July 30, 2001 -- A naturally occurring hormone appears to burn fat in muscle cells and help reverse insulin resistance, according to two new studies. The properties of this hormone -- called adiponectin -- could eventually lead to new treatments for insulin resistance, diabetes, and obesity, says researchers.
People with those conditions have been shown to have lower-than-normal levels of adiponectin, according to Philipp Scherer, PhD, author of one of the studies.
Accumulation of fat in muscle cells is known to be strongly associated with insulin resistance, a condition that occurs when the body does not properly respond to insulin, a hormone that regulates how the body uses sugar, explains Alan Saltiel, PhD.
"The therapeutic uses of [adiponectin] are not really clear at this early date, but it's not a great leap to say that people would like to be able to burn fat," says Saltiel, professor of medicine at the University of Michigan Life Sciences Institute, in Ann Arbor, and author of an editorial accompanying the two reports in the August 1 issue of Nature Medicine.
One study, from the University of Tokyo, found that when insulin-resistant mice were injected with adiponectin, their levels of blood sugar were lowered. Even more important, the hormone decreased levels of fatty triglycerides in certain muscles.
The success with the injection therapy led authors Takashi Kadowaki, MD, and colleagues to suggest that adiponectin supplementation might be a viable way to treat insulin resistance and type 2 diabetes.
A second report found that the hormone, when injected in obese and diabetic mice, led to a significant decrease in blood sugar levels without increasing insulin, according to Scherer, of Albert Einstein College of Medicine, in New York.
That raises the question: How is the hormone decreasing blood sugar while not affecting insulin levels?
Scherer suggests that adiponectin acts as an insulin "sensitizer," making cells more responsive to insulin, so that only a little insulin is needed to control blood sugar levels.
Therefore, adiponectin may be crucial in the overall way the body regulates the intake and use of food and energy, he says. "We think of this protein as a policeman directing traffic," he tells WebMD.
The findings hold out promise for patients with insulin resistance, type 2 diabetes, and obesity, says Saltiel. Such good news is needed, given the relatively poor quality of therapies available for these conditions.
"Our current therapies for obesity are pathetic," he says. "Our treatments for diabetes are OK but could be better," he says.