Diabetes breakthrough relies on single injection

A single injection of the hormone leptin proved sufficient to heal terminally ill mice sickened by type 1 diabetes. Leptin lowered blood glucose levels to a normal range and maintained that level for extended periods.

"The fact that these animals don't die and are restored to normal health despite a total lack of insulin is hard for many researchers and clinicians to believe," said Dr. Roger Unger, professor of internal medicine and senior author of the study. "Many scientists, including us, thought it would be a waste of time to give leptin in the absence of insulin. We've been brainwashed into thinking that insulin is the only substance that can correct the consequences of insulin deficiency."

The mechanism of leptin's glucose-lowering action appears to involve the suppression of glucagon, a hormone produced by the pancreas that raises glucose levels. Normally, glucagon is released when the glucose, or sugar, level in the blood is low. In insulin deficiency, however, glucagon levels are inappropriately high and cause the liver to release excessive amounts of glucose into the bloodstream. This action is opposed by insulin, which tells the body's cells to remove sugar from the bloodstream.

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