Automated Insulin Delivery System, Not an Artificial Pancreas

Anne L. Peters, MD


May 24, 2023

This transcript has been edited for clarity.

I'd like to clear up the confusion about whether or not there is such a thing as an artificial pancreas. First, we know that we have pancreases and beta-cell transplants that work. An artificial pancreas is different, and it's actually an old term for what we now call automated insulin delivery (AID). Those systems are not an artificial pancreas; they are ways to deliver insulin to patients with type 1 and type 2 diabetes.

We have, within the category of AID, the hybrid closed-loop systems. These are systems like the Tandem Control IQ, the Omnipod 5, and the Medtronic 780 G that give insulin continuously on the basis of values obtained from a sensor. These systems are really good at basal insulin because when somebody is not eating, or if it is overnight, they can keep glucose levels really flat.

These aren't fully closed-loop systems because the individual still has to interact with the system and give doses for meals and then adjust doses for exercise. This is often really tough for patients because they need to give a dose in advance of the meal, and they have to figure out how many carbohydrates they're eating. If they're going to exercise, they have to reduce the insulin that they're given 1-2 hours before exercise.

This makes spontaneity in life difficult, and if done wrong, people can end up being either hypo- or hyperglycemic. It would be really great to have a system that was a fully closed-loop system that didn't require that someone to do all of these things.

A couple of weeks ago, I went to a National Institutes of Health conference on automated insulin delivery systems, and for 2 days, I sat and listened to the most genius people in this field. They're amazing human beings who are really dedicated. I was hoping for the answer, for the magic, for the reason why we can't do a fully closed-loop system and what we're going to do about it.

What I learned is that the limit — and I guess I should have realized this — is that we're giving insulin subcutaneously. Subcutaneously delivered insulin has a problem, which is that you give it, it works however long it takes it to work, but then, it takes 4-6 hours to wear off.

Whatever algorithms you use for giving insulin as glucose levels are going up, whatever wristband you can have someone wear to see if they're eating or not eating, and for anything you do to help reduce the postprandial rise, you then have to figure that there is no brake.

Basically, you can't get rid of the insulin once it's been given, and glucose levels will fall if the insulin is stacked too much in advance or with the increase of the glucose levels with the meal. Somebody said, which I think is really apt, that it's like an engineer trying to design a car with only a gas pedal and no brake.

I think that's what makes all of this very hard. We put much of the onus on the system user to do many things right. The system does things for the patient, but it isn't enough. It is not a fully closed-loop system.

There are some really cool things on the horizon that will help people do better. There is the Tidepool Loop algorithm that's been approved and should be ready to be used in the not-too-distant future. There's also a new pump. Beta Bionics has been working on developing an insulin pump. Originally, it was going to be insulin and glucagon together, and it will be in the future. Right now, what's up for approval is the insulin-alone pump.

The reason this pump stands out from all the others is because the user basically is not allowed to fidget with it. When you start someone on the pump, you put in their weight, you choose one of three different target ranges, and then the pump just works. The user can put in if they're eating, but they only have three choices: they're eating a usual amount, more than usual, or less than usual.

There are no numbers that the user puts in here, which I think makes this a spectacular tool for my patients in my East LA under-resourced setting who have trouble with those sort of numeracy skills. This system is going to get people's time in range of 65%-70%. For people who have goals that are tighter than that or who prefer to work with their own insulin to try to reach a time in range of 80%-90%, this isn't the system for them.

I have many patients who were very good at adjusting their own insulin and doing it on their own, but this is for people who don't want to or can't make those adjustments, whose time in range is much lower, who perhaps are transitioning from multiple daily insulin injections, or who are adolescents, for instance. There's a whole group of people for whom I think this kind of system will really be a relief. It will help take away some of the burden.

They do have to think about such things as changing the infusion set, charging the pump, and dealing with times when their glucose levels are persistently high. There is still troubleshooting. It's still a pump, but I think it's going to be another option for our patients along with the existing options.

I couldn't be more excited about the progress that is being made in this field, but don't use the term artificial pancreas. That's not what we're giving patients. We're giving them automated insulin delivery systems.

I think we need to encourage all our patients with type 1 diabetes who have access to these systems to use them to improve their control — if it's the right system for them.

Anne L. Peters, MD, is a professor of medicine at the University of Southern California (USC) Keck School of Medicine and director of the USC clinical diabetes programs. She has published more than 200 articles, reviews, and abstracts, and three books, on diabetes, and has been an investigator for more than 40 research studies. She has spoken internationally at over 400 programs and serves on many committees of several professional organizations.

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