage bolus when you’ve been stuck too high too long–and familiar terms don’t always mean quite the same thing. AIT (Active Insulin Time) turns out to be a much more important setting than on a regular pump, for instance. It’s a really strong lever for changing how the whole system behaves. And the “microbolus” versus “basal” distinction is subtle but also really critical. Big shift from MDI to a standard pump is that business that the pump is continuously dosing you, so you have to be cautious about changing those increments because small changes build up. The microbolus thing is similar, except the doses aren’t consistent, they’re being continuously altered subject to multiple variables, so even more caution and head scratching is involved.

My sense is that the people who are happiest with it are the ones who have been doing it for half a year or more, though things do start to settle down well before that. When I think back on it, I don’t think I was completely satisfied with my original pump until about that far along either. But it does seem like this is a bigger mental shift. The logic of a standard pump isn’t really as different from MDI as this seems from a standard pump. The other thing I remember about my original pump experience is that I really only started being happy with it when I felt like it was time to cut loose from my trainers and start adjusting settings and things myself. I think that’s also parallel here. The ones who are most satisfied also seem to be the ones who are comfortable with tweaking their AITs and also doing less orthodox things like taking it out of Auto overnight to get better Dawn Phenomenon results and that kind of thing. I don’t want to do anything like that until I’ve pushed it as far as I can to learn things on its own, but as with all these technologies, we who have to live with them 525,600 minutes a year eventually find ways to make them work for us rather than the other way around.


I hope that by the time Tandem get’s theirs on the market there is a way to shorten the learning cycle for the pump. I don’t know that we could go half a year waiting for things to settle down. Of course, having a pump keep you close to flat without any input other than meal entry would be a tremendous accomplishment. I can’t wait to hear how much less attention you have to pay to your pump to still get great outcomes.

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We don’t really know how any of the other companies will setup their algorithm. They may do it in a completely different way that doesn’t have the same learning process.

I certainly hope other companies offer something other than the 120 or 150 targets…


Well, I that’s more bleak than the impression I meant to give. I think it’s more the thing that with any complex process, getting to 70% is relatively easy, 80% not quite so, and that last 10% to really get it humming takes almost as long as the rest put together. I do read a lot of reports from people saying they haven’t got it where they want it yet but feel like they are getting there. I think the hardest part is the first two-three weeks, when you’re having all these problems and not seeing much progress. That’s where I am now.

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Agreed, although as DrB points out, we may not understand the complexity of that target, so it may turn out to be fine.

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I am not sure you gave a bleak impression, but your impression painted with a little frustration is “real” as they say, and I for one appreciate the honest assessment.


@drbbennett, what an OUTSTANDING review and Q&As!

This was the best feedback I have read on the 670G: analytical, thoughtful, deeply understanding of the underlying process.

Thank you! I so look forward to your next stage review!


Thank you!! I am very interested in your experience with the 670G and will look forward to any updates you can provide here.

To start with, I wonder if your algorithm adjustment would have been easier and shorter if your Endo (or you?) had chosen different parameters? In other words, maybe your Endo was being overly conservative, as they often are when changing a patient from one insulin or pump to another (using 2/3 previous known good dose, lower insulin correction factor, etc.) Do you know what kind of initialization it required and whether changing those would start the algorithm in a different place (TDD, basal rates, ??)

Secondly, its discouraging to hear about the effect of exercise. Is there no way to alert the pump to the fact that you are starting to exercise, and thus it may need to adjust its algorithm? That seems like it could be a serious problem even once the algorithm has adjusted to your needs - especially around here where there are lots of us who exercise regularly.

Thirdly, I am really confused by the sensitivity factor being operational only in Manual mode. Are you sure that it doesn’t at least use that as a starting point for corrections - this seems so wrong that I would consider it a bug in the algorithm.

Finally, I would be sorely disappointed if I couldn’t use it on Auto overnight - I believe this is the place where an auto adjusting pump should do its best - and its also the time when you’re most vulnerable because of being asleep.


@drbbennett Thank you so much for the ongoing review of this cutting edge technology.

I think that for many of us it would be a no go simply because it would be next to impossible to give up control of our…control.

For some reason I have never been interested in a pump at all. I think not even wanting an Omnipod demonstrated to me that the objection wasn’t even the tubes and big contraption. I think the real reason is ultimately giving up even a little bit of control over howI manage my numbers.


I want to also say thanks for the detailed review and information. It’s very interesting.


@drbbennett, are you in contact with the medtronic trainer, like we are with the Omnipod trainer?

if so, are you able to get get info from him/her? Does he/she have feedback on how long it will take you to lock on a good algorithm? Will sports always be an exception that you cannot deal with?

To clarify for sports: is it possible to suspend or decrease the “basal” for period of time? I guess you could always switch to “manual.”

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This is a big issue for me. Currently I’m on a bike/walking hiatus to force the issue of making it work as it’s supposed without any outside assistance. But yes, the built-in solution is to set it to the alternative BG target of 150. This is part of the different logic: you can’t just tell it “Give me 50% of my programmed basal” as with Temp Basal on a standard pump, because there is no programmed basal. There’s only the target. Obviously many people have been expressing dismay about the fixed 120 target, and that’s a separate issue. But the 150 is specifically designed for exercise. I understand it as a way to keep from going low, rather than that you’re actually going to end up at 150. Dunno how it works out in practice because a) I’ve been running high anyway, and b) before I went on my hiatus I kept forgetting about trying it.

And yes, “suspend” remains an option in Auto. They recommend that you do suspend before morning shower and the like so it doesn’t get confused thinking it’s given you microboluses you haven’t actually had. I’d stopped doing that on my old pump because of how often I’d get to work before realizing I’d never turned the darn thing back on again.


Yes, that’s what I wanted to convey. I was expecting some frustration at this stage, and guess what: yup. But I’m determined to keep to the terms of the experiment so I can really find out if it does what it claims to do.

  1. Yes, and she’s great, 2) yes, but there are limits. Today I asked whether the change in ICR just applies to the Bolus Wizard or to the algorithm as a whole. My friends on the FB user group said she probably couldn’t/wouldn’t answer because Holy Algorithm keeps Its deeper mysteries unto Itself. It’s kind of like how those of us in the Web world are always trying to infer the arcane ways of the Google ranking system, the One Ring that rules us all and over which we have no power and can only speculate.

I am really cheering for you, @drbbennett. It would be great if this pump could be used to fulfill the needs of those of us who are trying hard to do the best we can do. It is clear that it represents an extraordinary step forward for the average Joe. If it can be the same to the self-demanding PWD it will be a milestone. So I am cheering for your success!

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That’s the real test for me. There have been a few hints around the margins to the effect that maybe it’s really more for people who aren’t achieving ~6.0 A1Cs already. My DBE: Of course you realize your numbers before you even started were pretty amazing, and in spite of the problems you’re having with it, your in-range time is much better than most people get who aren’t on it. Well, ok fine. But 120 = a 5.8 A1C, which would be better than I’ve ever done, so let’s see if it can really do that. If it doesn’t end up improving on what I can do on my own, I can always go back to Manual


@drbbennett, this would be a real problem for me, because I am in sports practices almost every day. I hope it figures out your patterns quickly. I had to stop 2 weeks while I am starting on Omnipod but it is hard to do that.

I see a problem though. The pump will never know that you are in the middle of exercising. The reason I am switching to a pump right now is that I need to change my basal hard before, during and after sports. If I have a 90 minute practice, I need to change my basal 2 hours before (lower), then during,. then probably one or two hours after, or maybe a lot longer (because I get low after exercises, even though i replenish right afterwards. That’s a lot of hours every day when I need to do something just for sports.

How will I be able to do this in Auto mode?

I read what you wrote about switching to the 150 goal. But that won’t really do all I want to do.

That would get me angry. I am sure your in-range time is better because you work harder at it. The pump should make you better than you are. Your DBE should know this is the wrong thing to say.

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Seems like it would be difficult. Of course you always have the option of switching over to manual mode periodically, but if you’re doing that for a large percentage of the day it might not be worth the effort of training the thing in auto.

We have a great patient-caregiver relationship so I didn’t find it upsetting–he and my endo both know I do work hard at it! But you’re right, at this stage it feels like a lot of work for something that currently is not doing nearly as good a job as I was doing before. I had that same experience when I switched to a pump originally, though–it took a couple of months before I really felt like I was surpassing where I’d been before I started. So for now I’m gritting my teeth and giving it my best shot.