670G: What To Do With A BG

I use a Medtronic 670G & Guardian 3. As any user of this pump & CGM knows, it is not uncommon to be asked to “Enter BG”. However, sometimes I am unsure whether I should let the pump use the BG for calibration, bolus, both, or neither. There are 3 reasons that I may do a BG:

  1. Meal BG: I always do a BG before a meal so that I can include an appropriate correction bolus along with the bolus for any carbs I may be eating. I always do a bolus with this BG (even if it calculates the bolus to be 0), that is pretty much the reason I did the BG in the first place. I usually do a calibration with it as well; my goal is to do enough calibrations this way that I can minimize the need to do other extra BGs for calibration. The only times that I would not do a calibration with a meal BG is if I recently did a calibration (so that I don’t “overcalibrate”) or if my CGM claims I am excessively high, excessively low, or very rapidly rising or falling.

  2. Enter BG Alert: As any 670G user knows, it is not unusual to see an “Enter BG” message. Although this is a pain in the neck, it is worth doing in order to keep yourself in Auto Mode. However, when the result is sent to the pump, I am sometimes unsure whether I should let it calibrate, do a correction bolus, both, or none. I don’t want to “overcalibrate”, but I’m not sure if I will be giving the pump what if wants if I don’t select calibrate. Sometimes it is hard to know whether I should let it do a correction bolus, especially when you are asked for multiple BG(s) or if you recently did another bolus that may or may not still be taking effect.

  3. Calibrate Now Alert: You will see this alert if you ended up waiting the limit before calibrating (which I have occasionally done, especially if it decides it wants one in 6 hours instead of 12 or I skipped a calibration due to one of the previously mentioned reasons) or while doing the initial calibration after inserting a new sensor. I will obviously calibrate with this BG, that is why I did it. However, I am not always sure whether to let it do a correction for the same reasons mentioned above.

I obviously don’t want to do more than necessary with the BG (overcalibrate, do unnecessary boluses, etc.), but I do want it to accomplish the goal that I did the BG for. Can anybody give any input on this? Is there any way to determine whether the BG will satisfy the pump’s Enter BG request? How do you decide whether or not to let it do a calibration? I am willing to do the necessary amount of BG(s), but I still want to minimize them and make sure they are doing what I expect them to. Thanks.

hey there, i have seen your other posts about the 670g and i have been on this pump for about the last 6 months. this is my first pump and i love it, but i dont have anything to compare it to so im a little biased. have you learned of the isig values yet? if not i suggest you call medtronic and ask about it so they can explain better. they told me if the value (which you can find on your pump under status) is under 18 it wont accept the bg or calibration. so before you enter a bg for any reason even if it asks you for one, DONT, because if the isig value is off then it will ask you to change your sensor out after like 3 failed attempts. i JUST learned that about 2 weeks ago.

Don’t worry about feeling biased, I’m probably biased towards this pump, too, and I do have others to compare it to, I love it! I have heard about the ISIG 18 thing that you mention (although it was here, not from Medtronic). There was something similar with my previous pump & sensor (the 530G & Enlite), but with that it was a ratio between the BG and ISIG. Not to say the ISIG 18 thing isn’t how the 670G determines whether to accept the calibration, it just seems like a different way of doing it (an absolute value rather than a ratio). It was only a day or two ago that I learned the ISIG 18 thing, so I haven’t had a lot of time to try it yet. But note that my post was more about what to do when you DO have good numbers. I am often confused and/or frustrated when my pump says Enter BG even when I just entered one a few minutes ago. But thank you for your response, it may be one of the best pieces of knowledge I have for this pump, because with my previous CGMs (even though I don’t expect them to happen as much with this one regardless) the thing that always drove me crazy was the frequent Calibration Error message, and I think that that may actually be the biggest reason I love this one so much!

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I guess it depends on who you talk to at Medtronic. The person I talked to told me you need to divide your current BG by your ISIG number and if the result is between 6 and 16, then okay to calibrate. :thinking: Crazy. I’m wondering if, in the end, it’s the same thing as not calibrating if ISIG is under 18. Interesting that people from the same company give out different information for the same topic.


This is interesting because I was told by Medtronic that I should divide the new finger stick BG by the ISIG number and if it is > than 8.3 or < than 3 don’t calibrate. I have actually entered a BG slightly lower than my meter says just to satisfy my pump to keep it working because the divided value was > than 8.3. When I try to enter a value greater than 8.3 for calibration it doesn’t like it. When I explained to my diabetic educator nurse what I had been told she was surprised as she had not heard this and she has been educating on pumps for many years. She was still using the 20% rule where if the finger stick is off by more than 20% don’t use it to calibrate.

That is almost exactly what I had been told and had been doing with my previous pump & CGM (530G & Enlite), although I learned it all here. I never heard the 20% thing before, although the 3-8.3 thing always seemed to work. But I am now using the 670G & Guardian 3, so I am just wondering if the requirements for an accepted BG are any different. And after hearing so many different ways of determining this (ISIG>=18 uses an absolute ISIG, the BG/ISIG ratio uses both the BG and ISIG, and the 20% uses the SG and BG), I’m not even sure what factors are involved in the requirements.

My comments concerning the ISIG values given by Medtronic were given to me when I had called them concerning problems getting the new 670 and Guardian 3 to calibrate (I was doing everything it asked for which was not the correct thing to do when it kept asking for additional BGs). The most interesting comment that I was told that I totally agreed with was that the new pump when used with the CGM in AUTO mode “was needy” in its constant requirement for attention to providing BGs, calibrations and responding to alarms going off. I finally had to shut off the alarm notifications to keep my sanity and to allow myself and my wife to sleep at nite…she threatened to put a pillow over my head as I could not hear the alarms as easily as she could! And I thought I was going to die of a low blood sugar coma…haha!

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I couldn’t agree more that Auto Mode is “needy” (although it is actually my mom that complains about the constant alerts, even though she is in another room, but she is also the one that insisted that I keep the volume at the maximum level, but sometimes I just turn on the Alert Silence at night, and she doesn’t even know it). I don’t mind doing a couple extra BGs, but when I do them, I want it to respect that I did them (I want doing them to make the Enter BG message go away). But in a number of cases, it just asks for another one in a few minutes after doing a calibration with it. Does it go by some policy of “I used it for a calibration, so I can’t use it for the Enter BG, too”? If I do a BG and don’t use it for calibration or a bolus, will that make it always work for the Enter BG request? “Enter BG” sounds like a simple request, but I think there is more detail as to what it REALLY wants you to do.

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okay so when it keeps asking for one but the isig is good then i would just snooze it at least an hour. usually when the isig is good it should take but then they also mentioned if youre just making up the number it might kind of know that youre faking it. i dont know but now that i am waiting for the isig i have had good experiences when calibrating and not always having that alarm to enter a bg. oh ya they also mentioned your bg having to be stable so maybe that was another issue.
how long have you had diabetes? and how long have you been on pumps?

i wish it was a standard answer across the board. wouldnt that make life so much easier??! ive only been on a pump for 6 months but ive had t1 diabetes for 14 years and im learning so much more about diabetes than before i had the pump.

YES AUTO MODE IS SOOOO NEEDY !!! im just so grateful i found this post because it looks like we’re all going through the same thing. although medtronic isnt giving us the same answers, we’re all figuring it out. Im not glad you guys are struggling but i’m glad there is a community to talk with other people going through the same thing. :slight_smile:

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I’ve had Diabetes for a little over 30 years, but it wasn’t until I believe 20 years or so ago that I got my first pump. It didn’t have a CGM (because they weren’t available at the time), so it only kept the data of the numbers from my meter & how much insulin it put in, along with any errors (such as when it got blocked) & any event markers you could manually enter (although I never used that feature). My first CGM (Enlite) was definitely useful in some ways, but not nearly as reliable or accurate as the Guardian 3. In fact, I never even bothered to upload or show the data to my doctor because the data was so unreliable and had so many blank spaces (from calibration errors and inaccuracies, although they still wanted to see my pump at my appointments for some reason). I remember one thing from when I got the CGM for the first time that frustrated me for (at least what felt like) a long time: Laying on my side or stomach in bed. When I would lay on the transmitter or certain other positions it would cause the sensor to have very low ISIGs and send very low numbers, but I didn’t know that at the time, and I also didn’t know how to silence the pump, so it would claim that I was low and beep at me all night. And my first sensor/pump refused to bring the ISIG back up afterwards, so I was changing the sensor constantly. Definitely the most frustrating and important thing I ever learned about the sensor (although the Guardian 3 is much more forgiving and cooperative about these things). Laying in certain positions also caused the infusion set to some kink, but that didn’t take long to figure out, I learned that within a few weeks of getting my first pump. There are other things that words cannot describe, because they are so unique to every person, and sometimes they change over time. But I think you sound like someone that is a very quick learner, so before long, you’ll have your pump & CGM working at full power (and that doesn’t mean Max Delivery, if you want a lame Auto Mode joke!)!

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thank you for sharing your experiences! i love that only us as diabetics would get some of these jokes, its nice to joke about it and laugh. I often keep it to myself because a person without diabetes let alone a pump would not understand!!