That's why they decided to add glucagon to their artificial pancreas to give it an added level of protection, said Russell.
In the current version of the device, the researchers tracked blood glucose via a special sensor placed into a vein. Future versions of the device will use currently available continuous blood glucose monitors (CGMs), but for this trial the researchers wanted an extremely accurate way to measure blood sugar levels so that the only variable was the mathematical formulation used to program the delivery of insulin and glucagon.
Eleven people with type 1 diabetes were included in the initial tests, and were studied in 27-hour experiments. During that time, they were hooked up to the artificial pancreas and given carbohydrate-rich meals (carbohydrates are transformed into glucose in the body).
The device responded to the rise in blood sugar levels by administering insulin. In six people, the device achieved an average blood glucose level of 140 milligrams per deciliter (mg/dl), which is well within the American Diabetes Association guidelines for care. However, five people absorbed the insulin much slower than expected, and ended up with low blood sugar levels serious enough to require intervention with additional food.
The researchers were surprised by the significant difference in blood sugar absorption rates, but went back and adjusted the mathematical formulation, and retested the device in a second experiment. This time, they achieved an average blood glucose level of 164 mg/dl, which is slightly higher than the ADA's goal
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