A Discovery...Is IDDM Really Insulin Dependent?

     The name IDDM surely stands for "Insulin Dependent Diabetes Mellitus," but does the name stop there? Recent research at the UT Southwestern Medical Center says otherwise. Dr. Roger Unger explains, "We've all been brought up to think that insulin is the all-powerful hormone without which life is impossible, but that isn't the case."

     As a brief background, alpha cells produce the hormone glucagon, which increases sugar levels in the blood. This is the opposite function of insulin, which lowers blood-sugar levels by putting the sugar into cells. In IDDM, the insulin is absent, so glucagon levels increase since there is no hormone inhibiting it, and this hormone causes the liver to release large amounts of glucose into the bloodstream.

     Dr. Unger's research showed that by preventing the release of glucagon by alpha cells (stained green in image above), insulin became "unimportant" and glucose tolerance returns to its normal level. Glucose tolerance is the tendency for cells to receive and use glucose. In other words, once this excess amount of glucagon was removed, the liver would no longer pump large amounts of sugar into the blood, and so hyperglycemia could be prevented. If glucose levels become stable, then the presence of insulin is irrelevant, or so his research claims.

     An actually study that the medical center carried out was a test to see the effect of knocking out the gene for producing glucagon, and then knocking out the genes for both glucagon and insulin. The mice that had normal insulin production but lacked glucagon receptors did not contract diabetes and responded normally to the test. Moreover, the mice that were deprived of insulin and glucagon also did not contract diabetes and responded positively to the test. From this study, we can see that whether or not insulin is present, as long as glucagon production is stopped, the organism does not contract diabetes. This test has not been carried out in humans, but there is a chance that it will be in the near future. Dr. Unger says, "The role of insulin is to control glucagon...If we can find a way to block the actions of glucagon in humans, then maybe we can minimize the need for insulin therapy."