Dexcom and the Artificial Pancreas

I keep reading on the Facebook Dexcom group page about the Dexcom sensors failing, or equipment needing replacement. Can you imagine what would happen if, a few years from now, you were wearing an Artificial Pancreas (AP) and a false reading from the Dexcom component in the AP occurred? You could get insulin from the AP when you were not actually high, or glucagon when you were not actually low. The AP is going to depend on the Dexcom numbers to know when to give you insulin or glucagon. All it would take is one bad number from the Dexcom to give you an overdose of insulin or glucagon, and send you to the ER with a very serious situation. This is a major concern of mine!

This discussion is drawing a lot of replies on my Facebook page, and I am told that I should not criticize a device that will not be available until a few years from now. I don't mean to imply that the AP will not be accurate, I am concerned for the people who do not have the good luck with the Dexcom that is currently used. They may not have much better luck with the G6 sensor that is now being developed, although it is supposed to be much better than the current sensor. The G6 is awaiting testing and FDA approval. It will be wonderful if the G6 sensor is so accurate that we can trust the AP when it materializes.

Actually, my concern is for my friends. Medicare will not cover a CGM, so I am sure they will not cover an AP either. I will probably never get to use the updated Dexcom or the AP.

I've also wondered about running my rig through an iPhone. I have a 5s and the battery needed to be replaced, although I didn't receive a notice or anything, it just would crap out all the time, particularly using Instagram in remote areas, with no wifi (ok, once was on top of a volcano on Maui...) and, the thing would go from like 78% battery to zero and kill the phone, although it would immediately spike back up to 65-70% immediately upon being plugged back in, not really something I'd want in a medical device.

Stating this up front, I am no expert on the AP(Artificial Pancreas) nor have I participated in a trial yet. I have however been to a great presentation on the Oregon Health Sciences University AP program. It was given at this years ADA Expo in Portland where one of the systems was available to look at and check out the Phone app it uses.

Some of the key points I took away from the talk:
1. The doctors involved are fully aware of the limitations of current technologies, specifically CGM's. I gathered this is lower on their list of worries, since the technology is evolving extremely rapidly.
2. The main issue currently is that they don't have a stable Glucogon compound. The one they have currently can only be used in the pump for <14 hours before it degrades. This alone is a deal breaker, though research is underway to find a more stable compound to use.
3. Current rapid acting insulin isn't rapid enough by quite a lot. This is another deal breaker and may be one of the hardest to overcome.
4. The current AP they are testing requires input of some kind when taking a meal/snack before it delivers a bolus(it depends on the AP trial you are talking about). Whether it auto-corrects on its own, I failed to ask.
5. It still uses a basal insulin program, as far as I could see the same as the standard pumps do now.
6. A true AP is a long way off, the speaker wouldn't even give a guess. I wouldn't expect it in 5+ years at least, I have a feeling it will be 10+ years.

These are just a few of the highlights I took away from the talk. I have to say, the folks running these trials in Oregon are the ones that give T1's like me hope. They are realistic, but undaunted by the challenge.

Kevin, thanks so much That is an excellent update on the AP!!

Thanks Richard!
On a side note, Oregon Health Sciences University is currently recruiting patients for another AP study. This one is to test out the use of their system to stabilize BG's during and after strenuous exercise. Alas, I was too old (45 years max) and I'm currently taking an immunosuppressant for a skin condition. I will likely get in a trial later this year once I'm off they pills!

Kevin, I admire you for participating in an AP trial. I have read reports from two Facebook friends who have done so, and they were very closely supervised. It sounds like a very safe procedure. Good luck with it!

D-tech is maturing rapidly. The Dexcom 505 firmware update brings the G4 to 9% mean absolute relative difference or MARD. Current fingerstick meters are rated in the mid-5% MARD range. The 505 update dropped the MARD from 13% to 9%, quite a leap. I don't think it'll take much time before the sensor technology improves to at least meter range accuracy.

I've read reports about the development of glucagon stable at room temperature for extended periods. I think that better glucagon formulations are not that far away.

Some of the programming work must be fail-safe programs that guard against corrupt data driving an insulin overdose. I imagine much work is being done for self-check corrections to ascertain the validity of the data and if faulty data is found then the AP would default to a benign setting and alert the user.

So I ran into this video link on another site.
Artificial Pancreas Talk
Clearly, the Boston researchers are further along than we are out here on the West Coast.
I only wish he'd explain how they have overcome the Glucagon stability problem. I'm assuming they are using the Xeris Pharmaceuticals glucagon product.

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Agreed, I find it baffling, too, given how unreliable CGM technology seems to be at present. CGMs can be exceptionally helpful, especially in shedding light on trends, but I cannot imagine making insulin-dosing decisions based on my current Dexcom G4. Insulin lag is obviously an issue too, but that at least can be ameliorated with sophisticated computer processing.

anyone interested in changing the current situation with Medicare not covering cgms might want to check this out

Please keep in mind that "unreliable" is in the eye of the beholder. There is not a general issue of reliability or accuracy of the G4. There are particular patients that have problems with it.

Similarly, there are others that have better than average results. I'm one of them. My G4 is always reliable and accurate -- scary accurate some times -- until the sensor starts to die 2-3 weeks out.

Your G4 seems accurate enough to dose insulin? Mine is very far from that...

I know a few Joslin medalists with 50+ years of type 1 who do bolus from their CGM's and rarely test. They say that is not causing any problems.

I suspect I'm too lean for that--I get decent reliability, but nothing even close to numbers I'd be confident dosing off. And that's just during week one, rebooting a sensor for a second weak is generally almost useless.

The newer Dexcom CGM with the G4 sensor is reputed to be very accurate, but the Medtronic CGM with the Enlite sensor has a bad reputation, rarely being accurate for many users. I used the older Dexcom a few years ago, before the G4 was created, and it gave me no help…there was so little accuracy. I would be happy to use the Dexcom G4, but Medicare does not cover CGMs.

Well everything I currently use to manage my diabetes can fail at any time. Pump could lose it’s charge or a battery runs out or my meter shuts down and won’t turn on. Every piece of equipment I use could fail. That’s why I have so many back ups. I’m all for anything that will make this easier even if not 100%. I have learned over the years nothing is for sure and everyday is a crap shot. And I will continue to volunteer for trails happening in my area to move this cure a long. Been waiting a very long 44 years so far.

Good point. True dat.

31 for me, and they’ve been saying “A cure is just 5-10 years off!” since the day I was dx’d. So I react to all of the AP talk with a healthy bolus of realism. It sounds like there’s going to be a lot of (I’m quite sure) very expensive proprietary insulin and glucagon involved, as well as the hardware. The health insurance carriers aren’t going to be handing these out to every T1 who wants one. Just getting qualified for a CGM still takes some doing and the co-pays are hardly insignificant even for those of us with generous coverage.

On edit: I don’t expect those of us on the older end of the T1 spectrum are going to be the priority recipients.

I still think they should consider the “Minority Report” route for avoiding bad data (from CGM).

Current glucagon is so freaking expensive, i can’t imagine the cost of an newer version used on a daily basis.

I think the AP has a long long way to go. It’s not just CGM accuracy, Glucagpn & Insulin speed problems but also the whole uncertainty of the current products. Good insulin delivery depends a lot on infusion set placement, is it in a good spot, no fatty build up, not in a blood vessel. no kinks in the canula etc. CGM also depends a lot on the site selected. For the Dexcom is the transmitter attached properly etc. Then the whole problem of occlusions not just for the insulin delivery but now also glucagon.

That’s why I am far more interested in smart insulins & a cure, the research on encapsulating beta cells & growing them from our own cells is much more interesting. I know I wont live to see it but it is nice to think of better things for those to come. As others said us old timers wont be at the top of the list for anything new. Actually I should have died about 20 years ago!

you don’t need a cannula. Sure-t’s, which I use are simpler–just a steel needle which is thinner and very comfortable.