Advocating for the Artificial Pancreas

Editor’s note: A few weeks ago, Kim at Texting My Pancreas let me know that she would be writing a skeptical assessment of the Artificial Pancreas Project (APP), after I expressed some similar skepticism. What appears below is me being the devil’s advocate for the artificial pancreas. While I hold most of these views, I’m not in 100% agreement. Because the APP, if successful, may have an enormous impact on the lives of people with diabetes, Kim and I both think it’s important to weigh the pros and cons seriously. This is just the beginning of the debate. Please chime in by leaving a comment with your thoughts here and on Kim’s opposing viewpoint post.

Conflict of interest statement: I work at a company whose software is used to design, simulate, and (possibly) control various parts of the automated pancreas, but I have no personal involvement in the APP . . . although I’m willing to help out in any way I can. (I also contribute money to JDRF, which is funding the APP.) In addition, among the MathWorks’ various technology offerings are products that can be used for controller design; I make no claims about their fitness for use in a clinical setting. These opinions are my own and may not reflect those of my employer.

Kim has given a very accurate description of the Artificial Pancreas Project (APP) and raised some very valid concerns about it. It’s important to be realistic about what the APP is and is not. We agree that, although it has the ability to change the lives of people with diabetes for the better, it is most definitely not a cure; and it does have a significant amount of risk.

But I don’t think the risks should keep us from moving forward with the APP and seeing it as an important therapy until an actual cure is available. I will lay out why I think it’s important to keep moving forward and trying to get as many people on an AP as safely possible. But first, let’s look at Kim’s three main objections:

  1. She doesn’t want to give up control over her personal treatment actions, especially to a system she doesn’t completely trust.
  2. Neither CGM nor pumps are “fool-proof or absent of errors.”
  3. Faster acting insulins leave little room for error and may lead to more rapid overdose if the algorithms miscalculate or the devices malfunction.

Before I get to each of these, let’s look at why we should welcome an artificial pancreas into our lives. The AP can prevent lows and dampen postprandial excursions. It will get us closer to normoglycemia until researchers develop a true cure to type 1 diabetes. As I understand it, the expectation isn’t perfectly tight “control” — I don’t think that’s realistic to expect from anything other than correctly functioning islets. The goal is to smooth out spikes, eliminate lingering highs, and prevent lows.

Essentially an AP will make the “glucoaster” go away and take most of the burden for balancing insulin and food off the shoulders of people with diabetes (PWDs). We have too many variables to consider when making insulin delivery decisions. In fact, we have heuristics (rules of thumb) instead of rules specifically because we’re treating ourselves without all of the information about the hundred different factors that affect blood glucose (BG), and no one can reasonably expect us to make all of the minute-by-minute decisions required by all those things that affect blood glucose.

Most of us just aren’t as good at achieving our BG targets as we want to be, no matter how earnestly we endeavor to hit them. I’m not being judgmental or suggesting that’s a sign of failure. It’s just a testament to the difficulty of this disease. I think the AP will help reduce the emotional toll of diabetes by helping us get more BG and A1c values that we and our healthcare providers hope to see and by removing a lot of the guilt and despair when our decisions don’t work out as we would like.

It’s natural to be skeptical or hesitant before making big changes, especially when they’re related to our health. But we need to accept our own limitations and fallibility and to accept help from technology when it’s available and reliable.

I don’t want anyone to think that I’m sugar-coating or downplaying the very real risks associated with the AP hardware and with more-or-less removing people from the loop. Every treatment option has risks.* Both multiple daily injection (MDI) and conventional pump therapy have risks. It’s possible to draw up the wrong amount of insulin. Pumps can fail, giving too much insulin or too little. BG meters and CGM sensors can give incorrect information or we can miscalculate the number of carbs in a meal, leading us to incorrect dosing. It’s currently too early to say there is any evidence that the AP has a larger risk exposure than MDI or open-loop pumping.

An AP won’t be any more (or less) fallible than a human pumper. If a pump is going to fail, it’s going to fail. I’ve personally had three pumps fail in about ten years of pumping, one of which led to an overdose of about 40 or 50 extra units of insulin during an infusion set change and two of which led to inoperative pumps. Clearly these are unacceptable events. Every AP pump should be built with even more fault-tolerance and redundancy than the current generation of devices. And it’s likely that some automatic decisions may still require confirmation. For example, if the pump exceeds a certain number of units per hour, the wearer may be required to confirm that they ate or provide an estimate of the number of carbs in the meal.

Based on the kind of questions that the FDA regulators were asking at yesterday’s public workshop, I think the level of testing and validation by the FDA is going to be agonizingly thorough. PWDs will eventually grumble about all the delays getting the AP into our hands. And the legal departments of medical device manufacturers are going to be very reticent to give a thumbs up to any device where “normal use” would cause more risk — and therefore bigger lawsuit costs — than the options currently available.

Furthermore, there’s no requirement that the pumps use the fastest acting insulin available. Patients hopefully will be able to choose whether to use it after consultation with their endocrinologists and gathering feedback from those who are using it. And putting glucose or glucagon in the second chamber of the pump should help reduce the possibility of accidental overdose during normal operation.

Finally, there’s the issue of CGM accuracy. This is the trickiest problem, and the one where I most agree with Kim. I think it’s correct to be skeptical of anything that’s currently in clinical trials — anything that uses CGMS, in fact. Having looked at my own data when I wore a CGM sensor for a week, I saw too many deviations from my BG meter and from how my body felt. Clearly this part of the technology is not sufficient for the fully closed loop that defines the APP.

Does this mean that I’m packing it in? Do I doubt the promise of the whole artificial pancreas project? No. It does mean that I wouldn’t volunteer for a closed-loop trial right now.

But I do think it’s wrong to judge the value of the AP, which is at least 2-3 years away from being submitted to the FDA, using today’s options. What is eventually submitted will have to be much more awesome. Fortunately, CGM technology will continue to improve, and the APP offerings will have to include the most-reliable options or it will likely not be approved.

Is the AP perfect? No. Is it riskier than MDI or open-loop pump therapy. Maybe, maybe not — but that’s not a bad assessment for technology that’s still in the prototype and clinical trials stage. The first regulator-approved offerings (hopefully) will be both more robust and much more accurate.

While it’s important to reiterate that the AP is not a cure — and I sincerely hope that companies selling AP devices never try to market it that way — I think it holds enough promise that I’m willing to set aside my fears about mechanical failures and losing control over the minutiae of a disease that I can’t really control on my own.

* — Remember risk is magnitude of a possible problem combined with the likelihood of that problem occurring.

This entry was posted in 101 in 1001, Diabetes, Health Care, MATLAB, NaBloPoMo, NaBloPoMo 2010. Bookmark the permalink.

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