Science Translational Medicine: Artificial Pancreas Could Help Control Type 1 Diabetes
An artificial pancreas that uses a computer algorithm to balance sugar levels in the body could help patients with type 1 diabetes better control the disease, reports a new study in Science Translational Medicine.
Depiction of the bihormonal closed-loop control system used in the clinical trial. The controller responded to venous blood glucose measured every five minutes using the FDA-approved GlucoScout (International Biomedical) and commanded insulin-glucagon control doses. The doses were administered using FDA-approved Deltec CoZmo infusion pumps (Smiths Medical). | Image courtesy of El-Khatib et al., Science Translational Medicine, 14 April 2010
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The device may eventually run on a computer chip as part of a fully wearable artificial pancreas system, and may revolutionize treatment for the some 285 million people worldwide currently living with diabetes.
In Type 1 diabetes, the pancreas stops producing enough insulin (a hormone that lowers blood sugar) and releasing enough glucagon (a hormone that raises blood sugar) to properly control blood sugar levels in the body. Currently, the only way for patients to stay healthy is to artificially maintain a delicate blood sugar balance in order to keep levels from dipping too low or spiking too high.
This involves day-and-night selfmonitoring of blood sugar and injections of insulin, along with a strict diet and exercise. Even with a vigilant lifestyle, patient’s blood sugar can still dip to dangerously low levels—a condition known as hypoglycemia.
Previous attempts to develop an artificial pancreas have focused only on supplying insulin, and so failed to prevent hypoglycemia. Now, Firas El-Khatib of Boston University and colleagues have developed an artificial pancreas that delivers both insulin and glucagon as needed, closely mimicking a normal pancreas.
The artificial pancreas is composed of a continuous blood sugar monitor, two pumps that inject the hormones under the skin, and a laptop running a computer program that allows the two pumps to “talk” to each other and calculate how much insulin or glucagon a patient needs at any given time.
Using the artificial pancreas, the researchers were able to control the blood sugar of every person in the study—without any hypoglycemia. Testing of a more portable artificial pancreas—where the computer program runs on a tiny chip instead of a laptop—is currently underway.
The artificial pancreas may just be one part of the solution to diabetes being produced by emerging technology, according to a related Perspectives article in Science Translational Medicine.
The pancreas’s glucose regulatory pathways: Insulin secretion from the beta cells of the pancreas results in glucose uptake and gluconeogenesis by the liver, up-regulation of the GLUT-4 glucose transporter in muscle, and attenuation of glucagon secretion from the islets. Glucagon secreted by the alpha cells stimulates glycogen breakdown by the liver, thereby releasing glucose in times of need. Somatostatin secreted from the delta cells attenuates both insulin and glucagon secretion. Amylin secreted by beta cells delays gastric emptying, decreases appetite, and suppresses glucagon secretion after a meal. Cells within the islets are in close proximity to one another. This image relates to a Perspective paper by Larry Brown and Elazer R. Edelman. | Image C. Bickel/Science Translational Medicine
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Larry Brown, professor at Massachusetts Institute of Technology, writes that while new “smart” technology might be able to relieve some of the burden for patients, controlling blood sugar in diabetes is a lifestyle.
There are myriad factors to consider when attempting to artificially control blood glucose. For example, the hormone glucagon is inherently chemically and physically unstable and presents significant drug development challenges.
Although increasingly sophisticated blood glucose control algorithms continue to be developed, not all of the factors that influence blood glucose control can be programmed, Brown writes. Diet, exercise, and the subtle, complex ways in which each individual responds to insulin are all critical to instantaneous glucose control and cannot be predicted.
The quest for greater control of blood glucose will inevitably improve with advanced technology, he said. But until there is a cure for diabetes, the influence of patient’s lifestyle choices on controlling the condition will remain the most significant.
Science Translational Medicine, the newest journal from Science, focuses on outstanding science with promise to improve human health and quality-of-life. Under the direction of Elias Zerhouni, chief scientific adviser and former director of the National Institutes of Health, and Editor Katrina Kelner, the journal aims to publish groundbreaking research from basic biology that will help make significant advances in medical care, along with commentary on the latest issues in translational medicine.