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Recent Advances Toward a Viable Artificial Pancreas

October 11, 2010

Claudio Cobelli

Pending a biological cure, the artificial pancreas is the technological cure of type 1 diabetes. Artificial pancreas, or closed-loop control, is a technology designed to mimic the pancreas by sensing, in real time, changes in glucose levels and automatically adjusting insulin delivery to maintain glucose levels in the normal target range. The enormous advances in continuous glucose monitors, insulin pumps, and modeling/control algorithms have resulted in renewed interest and efforts in developing the artificial pancreas, making it more than ever within reach.

The challenge is to design algorithms that can make the right decision, at the right time, with minimal human input. The elements needed to create such an algorithm are based on a structured modular approach. The modular architecture includes three main components:

  • A module responsible for basal-rate and pre-meal control that is adjusted every 24 hours
  • A module to address real-time corrections of insulin delivered as needed
  • A safety module that monitors the risk for hypoglycemia continuously and adjusts insulin delivery accordingly

Such a modular approach allows for incremental testing and potential for increased acceptance by regulatory authorities, offering some user flexibility as each control module can be used separately or within an integrated control system.

The algorithm that dictates insulin dosing instructions for the pump based on the glucose sensing must be rigorously tested before human trials. A milestone was achieved two years ago, when the first model-based computer simulator of the human metabolic system, referred to as “in-silico modeling,” was approved by the United States Food and Drug Administration as a substitute for animal experimentations.  This recent advance has allowed investigators to quickly evaluate the control algorithm in clinical trials. Results of pilot testing in subjects with type 1 diabetes show a significant reduction in the risk of nocturnal hypoglycemia and a greater time spent within the control range.

Despite remarkable improvement in glucose control, the current generation of the artificial pancreas can deliver insulin only after the glucose has started to rise and is unable to blunt the postprandial glucose excursion, or may still experience serious hypoglycemic events. In an attempt to continue to improve the system, investigators are already working on the next generation of the artificial pancreas, exploring a dual or multihormonal approach to glucose control. In normal physiology, glucose homeostasis is regulated by several hormones from the pancreas but the complex interaction between glucagon, insulin, and amylin is disturbed in patients with diabetes. Preliminary results of a dual hormonal control algorithm (insulin-glucagon) as part of the artificial pancreas support the approach.

In the meantime, the artificial pancreas will be based on the interaction between several technologies (glucose sensor communicating with a computer and an insulin pump) and, therefore, it is crucial to develop standards for inter-device communication regardless of the manufacturer. Creating a universal hardware interface will accelerate the research and commercialization of the artificial pancreas. With recent advances in technology, the artificial pancreas is becoming a closer reality and has great potential for improving the lives of patients with type 1 diabetes.

Claudio Cobelli is Full Professor of Bioengineering at the University of Padova, Padova, Italy; and Affiliate Professor of Bioengineering at the University of Washington, Seattle, WA, USA.


For more related articles, click Diabetes Perspectives.