Medtronic 670G: Experiences of a Mom + Daughter with T1D


Medtronic 670G Insulin PumpMy 15 year old daughter and I both started on the Medtronic 670G system in July. With 2 1/2 months of use under our belts, we have had common, yet unique, experiences with the Medtronic 670G tech.

As many people report, some magic happens between weeks 3 and 5. There was a turning point in which we both became happier with the results and user interface/ demands.

[Our initial experience, one week in, is documented in this piece: A Nurse’s Review: Medtronic 670G Insulin Pump.]

Chew on this: I don’t buy juice anymore.

This is huge, especially in a household that has two very active people under one roof – that both have T1D. I had the habit, on occasion, of pouring my daughter 3 glasses of juice overnight after a big basketball practice or some crazy family adventure in the mountains. I can thankfully report that this behavior is a thing of the past.

Like it or not, midnight picnics are common for those of us living with type 1 diabetes. Our dentists may agree that the 670G may be worth it’s weight in gold with the simple elimination of the sugar bath on our teeth all hours of the day and night.

Hands down, the best feature of this pump/ sensor combo is the near elimination of hypoglycemia (low blood sugar) – particularly overnight when we are at our most vulnerable.

Over the past few months I have put this thing to the test. I trained for and completed a 102 mile bike ride for JDRF Ride to Cure in Loveland, Colorado. I’ve spent a lot of time in the saddle with this sensor and pump over some strenuous miles at higher elevations.

My overall impression is quite positive at this point – I have no desire to go back to my previous pump or a pump/continuous glucose monitor (CGM) that don’t speak to one another.

Do I have high blood sugars? Yes.
Do I get frustrated? Yes
Are there gaps between my blood glucose and sensor glucose readings? Yes.
Is this system the best we’ll see? No.

The Medtronic 670G is a work in progress that will only continue to see improvements – and competition – over the next few years, but for now, it’s king.

My Positives:

  • Quality sleep improvements – Because my sugars are normal overnight, as are my daughters, sleeping has seen huge improvements. I’m worried less about her having lows overnight.
    ***I haven’t had 1 overnight low since I started on the 670G.***
  • Exercise – I do really love exercising with this system (minus the fact that there isn’t information sharing – so I can’t see my sensor reading on a watch). If I want to see my sensor reading, I have to take an awkward glance at my pump that sits on my waistband – with the updated vertical screen. This may be the death of my neck – so awkward from the user’s perspective. Medtronic would be well served to have a physical therapist on their team analyzing how their new products impact a person’s movements.
    I choose not to use the “temp target” feature for exercise, it always makes my blood sugar creep into the 200 range. I leave my pump as is, and eat free carbs throughout my ride – this is the only time I don’t tell the pump that I’m eating.
  • Eating – Eating is a new thing. I’m a thin person and not looking to lose weight, but I lost 7 pounds without trying. I’m actually trying to gain it back – my body, I think, is like – “Hey! Where are all the simple sugars?” I have actually been in bed trying to fall asleep, realized I was hungry and went to the kitchen to eat.
    It’s been an interesting transition for me, after 30 years of diabetes, not having to eat in order to keep my sugars in line. The adjusting micro-basal is so smart. I’m eating more healthy whole foods and larger portions at meals than I used to – I’m also getting more accustomed to this new pattern of “not eating for diabetes.”
  • Adjustments – There are only a few things to adjust on the back end with this pump – namely the active insulin time (AIT) and carb ratios (CR). Most people find themselves settling in with a 2 hour AIT or the pump won’t correct a high blood sugar in a timely manner. Carb ratios undergo serious changes for most people – especially those of us that had high basal rates prior to the 670G.
    When bolusing for meals, the micro-basal usually shuts down altogether. I believe this is why we need such tight carb ratios. It’s a bit of a science experiment to find the correct CR’s.

My Negatives:

  • Low blood sugars: As I mentioned previously I hardly ever get lows, but that doesn’t mean that the sensor doesn’t give me incorrect warnings.
    When this happens – and I’m not actually low (verified with a BG test), the micro-basal delivery turns off. During this time, if it’s telling me I’m 50 and I’m actually 100, it’s one of those times that you shouldn’t enter your BG or calibrate because the gap in numbers is too wide.
    So, if you leave the pump/sensor “as is,” it will result in a high blood sugar -  rather than leaving you at your excellent BG of 100. Yes, frustrating.
    I choose to revert to manual mode when this occurs or sometimes take insulin and eat carbs without entering a blood sugar and that helps bridge the gap. But ultimately, it means another BG to get things squared away with the sensor – usually 20 minutes later.
    And speaking of alerts, this system took a large step backwards without the communication piece to mobile phones and watches – especially if you are a parent of a child living with T1D. This pump/sensor duo isn’t the end all, it needs parental interventions. Kids need reminders and they really dislike when we have to look on their pump screen to find the data we are looking for. Nightscout has a workaround, but it demands a glucometer be attached to the the users phone. My highschooler would never go for that.
Arrow is pointing at the micro-basal delivery

Arrow is pointing at the micro-basal delivery

  • Sensor Life: Initially, I had some serious sensor failure issues. I would get the “Updating Sensor” warning which would ultimately end up with a failed sensor, on a regular basis. I have had 3 or 4 sensors last the 7 days they should since I started on this pump (ugh).
    I have figured out that there is some kind of an issue with my 670G and my work in recovery room at the hospital as a nurse. All I can figure is that the “loop” between patient cardiac monitors and vital signs that feeds information to the bedside computer is interfering with my “670G loop.” Medtronic doesn’t have any suggestions other than using manual mode which is unfortunate.
    *Medtronic did send me a new transmitter and that has helped with failing sensors a bit. They have also replaced every failed sensor.*
  • Algorithms: It takes a bit for the pump to “get to know you.” If you’re anything like me, I have my regular stuff, but I’m not the most predictable person in the world. Some days I’m working, some days I’m riding my bike 50 miles. I think the more predictable our behaviors are the better results we get from the algorithm.

Medtronic 670G

  • A Higher A1C? Well, I’m not sure if I should classify this as a negative, but I know my A1C will be higher. The predictive value on my pump for my next A1C is 6.8 – not bad – but I’m always 5.9 – 6.1.
    Here’s why – there are no lows to bring that value down. It is a solid 6.8 that I’m continuing to make pump adjustments for. This pump rarely keeps me at 120 like it says the target is, I often wish it adjusted me a bit tighter. I often check and I’m 140 when it says 120 on my sensor. I wish it had the option to adjust to 100.
    Rarely do I have sugars in the 80′s and 90′s like I once did. But I also had lows or was averting lows throughout the day.

I think with this tech comes the realization that our once coveted A1C value will change – and so should our perspectives about them.

  • “The Loop”: This endearing term (tongue in cheek) stands for one of the most frustrating things that occurs with this pump. The 670G, especially when fed too much information, or information at inappropriate times – freaks out.
    The best solution to this problem is to treat your pump like a 2 year old having a tantrum. Don’t feed into the issue at hand. Be patient, wait and don’t enter information if the BG and SG are more than 30% off, or you will experience the dreaded loop. Is this inconvenient? You betcha.

I realize nothing is perfect. As a parent of a child with the same 24/7 deal, I appreciate some aspects of the 670G, while I’m not so hip on the others. I’ve always said if our kids can have normalized blood sugars overnight, then that’s half of their life within range. That’s pretty impactful – right?

Kids aren’t as attentive as the average adult and this pump isn’t “hands off,” it has it’s odd set of demands – and they can be confusing. I’m most concerned with the negative feedback loop that occurs when the pump is asking for information, but it really doesn’t want you to enter it, or you will confuse the already confused system, and it may result in an aborted sensor.

With kids we are constantly drilling into their heads – “Just do it!” But with the 670G it’s become – “Don’t just do it!”

It requires thought, patience, and sometimes it’s a serious waiting game. But what kid wants to – or will – revisit diabetes 20 minutes later, when it keeps pestering with a beep or vibration to calibrate or enter a BG that the system might not be happy with. This is a serious flaw for a system built for all-ages.

My Daughter’s Positives:

  • “No Lows!”
  • “I like having the CGM and pump in one unit; when I’m at basketball, I can look and see what my sensor glucose is.”
  • “That it’s waterproof.”
  • “The sensor/ transmitter is really flat compared to the Dexcom and I like that – it’s less visible under clothes.”
  • “You can silence all of the alarms for a period of time for school and sports.”
  • “The pump prevents post meal highs when you nail the carb load correctly.”
  • “No overnight lows – I sleep better and can sleep in without getting low.”
  • “There is a setting to deliver insulin faster – I like that.”
  • “My A1C is improving a lot.”
  • “I don’t have to eat for diabetes all of the time.”
My Daughter’s Negatives:
  • “The red flashing light brings attention to the pump and me.”
  • “I have to take the pump off to use it now that it is situated vertically, not horizontally.”
  • “You have to count EVERY SINGLE CARB.”
  • “I get popped out of auto mode almost every single night – even with calibrating right before bed.”
  • “The pump alarms don’t wake me up from my sleep.”
  • “I’m still trying to gauge when to use the temp basal for sports or not – I’m not getting consistent results – sometimes the temp basal makes me high.”
  • “Sometimes it doesn’t give me one alert, they keep stacking on top of one another and takes time to work through them all.”
  • “The pump is bigger and more noticeable.”
  • “The battery only lasts 2 weeks and dies quickly – it’s larger – a AA. “
  • “When you calibrate it doesn’t give a number right away like my Dexcom did; I miss my Dexcom.”
  • “It bugs me that I can’t use my Apple watch or see my pump/ CGM data on my phone. Especially when I’m wearing a dress. You always have to pull your pump out to do anything.”
  • “There is a lot of button pushing to do for everything on the pump – much more than previous pump models.”

If you start on this system, I recommend joining one of the 670G Facebook groups. They not only provide a community of support, but it gives us crowd-sourced information from users, outlining the successes, technical issues and workarounds people are using that may not come with our training.


  1. Katlyn Agosta says:

    Thank you for such detailed reviews of the 670g. It has helped tremendously to understand the true duly demands of this system. I’m currently using the Animas Ping with Dexcom G5 and feel I would miss this CGM if I switched. Weighing my personal pro and con lists as my warrenty expires next month (big deal now that Animas pumps are going away). Stress much?! ;)

  2. Phil King says:

    Thanks for this very helpful, thorough review. Especially to have two people’s perspectives baked into one writeup!

    I’ve been using the 670G for about 3 months and have been “closed loop” for about 2 months. I just got off the phone with Medtronic to report the last 5 (*five*) sensors that have failed to last more than 4-5 days over the past month. On the plus side, Medtronic support is very helpful and it only took a 15 minute call to get replacements arranged for all 5 of those sensors. The downside is that the sensors are fundamentally untrustworthy and its been a near daily high maintenance relationship. I also exit auto-mode almost every night because calibrations don’t last long enough for me to sleep through the night, and frequently the pump doesn’t accurately predict how long it’ll be before the next calibration is required.

    I’ve had inconvenient premature sensor failures that have resulted in a very bad low BG (which I didn’t feel, which is also bad) and currently have a sensor that was reporting 180mgdl when my BG was actually 390mgdl. Earlier today it was telling me (and a felt) low, so I ate food to correct… now spiked like crazy.

    So far I’ve used 2 boxes of Guardian sensors in auto mode and 8 of the sensors have failed with 4-5 days. The other two failed before 7 days. Its remarkable that they’re allowed to advertise these as 7 day sensors… the rep who did my training said the average they’re seeing is closer to 5.5 days. That means 50% of users are seeing even shorter times before failure.

    I have used Dexcom sensors for at least the past 2 years and I miss it every single day. So far I probably am avoiding unexpected low BGs with the 670G, but the maintenance and the dangerous-seeming lack of reliability makes me regret the move. I’m going to speak with Medtronic this week about getting a refund… or I’ll just turn all this junk off and switch back to Dexcom and use my pump in dumb mode.

  3. diabetesknow says:

    Thank you so much for the 670g detailed insight. I’m currently using the minimed 530g system and it has been Ok. Only problem is the delayed blood sugar readings. I was looking forward to upgrading to the 670g but I can’t upgrade until 2019 due to insurance. Then I read about the iLet (bionic pancreas) by Beta Bionics. All you have to input is into the device is your body weight when you first start it then it learns about you and acts like a real pancreas. Kenny :)

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