Body Clock Gene Linked to Diabetes Risk

A gene related to melatonin, a hormone thought to be responsible for humans sleep-wake cycles, has now been linked to diabetes risk. High blood sugar levels were observed through disrupted sleep patterns, due to variations in the gene.

A topic of much research is the presence, or lack thereof, of an “internal body clock.” Most evidence suggests that through various mechanisms, our bodies, and those of most animals, do have natural processes, hormones and genes, that regulate our sleeping habits, and the ability to differentiate daytime from nighttime, without external stimulus (such as sun-light or temperature variance). The hormone melatonin has been closely linked to these processes and abilities, rising at night, and falling during the day.

In the current study, researchers found that a melatonin receptor gene, in addition to being responsible for melatonin’s mechanisms, is also closely linked to blood sugar levels, and risk of developing type 2 diabetes. Professor Mark McCarthy, study researcher, says that “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.”

This evidence came through a study of over 36,000 individuals, some with an observed “variant” of the melatonin receptor gene that was observed to cause disrupted sleep patterns. There were significantly higher fasting blood glucose (prior to food consumption) levels in these individuals (0.07 mmol/l higher), and there was a 9% greater incidence of type 2 diabetes in individuals with the gene variant.

High blood glucose levels don’t always mean increased diabetes risk, especially when it comes to complicated genetics. That makes the 9% observed increase, within a large sampling group, very significant. Researcher Ines Barroso concludes that “we have found a variant – a G in the genome in place of a C – in MTNR1B. This single-letter change influences both sugar levels and diabetes. This remarkable result should allow us to gain new insight into this problem.”

Source: Defeat Diabetes Foundation: Barroso, Ines. McCarthy, Mark. Nature Genetics news release. December 2008.

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