# Scientists link sleep disorders to Type 2 diabetes



## Lizzie (Dec 8, 2008)

From the Guardian: http://www.guardian.co.uk/science/2008/dec/08/diabetes-sleeping-disorders

Scientists link sleep disorders to diabetes
James Randerson, science correspondent 
The Guardian, Monday December 8 2008 

Scientists have discovered a gene that links type 2 diabetes and sleep disorders, according to a study of more than 36,000 people. The finding, backed by two others published today, suggests a connection between diabetes and the way the body responds to the 24-hour cycle of light and dark.

The new genetic research points to a gene involved in detecting melatonin - a hormone that is part of the body's internal body clock - and an increased risk of diabetes. 

Other genes have previously been linked to high levels of glucose in the blood, but the melatonin receptor is the first gene to be linked to both high blood sugar and increased risk of diabetes.

"We have extremely strong, incontrovertible evidence that the gene encoding melatonin receptor 1B is associated with high fasting glucose levels and increased risk of type 2 diabetes," said Professor Mark McCarthy, of the Oxford Centre for Diabetes, Endocrinology and Metabolism at the University of Oxford.

According to the NHS, type 2 diabetes - frequently associated with obesity - affects approximately 2.3 million people in Britain and at least 500,000 more who are not aware they have the condition. 

The finding, which is published in Nature Genetics, comes from a so-called genome-wide association study. The researchers analysed the genomes of 36,610 people of European descent to look for changes associated with an increased risk of diabetes. They found that a mutation in the MTNR1B gene led to a modest 9% increase in type 2 diabetes risk per copy of the mutated gene present. The large numbers in the study allow the researchers to identify genes which have a small influence on disease. Two other genome-wide association studies in the same journal backed the finding.

The findings will raise the possibility of genetic tests to identify people vulnerable to developing type 2 diabetes. 

Three more large genome-wide association studies published today in Nature Genetics have investigated genes involved in heart disease, insulin levels, blood pressure and cholesterol. Between them they identified 75 genetic changes associated with one of the traits of interest, of which 26 are new to science.

"The power of studies such as ours lies in their ability to examine these traits for early life events, to reflect the genetic makeup of the wider population and to investigate the relationship between genetic variation and environment over time," says Professor Leena Peltonen, head of human genetics at the Wellcome Trust Sanger Institute an author of one of the papers.


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## kojack (Dec 8, 2008)

Good article. As a former researcher (in physics) I always look for the phrase in medical or chemical papers :
vulnerable to developing type 2 diabetes. too often, this is assumed to mean that it is almost certain.
A similar study was done for men and prostate cancer. Many who were tested showed the genetic marker but after many years showed no trace of cancer.


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