Shawna Wood would like nothing better than to go back to bed for another 24 hours of perfect blood sugar control. The 50-year old Wilsonville, Ore. woman has Type 1 diabetes, and she recently took part in a clinical trial of an automated replacement for her pancreas, which stopped producing insulin 9 years ago. She and 12 other Oregonians with Type 1 diabetes tested an "artificial pancreas" using a new approach in a trial with Legacy Health's research program.
“It was like not being diabetic anymore”
Type 1 diabetes is an autoimmune disease that attacks the beta cells in the pancreas. The beta cells produce insulin, which regulates the body's metabolism. Without insulin, the blood sugar level in the blood rises to dangerous and even fatal levels. An artificial pancreas measures the level of sugar in the patient's blood with an inserted sensor, and dispenses insulin based on the measurements.
Because some first generation artificial pancreases only dispense insulin, researchers are looking to ensure that people can avoid very low sugar levels, or hypoglycemia. In people that do not have diabetes, insulin works in concert with glucagon, which is produced by the alpha cells in the pancreas. The delicate balance of the two hormones has never been replicated in humans by a mechanical device - until now.
W. Kenneth Ward, M.D., a senior scientist at Legacy Health, led a group that investigated the combination glucagon and insulin therapy in an artificial pancreas. There were 21 experiments in which the device was tested for approximately 24 hours, and the incidence of hypoglycemia was markedly reduced. In fact, nighttime hypoglycemia was reduced nearly to zero.
Wood said the two trials were rejuvenating.
"It was like not being diabetic anymore," she said. "I've had some short-term memory problems since I became diabetic, and when I came off the trials my thoughts were clear and focused."
She attributes the "fogginess" to the fluctuations in her blood sugar levels, which range from low to high over the course of a day. Regular self-testing and insulin injections are an imperfect means of control, and the reason the development of an artificial pancreas is so important.
"These results suggest that an automated system of bihormonal therapy is able to control glycemia safely and effectively in people with Type 1 diabetes," Dr. Ward said. "The average glucose level during the trial was 138 mg/dl, which is very good diabetes control. A person with diabetes who could achieve that level of control over many years could probably avoid diabetic complications such as eye disease and kidney disease."
Dr. Ward's study was published March 23, 2010, in the journal Diabetes Care. Confirmation of the work appeared just three weeks later, when a research team in Boston published a similar study (but one that used a different computer program for controlling blood sugar) in the journal Science Translational Medicine.
Dr. Ward's group receives its major funding from the Juvenile Diabetes Research Foundation (JDRF), as one of the teams funded by its Artificial Pancreas Project grants. JDRF funding will continue to help Dr. Ward refine the artificial pancreas. The work is also funded by the Legacy Good Samaritan Foundation and the National Institutes of Health.
The team will next turn its attention to better automation and miniaturization of the system, and discussions are in progress with pump manufacturers for a bihormonal pump. Work also is ongoing to develop a faster-acting insulin that will work better in an artificial pancreas, and on ways to better stabilize glucagon, which can break down over time.
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