Issues with the 670G “Looping”


I am 3 weeks in with my 670G and have constant issues with Auto-Mode looping. I think I’ve only gotten Auto-Mode to work for a couple of days the whole time. I’ve tried everything mentioned here, waiting (30 min to 2 hrs) and the second slightly off BG entry. Neither have worked for me. I’ve also tried turning off Auto-Mode on the pump for a while, then turning it back on with a new BG. I’m not sure what else to try. Auto-Mode seemed to work okay when I had it working, but this whole loop thing is infuriating.

Maybe I’m having such trouble with the loop because my sensors are almost always 30-40 pts or more off of my finger stick BG. Seriously, I can count on one hand the number of times my finger stick and sensor readings were within 10 points of each other. This is also pretty maddening, especially at night when the sensor THINKS I’ve gone low and says I’m at 45 setting off alarms (even the vibrate wakes me), but really I’m at 90. I read another comment here saying that you shouldn’t calibrate if your finger stick is more than 35 points off of the current sensor reading. If that’s true then I should probably never calibrate. But isn’t that the entire point of calibrating so that the sensor knows where it should be and can correct if it’s off? Most of the time right after a calibration is complete (assuming it’s accepted) the BG displayed immediately starts out 20 pts lower than what I entered and just goes off from there. This seems to be my norm whether the sensor is on day 1 or day 6.

I also have yet to put on a sensor that didn’t fail within a day. After the second one I looked online to see if there was a way to recover a “failed” sensor. If you detach the transmitter from the sensor, put the transmitter on the charger for a bit (15-60 min usually does it), then put it back on the transmitter and start a new sensor from the pump it usually takes it again. Have to wait for the 2 hour warm-up to complete. Maybe all the sensors I’ve used so far are from a bad batch? Whatever the case, I’m quickly losing faith with the Guardian 3 sensor’s ability to accurately show my current BG level. In my humble opinion, it being 30+ points off from a finger stick is not accurate. That difference can easily be the difference between needing to treat a low and being perfectly fine. Back when I was using my Dexcom G4 Platinum I don’t recall it being so wildly off so often. Also, the way the Guardian 3 attaches, which oval tape or something other adhesive tape, getting the transmitter sticky, and requiring regular scrubbing is miles behind the simple snap-in of the G4. Medtronic couldn’t have come up with a better solution?

So far I’ve only put the sensors in the recommended areas around the stomach, but each one has been a similar story. It doesn’t seem like rocket science, I’ve read the manual on this many times, talked with support and trainer, but no one seems to have an answer. Does anyone here have any additional tips or suggestions? I’d love to really give auto-mode a try and see if it does really work long-term, but so far that just hasn’t worked for me. I stopped with the Dexcom because I really don’t like having two things hanging off me at all times, and the Guardian 3 isn’t doing itself any favors so far. I’m really thinking about asking if I can return the whole thing, get a refund and go with Omnipod.

(Paul Burger) #22

Hi AWG0681

I really feel your frustration, and you hit on so many of the frustrations that I too have with the 670G, and with the support you get/don’t get from Medtronic.

Your experience so far has definitely been worse than mine, and not sure there is anything I can say to help.

I will re-iterate that when the device is working, it really does work well. When you can get it to finally go into Auto mode, and stay there, it really does keep your BG much more controlled, and I have many fewer alarms that ever before on my old Dexcom/Animas units.

Day one of every sensor insertion is a challenge. Like I said above - if I try to not allow myself to get too frustrated and just take a deep breath and let the pump settle itself down for a while, this usually does the trick. I have, however, gone 24 full hours before I can get the thing to go into Auto mode. If you keep entering BG and Calibrations back to back, however, that is when you get the sensor failure. Just let it rest a bit (2 hours) and try again.

Totally frustrating, I know, and this is not how an FDA appproved medical device should work. I am just giving my experiences and workarounds on how I am dealing with it.

If you do not want to continue on with it, ask for a refund. Not sure what they will do, but you can certainly give it a try.


(Tawnya) #23

I too have been having a problem with the sensor calibration loop. After having to test 12 times in 2 hours after starting a new sensor, I spoke with a representative from medtronic at length and was given some helpful information.

  1. The looping is a know issue with the pump auto mode, not the sensor. Expect some type of notification from medtronic with a software update in the future.
  2. Do not enter a bg more than once an hour. If it asks for a new bg, just ignore the request.
  3. If, after the rest period, the pump still does not enter auto mode, turn off auto mode and let rest for 6 hours. This should allow the pump to enter auto mode without issue.
    I’m currently doing the 6 hour wait and I’ll update if this is a fix. I really wish Medtronic had notified their customers as soon as they were aware of the issue. I feel like there should be some sort of reimbursement for the extra test strips I’ve gone through over the last few months.

(Ryan) #24

I highly recommend trying a new site location. I had the same problems with inaccuracy and looping with the sensor on my stomach. The thigh works better for me, and other have found success on the arm.

I also empathize with the calibration confusion. It doesn’t calibrate like the Dexcom. I suspect that the system errs on the side of caution. That is, the sensor reading after a calibration tends to side with the lower of the prior sensor glucose or meter reading.

Example: if your sensor says 100, and your meter says 125, the next sensor reading after the calibration will probably be between 95 and 110 (depending on whether you are trending up or down). Sometimes, the sensor will get towards that 125 reading in 15-30 minutes after a calibration.

(Tawnya) #25

Doesn’t seem like a site issue in my case. I’ve used the same thigh several times and it is usually my most accurate site. My sensor readings had been within 5 points of my fingerstick every time during my last looping episode, so it’s not necessarily a conflict with the sensor readings. I did the 6 hour rest period out of auto mode and had no issues when I turned auto mode back on, even with a significant difference between sensor reading and fingerstick. I’m going with the Medtronic representative that it’s a software issue keeping the pump from going into auto mode, not the sensor.

(Linda) #26

That stinks that you are having so much trouble!!! Let me see if I can help.

I have been on the 670 for almost a year now and it now works perfectly all the time. I almost forget at times that I’m a diabetic. At least until I forget to bolus for a meal and then get an alarm for high sugars…oops! :smiley:

All fun aside. First off it does take Auto Mode a little bit of time (month or so) to figure you out. At the start I too was constantly being woken thru the night. At first, I got up and checked and sometimes calibrated and went back to bed. After I while, I went by how I was feeling and either checked or slept thru it. I have not been woken up in the night in a very long time.

Next. Yes you are right, the sensor and BG should not be far apart. Mine are now always very close. Some rules I abide by when calibrating: I make sure to calibrate first thing in the morning, before coffee or anything. I calibrate again mid day, making sure that I have not just eaten anything that might have a big influence on my BG’s. Then one last time either before dinner or before bed. I never calibrate if BG is high!!! I will bolus, wait a couple of hours and try again. I will calibrate only if BG is between 90 and 150. Calibrating at either end of the spectrum will confuse things. I have not had any looping issues in a very long time either.

Oh and the tape…here is what I do. I insert the sensor, put on the first oval tape. Cut second one in half and place it on the other end that is not yet secured. Leave the flap free to secure the transmitter and put this second piece under where the transmitter will go. This makes it all a bit more secure without gungking up the transmitter. Also leaves the transmitter free to be removed and reattached if necessary.

I hope some of this helps and please let me know if you have any more questions that I may be able to help with.

(Tawnya) #27

For anyone still having trouble with the “looping” issue. Today I tried something that was recommended to me by medtronic. Before doing my sensor change, I went into options>smart guard>auto mode and turned auto mode off. After the warm up period I calibrated and my bg was immediately accepted. I waited half an hour then switched auto mode back on. I got the “wait to enter bg” message, and once I entered my bg I didn’t calibrate. Auto mode switched on immediately with no issues! Huge game changer! Now what to do with the rest of my day I had cleared for sensor change?

(Ryan) #28

Good to hear, Tawnya!

Since my experience with the sensors is different (totally inaccurate for the first day), I wait at least 24 hours after starting a sensor to go into auto mode. I wish the user interface explicitly stated times when a BG without calibration is best.

(Arnold) #29

The biggest flaw in the 670G (which never got fixed from the 500 series) is the lack of “situation awareness”. In simple terms, the 670G blindly demands and takes actions because it can’t recognize what is happening around itself. The almost universal “looping” problem has its roots in the pump not being able to recognize its current situation. Case in point, the pump will repeatedly demand that a “BG” be entered. Even if one does this, the pump will still think it never happened and proceed to shut down because its continuing demands can never be met. If you look at the “Daily History” screen, however, you will plainly see that the pump did indeed receive a valid BG(s), but it can’t recognize that what it asked for was already done. This is defective software coding, plain and simple. How is it that an ordinary car can recognize that its gas tank has been filled and cancel a “low fuel” alarm, yet a pump can’t recognize that a BG request was already fulfilled? Apparently one part of the pump doesn’t talk to the other part.
The lack of situation awareness further manifests itself when the pump is actually in the middle of a calibration process, yet this very process is interrupted and cancelled as the pump demands that the process that it just cancelled (“calibrate now”) be done! Similarly, a user can be in the middle of actually starting a needed bolus when the pump will actually DISRUPT AND CANCEL the bolus to tell you that you need to bolus.
I have just given you a sampling of the flaws with the 670G. There are many others equally as serious, but this just begs the question, how could the FDA not thoroughly test, yet approve a pump with so many software flaws, and how could they allow the sale of these to continue without a mandatory recall action?

(Jason) #30

Agreed, after looping (again) myself, and restraining myself from throwing this pump against the wall or off a cliff, I did not calibrate the sensor, just added the BG and it went right into Auto Mode. Admittedly, I did not read all 6-ish manuals that came with the pump as I have been using the 630G (and 530G), so I went straight for the “Getting Started with Auto Mode” manual. It would have helped if there was something in there about this known issue - and when I called Medtronic, I got a tongue lashing from the tech service rep as I had not gone to training yet. My pump showed up 3 days before my sensors, I thought it would be a good idea to program the settings, add the transmitter as a device, get familiar with it, that way when the sensors came in all I had to do was put one in, swap the reservoir from my old my old pump and I was up and running. I had called tech service because it hit midnight the day I started using the pump, I was in the loop from midnight to 1:17 AM (woke me 5 times) during auto mode warn up (genius programming, why not 9:00 am?) and Auto Mode started 6 hours later, rather than the 48 hours that the manual says is would be. Apparently, you cannot turn the pump on, program settings, and leave it in the rewound state as it will start learning – what I don’t know, it wasn’t delivering basal, there was no sensor attached, but according to the rep it was still learning – something, which was part of the 48 hour warm up. I had to ask her to calm down and remind her that I was the customer.

I had been transitioned to the 630G a few months ago from the 530G (and previously I had an Animas pump - which by the way, had the best user interface, best customer service and was the easiest pump to use - RIP Animas) hoping this would be a better experience. The amount of alarms (with all alerts turned off), prompts, etc. in the 630G made me really consider whether I wanted to go down the path of the 670G as they are beyond frustrating. I did go 670 based on the recommendation of my Endo (who is not a diabetic and has “worn” the pump).

I am a software developer (and yes, there are definitely bugs in the software, as there have been since the 530G in my opinion), Medtronic needs to get on the ball as it seems they have no diabetics on the team that develops and tests their pumps. They don’t understand the frustrations of multiple alarms (within 2 minutes of each other, sometimes one right after the other), the lack of being able to use muscle memory to silence an alarm (depending on the alarm, there are multiple button press procedures to shut it off) and it’s not easy to figure out which button you are pressing without looking at the pump – and I have all the feeling in my fingertips, I’m sure there are some people who don’t. Also, from a technology guy, (future request here) touch screens are not a direction to go for these devices, if someone wants a touch screen, extend the display to their phone.

We are all people that work, and lead lives. These pumps are extensions of our body, but the programming and interface makes it hard for them to blend in for us. Ever had an alarm go off while driving, in a meeting, doing something important that you cannot take your attention away from? It’s not always easy to deal with, and it should be. Pumps should also be getting smaller, and for some reason, this one got bigger.

Its unfortunate that Medtronic is the only game in town for a closed loop system, I really wish Animas has come out with something, undoubtedly, that’s where I’d be.

(joe) #31

@jwagner602 @arnoldchase

with animas throwing in the towel, giving up and calling it quits: - you can wait on tslim or omnipod now.

I don’t think it’s a bug at all. I think that it’s a fail-safe based on the sensor’s current raw reading ISIG, versus the new data you are putting in, or trying to put in. If the sensor input can’t be resolved… the thing just asks for another reading. What it is really doing is preventing auto mode and all predictive alerts, until the ISIG versus calibration error is corrected. again, Once there is a big enough difference, it will refuse the new data. and sit there. That (in my opinion) isn’t a bug, that’s medtronic trying to not kill you.

there are ways of resolving isig and current glucose, but if you are going to read isig and then make the next calibration based on that (falsify the calibration data) you will clear the error but you may end up with inaccurate SG. I won’t say how to do that because it’s risky.

the FDA doesn’t test anything. The FDA reviews manufacturers tests and clinical studies. The FDA will inspect manufacturers to verify that their procedures, facilities, and controls are adequate.and that manufacturers are complying with the cGMP (current good manufacturing practice) as it applies under the CFR (code of federal regulations).

better luck to you both. hoping for a real CGM someday and not another interstitial fluid analog.


Well it’s been another month and I’ve kept with the 670G. Thank you to those here who replied and offered suggestions. My overall, summary description of the 670G closed-loop experience is “FREAKING ANNOYING!”.

I did get Auto-Mode to start working, and it does okay. The sensor, in my (admittedly limited) experience and opinion, are very hit or miss. Even after a couple of days of wear I still get readings from my sensor that are 30-40 points off. Sometimes calibrating helps, sometimes it doesn’t. The whole “Wait until the sensor readings are closer to your finger stick” logic and suggestions are completely backwards. I’m not saying it doesn’t work, but the device should be able to accept a new reading, re-calibrate to an acceptable level, and just keep going without having to wait for it to realize I’m not actually at 45 mg/dl and I never was at 45 mg/dl. I’m at 90 mg/dl after briefly dropping to 60. However, 30 or more minutes and multiple very annoying alarms later, it still thinks I’m in the 40s. We really should be able to enter a new BG and calibrate without the fear of causing this dreaded Auto-Mode loop or possibly dropping out of Auto-Mode.

Even when things are going well, it’s still annoying. There are times when the sensor says I’m at 95 or what not and that’s within an acceptable margin from my finger stick. I’m humming along doing my thing thinking all is good, when the 670G complains that it’s been a minimum delivery for 2.5 hrs and wants a new BG or just says New BG required to stay in Auto-Mode. Give a new BG, an hour or two later same thing all over again. I thought I was a frequent tester before, but I test more when I’m in Auto-Mode and using a CGM than I’ve ever had to before just to keep the pump happy. Let that sink in, I’m wearing a CGM, which is supposed to make things easier/better, but it wants readings every hour or two when my BG is well within an acceptable level. This is likely due to the fact that Auto-Mode targets 120 mg/dl and that cannot be adjusted at all (another annoyance), so when I’m in the 90s and it’s giving me little to no insulin it doesn’t know how to handle it. It can’t just sit there and go “User is in an acceptable BG range, last calibration was within the required time, all is well”.

When not using auto-mode and/or a sensor it works perfectly fine as a “normal” pump and that’s really where I’m leaning towards going with it. The constant interruptions in Auto-Mode are a hassle, if I can woefully understate things. I understand it’s all there so the pump doesn’t kill me, but a little more common sense in the user-friendliness of the thing would be good. To anyone thinking of getting a 670G my warning/advice would be “Be prepared to be nagged worse than a parent nagging a child to clean their room. Far, far worse.”

I’m glad this is not the across-the-board experience of everyone using the 670G and that it “just works” for a lot people. However, looking on forums the stories similar to what I describe aren’t exactly few and far between either. It’s a true love-hate relationship with this thing.

I’ll be getting a Freestyle Libre in the next couple days. If that proves to be as accurate as my finger sticks then perhaps life with the 670G Auto-Mode will be a bit more tolerable. If I don’t have to poke myself nearly as much to keep the 670G happy then I’ll certainly be happier.


Also, in case others have issues with wildly inaccurate sensors, I’ve gotten the best results from the sensors using them on the back of my arm. I know it’s not the approved or recommended area, but it works much better for me than on the mid-section as shown in their manuals. Just about every sensor I’ve used on my stomach (regardless of where on my stomach or sides) asks to be replaced 1 or 2 days in and/or is constantly inaccurate with its readings. So, if you have the same issue, try it on your arm!

However, with my Libre coming soon and it saying it is ONLY approved for the back of the arm things may get a little crowded and I’ll need to give them a rest at some point.

(Ryan) #34

My experiences are very similar to yours, awg0681. Hang in there. Like you, stomach sensor sites just don’t work for me. Automode has been slightly more tolerable with sensors on my legs.


Where on your leg do you put the sensor?

(Ryan) #36

On the front of the thigh, about 4-6 inches above the knee.

(Jess) #37

I transitioned from the 630G system to the 670G system and have been using it for about a month now. With my old 630G, I was using really cheap test strips ($2 per box) that my insurance mostly paid for. I was having a lot of trouble with CGM inaccuracy. Turns out, it was the cheap test strips I was using. The repeatability of the Kroger brand test strips was pretty awful, and this was causing inaccurate calibrations. After 6 hours, the disagreement between the sensor and my next blood-sugar measurement could be as much as 40% (That’s percent, not mg/dL). I did a little experiment over 3 days where I tested my BG twice with 3 different meters (6 times), about 4 times a day. The repeatability of the Cheap test strips was about 2.5 times worse than the repeatability of the Contour Next test strips. After this, I switched over to using the more expensive Contour Next meter and test strips, and most of my calibration and sensor error problems went away. I thought about averaging the results from multiple cheap test strips, but It would require 6 consecutive tests be averaged to get the same kind of repeatability I was seeing from the Contour Next meter. I decided to just switch over the Contour Next meter, as averaging 6 BG tests every time I used the cheap meter seemed a little on the crazy side.

The takeaway - If you’re having CGM accuracy/calibration problems, make sure you are using the Contour Next meter that came with the pump.


My insurance won’t cover the Contour Next strips, however I did buy some out of pocket. The other meter I use is a One Touch Ultra with the One Touch Ultra Blue test strips. I consider both of those meters to be good and fairly reliable. When I’ve got a “bad” sensor it didn’t matter which meter or strips I was using, the variation was always far off between BG and SG. I have also had issue with cheap strips and meters though, especially when BG levels were far outside normal ranges. That could definitely come into play, but don’t think it was the issue in my situation.

The number of bad vs good sensors for me has been more bad than good. As I said in an earlier post, even when the sensor is doing what I’d expect the pump is still very needy. I may be in the wrong or minority thinking this way, but in my opinion, something like the 670G Auto-Mode should make life easier and let you think about T1D less; not more as has been my experience. Again, I realize it works well for a lot of people and people are more likely to be vocal if things aren’t working than when they are going fine. Perhaps those of us with problems are the more vocal minority. Things have actually gotten better overall since I first posted, but the 670G is still much more work and mental load than my previous pump and I’m yet to be convinced it’s helping me that much more than any “regular” pump. Maybe it’s just my bad first impression that’s coloring my opinion.

(rpe37stang) #39

@awg0681 My insurance does not cover the Contour Next test strips either, but I had my doctor say that they were a medical necessity for this pump and my insurance has been covering them anyways for 5 years. I would recommend trying something like that. Using the meter that is meant to go with the pump makes a huge difference!

Also most insulin pumps are released in Europe first. We generally get the equivalent pump a year or more later. When this happens a lot of the bugs are worked out in Europe. The US was the first to get the 670g so we get to work out the bugs in the pump this time. With getting things first come some inherent issues. I have been on the 670g for over 8 months and it took some time to get used to the differences in it. I would say that it is by far the best pump I have ever used and the most accurate.

(Vickie) #40

I have been having issues with my stomach so I put the sensor in my thigh. It seems to work. But I feel like with all sites sometimes its a hit or miss. Really glad I’m not the only one going through the sensor site issues or bg/calibrate a million times issue.
You guys are awesome.