The sleep hormone melatonin has been linked to a higher risk of diabetes in a US study. It found that women with low levels of melatonin are more than twice as likely to develop type 2 diabetes as women with high levels.
The study suggests that taking a daily supplement that contains melatonin could offer protection against developing diabetes, which is an incurable disorder of the blood.
The research was carried out by the Brigham and Women’s Hospital in Boston and followed on the work of previous studies that had first uncovered an association between levels of melatonin and healthy blood sugar levels. Diabetes is a metabolic disorder in which the body fails to make any or enough insulin to turn sugar from food into glucose for the body’s cells.
The body produces melatonin naturally – it is made by the pineal gland, a pea-shaped organ in the brain that is light sensitive. The hormone is released when it gets dark, signalling to the body that it’s time for sleep. Melatonin supplements are currently prescribed for people who suffer from insomnia.
The Boston study examined blood and urine samples taken from hundreds of women in 2000. By 2012, 370 had been diagnosed with type 2 diabetes. And among those cases there were twice as many women with the lowest levels of melatonin.
Writing in the Journal of the American Medical Association, the researchers revealed that melatonin receptors were found throughout the body, including in pancreatic cells – the pancreas is the organ responsible for producing insulin that turns sugar into glucose. They concluded that there may be a causal role in reduced melatonin levels and the risk of diabetes.
Melatonin is already known to reduce the risk of Parkinson’s disease and to protect cells from age-related damage. The hormone is also found in grape varieties used to make red wine such as Merlot and Cabernet Sauvignon, and in onions, bananas and cherries.
The charity Diabetes UK now wants further research into the potential link between melatonin levels and diabetes.