A genetic cause of increased sensitivity to the hormone insulin has been identified in new research which could lead to the development of new drug treatments for type 2 diabetes.
“Insulin resistance is a major feature of type 2 diabetes. The insulin-producing cells in the pancreas [beta cells] may be working hard and pumping out lots of insulin, but the body’s cells no longer respond,” study leader Dr. Anna Gloy, of the University of Oxford, explained.
“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 discovery was made by Dr Gloyn and colleagues from Oxford University, the Churchill Hospital in Oxford and the Babraham Institute in Cambridge. The team performed glucose tolerance tests on 15 healthy individuals and 15 patients with Cowden syndrome to examine insulin sensitivity and beta cell function.
Cowden syndrome is a rare condition caused by mutations in the PTEN gene that increase the risk of certain cancers. With PTEN involved in both cell growth and metabolic signalling, the researchers said it was possible that “mutations in PTEN could improve metabolism”.
The results showed that those with Cowden syndrome had significantly lower measures of insulin resistance (i.e. high insulin sensitivity) due to increased activity in the insulin signalling pathway.
After expanding the comparison to more than 2,000 healthy adults from a population-based study, the researchers also surprisingly found higher rates of obesity among the PTEN mutation carriers, despite their low resistance to insulin.
“We have demonstrated an apparently divergent effect of PTEN mutations: increased risks of obesity and cancer but a decreased risk of type 2 diabetes owing to enhanced insulin sensitivity,” first author Dr. Aparna Pal, from the University of Oxford, concluded.
The findings are published in the latest issue of the New England Journal of Medicine .
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