Shift Work Linked To Increased Risk Of Type 2 Diabetes

Robert Glatter | July 25, 2014.

Type 2 diabetes is more common in those who work shifts, according to results of a new study.

Data from the study adds to the ongoing concern for those who work shifts, in which known risks already include cancer, digestive diseases, and cardiovascular disease.

Findings of the study were reported July 24 in the Journal, Occupational and Environmental Medicine.

“Physicians have long been aware that sleep is a critical part of our health,” explained Dr. Alan Manevitz, Clinical Psychiatrist at Lenox Hill Hospital in New York City.  “So a new study linking shift work – in which 10 million Americans take part – to type 2 diabetes is not ‘new news’.”

“Since diabetes itself is caused by a combination of genetic and lifestyle factors, including sleep, the results make sense,” added Manevitz.

It is believed that disruption of sleep patterns leading to lack of sleep triggers metabolic and hormonal changes leading to increase in appetite, and subsequent weight gain.

In fact, results of previous sleep studies in laboratory settings have already demonstrated that when people sleep during daylight hours they can develop early stages of type 2 diabetes within a few weeks.

The study, a meta-analysis, evaluating over 226,000 persons, provides an even stronger association between altered sleep patterns and development of type 2 diabetes.

Data from the study, from the Huazhong University of Science and Technology in China showed that overall, shift workers were 9 percent more likely to have type 2 diabetes. In men, the risk rose to 35 percent and in those who rotated between day and night shifts, the risk was even higher—42 percent.

The authors write, “Given the increasing prevalence of shift work worldwide, and the heavy economic burden of diabetes, the results of out study provide practical and valuable clues for the prevention of diabetes.” With the addition that “male shift workers should pay more attention to the prevention of diabetes.”

The reason for increase risk for type 2 diabetes is likely related to altered sleeping and eating patterns as a result of shift work. One explanation is that eating late at night makes one more likely to store the calories as fat, leading to an increase risk for development of obesity, and consequently type 2 diabetes.

Another explanation is that the daytime levels of the male hormone, testosterone, are controlled by the circadian rhythm, essentially the body’s internal clock. Shift work seems to affect the clock, leading to lower testosterone levels, which are ultimately linked to insulin resistance and development of diabetes.

However, other factors beside testosterone may also be at work.

“Study authors implicate the disruption of the male hormone testosterone as one potential trigger of insulin resistance and diabetes in study participants,” Manevitz explains, “but a wide array of other body chemicals are also skewed when normal sleep patterns are disrupted, including leptin and growth hormone.”

But another important syndrome predisposing one to diabetes also deserves special mention in the setting of the discussion about diabetes.

“Metabolic syndrome – a cluster of conditions occurring simultaneously that increase the risk for diabetes, among other serious conditions – is three times higher among individuals working the night shift, according to previous research,” said Manevitz.

Potential ways to combat the elevated risk for developing diabetes associated with shift work include eating a healthy and balanced diet, engaging in regular exercise, along with practicing effective sleep hygiene to promote a more conducive environment to falling and staying asleep for longer periods.

“Sound sleep hygiene is paramount for shift workers,” said Manevitz, “including using blackout curtains and a sound machine to block daytime noises.”

“Shift workers should also be diligent about controlling lifestyle factors such as diet and exercise – important to us all, but especially those whose jobs preclude sleeping during normal nighttime hours,” added Manevitz.

Screening shift workers for elevated cholesterol, blood pressure as well as increasing hemoglobin A1C, a sensitive marker for developing diabetes makes good sense in the workplace.  This can spot those at risk for developing type 2 diabetes, before their blood sugar begins to elevate.


Diabetes leads to damage to blood vessels and nerves while increasing the risk for developing coronary artery disease, potentially leading to heart attacks, as well as strokes.

The authors point out that while the study was large, it was observational. As a result, no direct cause and effect relationship can be established.

Projections are that nearly 380 million people will have type 2 diabetes by 2025, making this an urgent public health issue.


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