-- Mary Elizabeth Dallas
THURSDAY, July 24, 2014 (HealthDay News) -- Shift workers,
especially men, may be at higher risk for type 2 diabetes compared
to people not on such schedules, a new study suggests.
Also at special risk are shift workers who don't work on a set
schedule, with shifts moving around at various times of the
The findings are "not at all surprising," said one expert, Dr.
Alan Manevitz, a clinical psychiatrist at Lenox Hill Hospital in
New York City.
"Physicians have long known that working shifts disrupts many key body chemicals, creating a ripple effect that can lead to ailments such as gastrointestinal disorders, cardiovascular disease and even cancer," he said. "Now type 2 diabetes can be added to this considerable list."
In the new review, researchers analyzed data from 12
international studies involving more than 226,500 people.
The study, led by Zuxun Lu of Huazhong University of Science and
Technology in Wuhan, China, took several factors into account, such
as workers' shift schedules, their body mass index (BMI, a
calculation of height and weight), family history of diabetes and
their level of physical activity.
Although the findings weren't able to show a direct
cause-and-effect relationship, the researchers found that any
amount of shift work was linked to a 9 percent greater risk for
developing diabetes. Gender also played a role -- for men engaged
in shift work, the risk jumped to 37 percent.
Although the reason why men are at greater risk than women isn't
clear, the researchers believe that testosterone levels may play a
role. Prior studies have pointed to an association between low
testosterone levels and insulin resistance and diabetes, the
Daytime levels of this male hormone are regulated by the
internal body clock, Lu's team explained.
Those whose shifts moved around through different periods of the
day were especially likely to develop type 2 diabetes than those
who worked normal "office hours." The study found rotating shift
work to be linked to a 42 percent greater risk for diabetes.
According to Lu's team, erratic working schedules make it more
difficult for the body to establish a sleep-wake cycle, and poor
sleep may worsen insulin resistance, a precursor to diabetes.
Previous studies have also linked shift work to weight gain and
obesity, a big risk factor for type 2 diabetes. And the researchers
note that shift work can also affect cholesterol levels and blood
Another expert said other factors may be at play as well.
"Growth hormone, known to elevate blood glucose when present in excess, peaks at 1 a.m.," noted Dr. Gerald Bernstein, director of the Diabetes Management Program at Friedman Diabetes Institute at the Beth Israel Medical Center in New York City. "Shift work also often makes it more difficult to schedule regular meals and exercise."
Still, Bernstein said that "even with a strong risk for diabetes
I would not discourage someone from taking a job that is based on
Instead, he said "it would be better to screen shift workers
regularly for pre-diabetes and intervene to slow the progression to
Manevitz agreed. "Those who must do shift work would be wise to
consult their doctor, who can monitor cholesterol levels, blood
pressure and insulin levels to detect if blood sugar levels are
creeping up dangerously," he said. "Doctors may also be able to
prescribe sleep aids to help shift workers get the proper amount of
sleep, even if that sleep comes during odd hours."
The study was published recently in
Occupational & Environmental Medicine.
The American Psychological Association provides more information
health effects of shift work.
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