Type 2 diabetes is linked with increased risks for blindness, kidney failure, amputation of feet and legs, and even early death. However, while the disease is more associated with risk factors that include weight problems, lack of physical activities and having a family with history of the disease, a new study found a link between shift work and elevated risks for diabetes.
For the new study published in the journal Occupational & Environmental Medicine on July 16, Zuxun Lu from the University of Science and Technology in Wuhan, China, and colleagues examined 12 studies involving 226, 652 participants, nearly 15,000 of whom had diabetes, to evaluate the association between shift work and likelihood of type 2 diabetes.
The researchers found that individuals with shift work schedules were associated with elevated risks for diabetes compared with workers who have normal daytime working schedules.
Lu and colleagues said that the erratic working schedule makes it harder for the body to establish a consistent sleep-wake cycle resulting in poor sleep, which could worsen the body's insulin resistance and lead to the development of diabetes. Earlier research also found an association between shift work and weight gain, and obesity happens to be one of the leading risk factors for diabetes.
"Growth hormone, known to elevate blood glucose when present in excess, peaks at 1 a.m.," said Gerald Bernstein, from the 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."
The overall risk of developing diabetes among shift workers was 9 percent but the risk appears to be higher with men as male shift workers were found to be 37 percent more likely to develop the disease.
"Shift work is associated with an increased risk of DM," Lu and colleagues wrote. "The increase was significantly higher among men and the rotating shift group, which warrants further studies."
Although the reason behind the increased risk for diabetes among male shift workers is not clear, it is believed that daytime levels of the main male sexual hormone testosterone is controlled by the body's internal clock and research suggests an association between low testosterone levels, insulin resistance and diabetes.
The cause and effect association between shift work and elevated risks for type 2 diabetes is not yet conclusive but health experts said that the findings of the study suggest that shift workers should be aware of their risks as well as take precautionary measures such as having healthy diet and engaging in physical activities.
