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People who secrete low melatonin levels during sleep may be at a higher risk of developing type 2 diabetes.

While millions of people around the world live with the type 2 diabetes, scientists are still unsure about the exact causes of the metabolic disease in which the body does not produce enough insulin.

However, researchers from Brigham and Women's Hospital (BWH) may have found a new risk factor for diabetes after they found a link between low nocturnal melatonin secretion levels with an increased risk of developing type 2 diabetes.

Researchers say the findings published in the April 3 issue of JAMA suggests that the amount of melatonin a person secretes during sleep may predict their risk of developing type 2 diabetes.

The hormone melatonin is produced by the pineal gland located in the center of the brain and is secreted into a person's bloodstream. The hormone is mainly produced at night, when it levels peak in the bloodstream allowing regulation of the circadian rhythm.

Dr. Ciaran McMullan, a researcher in the Renal Division and Kidney Clinical Research Institute at BWH, and her team used data from the Nurses' Health Study and identified 370 women who developed diabetes and 370 control subjects of the same age and race.  Researchers compared the two groups and found participants with low levels of nocturnal melatonin secretion had about two times the risk of developing type 2 diabetes compared to participants with high levels of nocturnal melatonin secretion.  Researchers said even after accounting for other well-established diabetes risk factors, such as body mass index, family history of diabetes and lifestyle factors including diet, exercise, smoking and sleep duration, melatonin secretion still remained a significant risk factor in predicting the development of the metabolic disease.

"This is the first time that an independent association has been established between nocturnal melatonin secretion and type 2 diabetes risk," McMullan said in a statement. "Hopefully this study will prompt future research to examine what influences a person's melatonin secretion and what is melatonin's role in altering a person's glucose metabolism and risk of diabetes."