Diabetes sufferers who must take insulin could be cured by eliminating the actions of a specific hormone, converting their Type 1 diabetes into an asymptomatic, non-insulin-dependent disorder.
The new findings by UT Southwestern Medical Center have so far only been tested on mice. They show that in mice, insulin becomes completely superfluous and its absence does not cause diabetes or any other abnormality when the actions of glucagon are suppressed. Glucagon, a hormone produced by the pancreas, prevents low blood sugar levels in healthy individuals. It causes high blood sugar in people with type 1 diabetes.
“We’ve all been brought up to think insulin is the all-powerful hormone without which life is impossible, but that isn’t the case,” said Dr. Roger Unger, professor of internal medicine and senior author of the study appearing online and in the February issue of Diabetes. “If diabetes is defined as restoration of glucose homeostasis to normal, then this treatment can perhaps be considered very close to a ‘cure.’ ”
The one million sufferers of Type 1 diabetes in the U.S. are insulin dependent. They must take insulin multiple times a day to metabolize blood sugar, regulate blood-sugar levels and prevent diabetic coma. They also must adhere to strict dietary restrictions. This has been the treatment for the disease since its discovery in 1922. But even optimal regulation of type 1 diabetes with insulin alone cannot restore normal glucose tolerance. These new findings demonstrate that the elimination of glucagon action restores glucose tolerance to normal.
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 directs the body’s cells to remove sugar from the bloodstream.
“These findings suggest that if there is no glucagon, it doesn’t matter if you don’t have insulin,” said Dr. Unger, who is also a physician at the Dallas VA Medical Center. “This does not mean insulin is unimportant. It is essential for normal growth and development from neonatal to adulthood. But in adulthood, at least with respect to glucose metabolism, the role of insulin is to control glucagon.
“And if you don’t have glucagon, then you don’t need insulin.”
