Artificial Pancreas with current CGM technology?

My doctor has lately been telling me that Minimed/Medtronic is going to close the loop very soon now in providing an artificial pancreas based on today’s CGM and pump technology. Given my own experience, as well as the responses I’ve gotten to my post Continuous Glucose Monitoring with Medtronic/MiniMed Updated, I find this rather difficult to believe. I’m curious whether anyone reading this blog would actually trust their lives to CGM technology telling your pump how much to pump, removing yourself from the loop. However, this peer reviewed article seems to confirm his comments.

Personally, even if I have a way to override this, I would be very uncomfortable with it. For starters, I find the device to accurately track my blood glucose about 80-90% of the time at most. Then, there’s the issue of the 15-20 minute lag. Further, I sometimes have issues with slow insulin absorption, especially during long drives. Unless they combine this with their old implantable pump technology that delivers insulin into the renal vein and unless they find a way to continuously monitor blood glucose rather than interstitial glucose, I think I’m going to have to pass on this.

At least that’s my initial take on the situation. Even at 90% accuracy, it means that it is putting my life at risk 10% of the time. That’s just not acceptable to me. I need much higher reliability. Or, perhaps if I can override the device on days when I know it is not tracking, that would help. More importantly, I think I would want to have to actively confirm that I believe it to be tracking accurately in order to use it. I think that is what might make me trust it, some active confirmation on my part that I believe it working for the next N hours and then I must reconfirm later.

To me, this is still too scary to trust with my life. The reliability just isn’t there. I’ll let you know if I hear or read something that changes my mind.

What do you think?

10 Responses to Artificial Pancreas with current CGM technology?

  1. Before that i have heared that pacrease can not be reproduced

  2. John Paradox says:

    Consider how much technology that isn’t at least, say, fifty years old has problems. One day, when going to the store and stopping at the ATM to get cash, I saw (and, darn it, didn’t take photo of) the screen showing a Windows error message. I’m with Steve Gibson (Security Now! on TWiT), the systems that are mission critical should use specialized OS’s rather than Windows, Linux, or ‘consumer’ systems.
    Also, trying to catch up on the various TWiTcasts, there was a mention of Open Source Voting… which would be IMO far better than the current systems (see Hacking Democracy, available in sections on YouTube)


  3. Steve says:

    Here is an interesting article about the artifical pancreas. The computer program continuously takes in data from a glucose monitor inserted into a patient’s vein and calculates the dose of artificial insulin that needs to be infused through an insulin pump.
    The pump developed by researchers is a double pump – in addition to insulin, it automatically secretes glucagon, a hormone that taps glucose reserves in the liver, raising blood sugar levels when they get too low, a condition called hypoglycemia. Like Scott, I too am a bit weary about giving total control over to a device like this. It would have to be out for a while and proven to work well before I would make the switch.

    Here is the link to the article:

  4. Steve,

    Thanks for the great link!! I had not heard about that. Unlike the technology used by Medtronic/Minimed in their continuous glucose monitoring device, this one tests actual blood sugar rather than interstitial fluid sugar level.

    I would trust this technology with my life.

    I might even rush to be in the test group for this, if they don’t require me to be tethered to a laptop all day long. The difference here is that the foundation of the device is sound, blood sugar, where the fundamentals of the minimed device can’t possibly ever work 100% of the time.

    I hope that they also decide to go with IV insulin delivery rather than subcutaneous, as I have also had issues with absorption rates.

    Either way, I am glad someone is looking into a technology that can really work.

  5. Paul says:

    Hi Scott,

    First, thank you for your CGM posts; they and (which I only found thanks to your blog) have helped me greatly to get value out of my CGM and outsmart the dreaded CAL ERROR in these first three weeks.

    Steve’s article says the IV BG monitor they used was a GlucoScout. Like you, I await the intravenous closed loop gold standard, so I was intrigued. Disappointingly, it appears to be a large-ish hospital bedside appliance rather than a portable device that could replace a SofSensor/MiniLink. So unless they’re proposing to admit us all into hospitals for the rest of our lives, using it to test their software was sort of cheating.

    At this point, I would consider a subcutaneous closed loop if it had a few additional fail-safes built in, though I don’t know what those would look like. It has served me well enough for government work most of the time so far, but the discrepancies are big enough to need to be addressed.

  6. Macey says:

    the 530G insulin pump from Medtronic does NOT make insulin delivery decisions; it ONLY discontinues insulin delivery when the low threshold has been met.

  7. Hi Macey,

    That’s good news and probably fairly safe.

    Do you know if it’s possible to override and take insulin regardless of what the sensor says? I have problems at times, especially on long car rides, where my insulin is not being absorbed so my blood sugar is increasing. At the same time, my sensor is saying that my blood sugar is decreasing and possibly even low because the interstitial fluid is not circulating.

    • Macey says:

      Yes, you can override it. You will receive an alarm and then you are given a choice between suspend delivery or continue delivery. The safety feature here, is that if you don’t hear the alarm and make the choice, then you go into the threshold suspend mode for 2 hours and then it resumes for 4 hours. Now, the idea is not that you use the suspension of insulin to treat a low, but rather you are to treat lows as always taught with sugar. So it’s not just so automatic, you still have to make a decision, unless you are unaware of the alert. If you do go into suspend, you can resume delivery at any time.

      The new sensor itself is much improved. You never see the needle before or after insertion. It is much, much smaller and the accuracy has improved as well. Unlike the current sensor, calibration is not quite as time specific. You can calibrate at anytime unless you have 2 trend arrows. The Soft sensor was very calibration specific or otherwise you would get squirrelly readings which may be your problem with traveling.


      • That doesn’t sound dangerous to me. However, it also doesn’t sound all that useful. But, a better sensor would definitely help. I’m a little worried about switching to the new ones though. I like the angle. I also use silhouette infusion sets. I didn’t do well with the ones that go in at 90 degrees to my skin.

      • Macey says:

        I agree Scott, it doesn’t really sound all that useful to me either; I’m a little disappointed and would like to say ” is that all you’ve got”? Really. I like the MIO 6mm sets. The silhouette I’ve tried, but it’s like a sword.


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