Medtronic 670 Auto Mode minimum delivery

I have been using the Medtronic 670 since mid December. My main problem is I get a Auto Mode minimum delivery every 2&1/2 hours during the night. I’m not low enough to treat, just low enough set off the alarm. This is becoming disruptive to my sleep. My pump trainer & I have tried several things so far: adjusting my evening meal carb ratio from 1:8 to 1:8.5, setting a temp target at bed until 6am, small snack at bed. So far nothing has made a difference. I could change to manual mode at night but that seems to defeat the whole purpose of the system. Any suggestions?

Are the mm sensor readings accurate? Are u testing with a meter at night to be sure the sensor isn’t giving you false lows?

I calibrate right before bed and the readings I get at night are usually right on with my sensor. Also, I’m not really “low” just low enough to not need much insulin.

I never found that calibrating my Enlites did me much good. Inaccurate by day, and downright disgusting at night (false lows).

Calibrating Enlites didn’t cause it to immediately adjust the readings, unlike the G5, which quickly falls into step, should it get out of calibration a bit, or even quiite a bit, in which case 2 or 3 cals 15 minutes apart will bring a G5 into submission nearly every time.

MM techs get bent out of shape if you tell them you calibrated more than a few times per day…they always assert that it messes with the algorithm. Heck, I just want an accurate system–something that didn’t happen for me other than 2 or 3 sensors over the course of about a year.

But note that we’re not talking about Enlites here. The 670G requires Guardian 3’s. I wore them alongside my Dexcom for about 10 days in advance of starting auto-mode, and I found they were at least as accurate as the G5, or even slightly better. On the whole they do tend to err toward the low side where G5 seemed to err toward the high side, but both stayed within 15 points of finger stick measurements and usually closer than that.

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Yes, I know its now a new gen of sensors for MM, which is why I specified Enlites. Having used 2 gens, I don’t trust them. Besides, often times, the G5 is dead-on and doesn’t have the annoying habit of showing fake lows when I’m lying down.

Basically the pump can’t do anything to raise your BG except to limit how much insulin it’s delivering. There’s some wiggle room in here–the manual says your personal minimum delivery is tailored to your profile by the algorithm:

Alerts you when your pump has been delivering insulin at your minimum Auto Mode basal delivery rate for 2 1/2 hours. Your personal minimum Auto Mode basal delivery rate is automatically determined.

–so theoretically it should tailor a minimum dose to your profile, and set it low enough that you can stay above it through a typical night. But there’s also that hardwired 120 target: if, as a rule, your metabolism is happily cruising along at 110 for hours after bed, then Auto isn’t going to be giving you anything, and that’s as min as min can get, so after 2.5 hours it’s going to yank your chain. Between evening exercise and eating LCHF, I found that I was running into this when I was on auto because some nights I didn’t need anything to stay below target until dawn phenom started kicking. I really don’t think there’s much you can do other than more of what your trainer is suggesting: eat more carbs and adjust your ICR so your BG stays high enough to keep the pump from freaking out because it has nothing to do.

And yeah, it was this kind of thing that after a couple of months caused me to wonder why I was working so hard to keep my pump happy, rather than the other way around, and pulled the plug on Auto entirely.

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OK thanks, I’ll keep tweaking the evening carb ratio. Maybe that will keep me high enough to not alarm every 2.5 hours. Just wanted to see if there was something else I was missing.

I think it is the evening carb ratio. I suggest moving you evening carb but 1, 9.5 to 1. You may also want to think about insulin duration. Most CDE’s set it at 4 and others has found it is a little closer to 3. Depending on where you are bump the duration by 15 minutes until it is hitting at a better place.

We have no idea what the individual duration is, only experimentation will make a difference. If you start trending high back it off. Once my duration was set correctly it just really flowed.

No big changes at once and keep track so you know where you have been and where you are going.

Keep working it, it is so worthwhile.

Appreciate the additional ideas, I’ll change one at a time and see how it goes.

I have no suggestions. I had the same problem. I went on it in Sept. After 4 months, I went back to MM. Spoke to the SR “nurse” which reviews the Carelink Data even to get ideas. Asked the question on the 670G webinar also. All anyone can come up with is calibrating before bed…which I was doing…or eating something before bed…which I am NOT willing to do. I’ve asked the question at different time intervals even to see if Medtronic released anything else they could share about the algorithm or if they came up with other suggestions over time. The pump is NOT a computer. As explained by several people and even mentioned in the webinar, it does NOT learn patterns. It’s more like a calculator. The calculations just take 6 days of TDD and progress forward at midnight. I eat an early dinner around 4pm and all is right with the world. My MB’s were just too small. At night, it would suspend MB’s and put me in safe mode…then eventually bump me all of the way out. My TDD’s usually fall in the 14-17 range. My a1c went from a 6.1 to a 6.5 after 4 months also. I love the idea of AM, I really do, but it doesn’t work for me. I’ve enjoyed reading about all of the pumping books out there though, and feel empowered enough with what I’ve learned, that I’m okay with it and still enjoy the 670. I had the 630 and was very comfortable with it. The new sensors are so much better and with the addition of suspend before low, it was totally worth it. Best of luck to you.

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This worked for me. BG required all during the night was driving me crazy. You need to turn off the auto mode bg alert. To do this go to Options - Smart guard - Auto mode - Auto mode bg alert turn green light off.

Mack, I am thinking about getting this pump next year. So does the auto mode bg alert show if you are going to low or too high? Or is the setting you are turning off more general? I have the MM 530 low suspend pump but haven’t used the CGM sensors since first getting it. I had a lot of issues and decided to go back to Dexcom since it didn’t drive me crazy with alarms. I am worried that if I get this new pump with Automode that I will not like it. So I am thinking about waiting until Dexcom is integrated into a pump.

Might take a look at Tandem.

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I am not familiar with Dexcom but been on the Medtronic pumps for about 8 years and the new Minimed 670G system is the way to go. The Guardian G3 sensors are easy to insert and do a good job matching up to actual BG readings. I work on a farm and the old system taping did not hold the sensor well and after a few days of sweating it would fall off. No problem with the new taping system they now have. In the auto mode it simulates the pancreas which is what you want. Bottom line is the A1C and with this system have dropped to around 6.5.

The BG alert shows for both low and high readings. You can set this to whatever you want. I have attached a picture on the sensor, sensor inserter and pump for reference.

Good luck.

Yeah I have seen that pump before. I wonder how long a closed loop pump option for Tadem will be though. I guess it depends on the timing. I do like my Medtronic pump though. It’s just the sensors for continuous glucose have not done well for me. I have tried them with the last 2 Medtronic pumps and don’t want to waste my money if a I don’t know it will work.

Do you use a Tandem pump? If there was a pump with the Dexcom integrated and will have the auto mode like Medtronic I would probably buy it.

Yes I definitely am interested in the 670. I am due for a new pump next May after my warranty expires. I am just worried about the Medtronic sensors/CGM. I have had 2 Medtronic pumps which I liked but got so frustrated with their sensors that I stopped using them and went back to my Dexcom. My current pump has the low suspend feature and I am not able to use it now because I had too many issues with the built in CGM. I have Hypounawareness and have had a lot of lows in the past so not being able to use that feature has really made me feel like I wasted my money on this pump. Luckily I only had a $500 upgrade fee. I really would have been mad if I have paid a lot more. I think my blood sugar fluctuated too much for the Medtronic CGM. It would set off a million alarms and always be off from my actual blood sugar. I have had several Dexcom CGMs and never had problems. Also any minor issue like a bad sensor they would replace right away. Dexcom seemed really accurate too which helps with low blood sugars and Hypounawareness.

No, I currently use the Medtronic 523 pump and have only used Medtronic pumps. I have always liked their pumps. I have also only used Dexcom for CGM(started with Dexcom Seven). I have always had superb results with Dexcom and heard all the horror stories of Medtronic CGM.

I value an accurate CGM more than I value the pump and I have often said I would go back to MDI before giving up my Dexcom. What good is an Auto mode if the CGM is inconsistent and inaccurate?

Having said that my next pump purchase will be with something that integrates with Dexcom. Sad to say that because I have had good results with my Medtronic pumps.


Yes, I feel the same way. I can’t live without my Dexcom. I have given up two types of Medtronic cgm’s that were built into my pumps. So right now I am leaning towards waiting until there is a Dexcom integrated pump. Well unless some how I was able to do a trial period of the 670 Medtronic pump. I won’t pay $1,000-$2,000 for another one if I’m not able to really use it like now. They offered me a pathway program option for $3,100 with trade in now since I’m still covered under warranty.

I think a while back the Omnipod pump had a program if you switched from Medtronic but I don’t have issues with the pump part.

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The alarms for lows and the auto cutoff (if my husband and I happen to sleep through them) make my Medtronic pumps and CGMs worth it. I’ve never had issues since 1st gen with inaccuracies that were terribly bad. I mean, it gets off within 20 points post meal, but I don’t low carb so I get that.

The 670G has been a hard adjustment though. A lot of tweaking and also just learning it.