An artificial pancreas, sometimes called a “closed-loop” insulin delivery system, is a mechanism that delivers insulin via an insulin pump in amounts dictated by changes in blood glucose and other factors that influence insulin requirements. Several prototype devices are currently being tested in clinical trials, and researchers hope that a fully automated artificial pancreas will be on the market soon.
Any artificial pancreas consists of three components: an insulin pump, a continuous glucose monitor (CGM), and an algorithm for computing the correct amount of insulin to infuse. An insulin pump, which first became commercially available in 1980, can provide variable basal infusion to replicate the slow trickle of insulin the healthy pancreas makes all the time, as well as individual boluses to mimic the extra insulin the pancreas secretes in response to meals.
The first commercially available CGM arrived in 1999. CGMs measure glucose in the interstitial fluid, the fluid under the skin, with a tiny implant under the skin. A lag time of about 4 to 10 minutes exists between fluctuations in blood glucose and corresponding changes in the amount of glucose in the interstitial fluid.
The third component is a computer algorithm for determining how much insulin to infuse. However, predicting how much blood glucose will rise following consumption of a meal has proved challenging. A recent model of algorithm, Model Prediction Control (MPC), incorporates a model of the patient’s metabolic system to predict and react to changes in blood glucose in a preplanned step-by-step fashion, much as a computerized chess simulator plans chess moves based on the opponent’s moves.
Studies of the artificial pancreas once were carried out only in a hospital setting, but these studies have been moving out into the real world. In several multicenter studies carried out over the past few years, patients have used these “closed loop” systems on an outpatient basis. In these studies, those using an artificial pancreas have been shown to spend less time in the high and low blood sugar ranges and more time within the normal range. In one case, patients were able to use a smartphone app of the algorithm for determining doses, but more studies are needed before the artificial pancreas can become more widely available.
Want to learn more about the artificial pancreas? Read “Artificial Pancreas for Type 1 Diabetes Receives FDA Approval” and “Four Crucial Artificial Pancreas Trials Getting Underway.”