Scientists ID Gene for Insulin Sensitivity

Findings may have implications for diabetes treatment, researcher says

By Mary Elizabeth Dallas

Wednesday, September 12, 2012

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WEDNESDAY, Sept. 12 (HealthDay News) -- Scientists have discovered the single gene that causes insulin sensitivity, which they say might someday help lead to new diabetes treatment.
Insulin sensitivity refers to how well the body uses insulin -- a hormone -- to regulate glucose (sugar) in the blood. The opposite is insulin resistance, which means the body does not use insulin properly.
"Insulin resistance is a major feature of type 2 diabetes. The insulin-producing cells in the pancreas may be working hard and pumping out lots of insulin, but the body's cells no longer respond," study leader Dr. Anna Gloyn, at the Oxford Centre for Diabetes, Endocrinology and Metabolism, explained in an Oxford University news release. "Finding a genetic cause of the opposite -- insulin sensitivity -- gives us a new window on the biological processes involved. Such understanding could be important in developing new drugs that restore insulin sensitivity in type 2 diabetes."
The researchers from Oxford University, the Babraham Institute in Cambridge and the Churchill Hospital in Oxford performed glucose tolerance tests on 15 healthy people and 15 otherwise similar people with Cowden syndrome, a rare condition caused by mutations in the PTEN gene. Cowden syndrome results in benign polyps in the skin, mouth and bowel that increase the risk for breast, thyroid and uterine cancer.
"PTEN is a gene that is heavily involved in processes for both cell growth and metabolism," study first author Dr. Aparna Pal, of the University of Oxford, explained in the news release. "Given PTEN's dual role, we were interested in understanding the metabolic profile of people with Cowden syndrome. It was possible that mutations in PTEN could improve metabolism."
The study revealed the people with Cowden syndrome had significantly higher insulin sensitivity. This was the result of heightened activity in the insulin-signaling pathway, according to the researchers. They added that participants with Cowden syndrome had higher body-mass index scores -- a measure of body fat -- than the others.
After expanding the comparison to more than 2,000 people from an Oxford database, the researchers confirmed that people with Cowden syndrome had more fat and higher rates of obesity.
"This was a surprise. Normally insulin sensitivity goes with being lean," said Professor Fredrik Karpe, who established the Oxford database.
Exercise and a healthy diet remain the best ways to avoid diabetes, the researchers stressed. If left untreated, the disease can lead to heart disease, stroke, nerve damage and blindness.
The study appears in the Sept. 13 issue of the New England Journal of Medicine.

SOURCE: Oxford University, news release, Sept. 12, 2012

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