Nanci Hellmich, USA TODAY
A hormone best known for its role in helping people sleep may play a part in someone's risk of developing type 2 diabetes, based on a new study.
The research, out today, shows that people who have low levels of melatonin while they're sleeping are at a greater risk of developing type 2 diabetes.
Melatonin is a hormone produced by the brain mainly at night and then released into the bloodstream. It typically peaks in the body about three to five hours after people go to sleep and regulates their sleep-wake cycles. The nightly increase in melatonin in the blood helps to keep bodily rhythms synchronized. Melatonin is involved in many functions in the body, and some research suggests it affects glucose (sugar) metabolism.
Almost 26 million U.S. adults and children have diabetes. In diabetes, the body does not make enough of the hormone insulin, or it doesn't use it properly. Insulin helps glucose get into cells, where it is used for energy. If there's an insulin problem, sugar builds up in the blood, damaging nerves and blood vessels. There are two major forms: type 1 and type 2. In adults, type 2 diabetes accounts for 90% to 95% of all diagnosed cases.
To investigate the possible association between melatonin and type 2 diabetes, researchers at Brigham and Women's Hospital in Boston examined the blood and urine samples of 370 women who developed type 2 diabetes from 2000 to 2012 and matched them to 370 women of the same race and age who did not develop the disease. All the women were participants in the Nurses' Health Study. The women filled out questionnaires about their physical activity levels, diet, sleep habits, smoking habits and family history of type 2 diabetes.
Findings in the Journal of the American Medical Association: Women with low levels of melatonin at night had twice the risk of developing type 2 diabetes as those with high levels. That was true even after researchers took into account other risk factors for type 2 diabetes, including being overweight or obese, a family history of the disease, diet and smoking.
"It's possible that melatonin impacts the ability of the pancreas to secrete insulin, and the body's sensitivity to insulin, which could lead to type 2 diabetes," says lead author Ciaran McMullan, a research fellow in medicine at Brigham and Women's Hospital.
Studies with rats have shown that feeding them melatonin helps protect against the onset of type 2 diabetes, but that doesn't mean it will work for humans, he says.
"We don't know yet that raising someone's melatonin levels would lower their risk of developing type 2 diabetes," McMullan says. "We cannot make any treatment recommendations on taking melatonin supplements based on this study. "This is an observational study, and randomized trials are needed to confirm our findings."
Sleep researcher Eve Van Cauter, director of the Sleep, Metabolism and Health Center at the University of Chicago, says, "Insufficient sleep, poor sleep quality, including sleep apnea, and irregular sleep-wake cycles such as those that occur in shift work have all been linked to an increased risk of type 2 diabetes.
"Good regular sleep habits and avoiding light exposure in the wee hours will help to produce melatonin and may reduce the risk of developing type 2 diabetes."
Some facts about diabetes:
Almost 26 million children and adults (8.3% of the U.S. population) have diabetes.
18.8 million people are diagnosed; an additional 7 million are undiagnosed.
79 million Americans have pre-diabetes and are at risk for developing type 2 diabetes.
Symptoms of diabetes include thirst, hunger, tiredness, blurry vision, healing problems and frequent urination. However, not all people with diabetes have symptoms. Even if they aren't having symptoms, people who are obese, older or have a family history of diabetes, as well as African Americans, Mexican Americans and American Indians, are at increased risk of developing type 2 diabetes.
About one in three Americans may develop diabetes by 2050 if something isn't done to reverse the trend, government statistics show.
Diabetes may lead to heart disease, stroke, kidney failure, foot and leg amputations and blindness.
Source: Centers for Disease Control and Prevention and the American Diabetes Association