Diabetes-related nerve damage of the feet and legs, called diabetic polyneuropathy, improves after treatment with ghrelin, part of a protein produced in the stomach, a new study finds. The results, from animals and from several diabetic patients, will be presented Sunday at The Endocrine Society’s 92nd Annual Meeting in San Diego.
Ghrelin is perhaps best known as the “hunger hormone” because of its appetite-stimulating role in the body. Its other main purpose is to transiently increase secretion of growth hormone, which builds our muscle and bone mass and decreases body fat.
People with diabetes have suppressed growth hormone secretion, which is one cause of their metabolic unbalance, said the study’s primary author, Masamitsu Nakazato, MD, PhD, a professor at Japan’s University of Miyazaki.
“Ghrelin is a potential novel therapeutic approach for the treatment of polyneuropathy, an otherwise intractable disorder,” Nakazato said.
Polyneuropathy is the most common long-term complication of diabetes, affecting more than 50 percent of people who have had high blood glucose (blood sugar) at least several years, Nakazato said. It causes burning pain, numbness and eventually lack of ability to feel hot or cold in the feet and legs, and sometimes the hands. People with this condition are more likely to develop diabetic ulcers, or sores, especially on their feet. Muscle weakness also may occur.
In their study, Nakazato and colleagues first studied the effects of intraperitoneal (injection into the body cavity) administration of synthetic ghrelin in mice with chemically induced diabetes. They evaluated nerve injury using the nerve conduction velocities test, which measures the speed of electrical signals through the nerve in response to a mild electrical stimulation. A decreased velocity, or speed, indicates nerve damage.
Ghrelin improved reductions in motor and sensory nerve conduction velocities in the diabetic mice and normalized their temperature sensation, Nakazato said.
The researchers then tested intravenous ghrelin therapy in three men with Type 2 diabetes who were not taking insulin. These men received ghrelin for two weeks after breakfast so that ghrelin would not stimulate food intake, according to Nakazato.
“After ghrelin treatment, all three patients had improved nerve conduction velocity of the lower limbs and improved symptoms of polyneuropathy,” Nakazato said.
Importantly, the patients did not gain any weight or have any worsening of blood sugar as a result of ghrelin, he stated.
The researchers plan to study ghrelin in larger numbers of diabetic individuals, giving the drug through injections under the skin, which would be more convenient for patients.
