A large international study suggests that type 2 diabetes is more common in people who work shifts.
The findings, published in Occupational and Environmental Medicine, indicated men and those doing rotating shifts were at highest risk.
It is thought that disruption to the body clock affects waistlines, hormones and sleep – which could increase the risk.
Type 2 diabetes can lead to blindness, increase the risk of heart attacks and strokes, as well as damaging nerves and blood vessels – dramatically increasing the risk of a foot needing to be amputated.
Studies in a sleep laboratories have shown that making people snooze at the wrong time of day led to the early stages of type 2 diabetes developing within weeks.
Now an analysis of data from 226,652 people strengthens the link with type 2 diabetes.
The study, by researchers at Huazhong University of Science and Technology in China, showed shift workers were 9% more likely to have type 2 diabetes.
But in men, the figure was 35%. For people chopping and changing between day and night shifts, the risk increased by 42%.
The researchers said: “The result suggests that male shift workers should pay more attention to the prevention of diabetes.
“Given the increasing prevalence of shift work worldwide and the heavy economic burden of diabetes, the results of our study provide practical and valuable clues for the prevention of diabetes.”
Possible explanations include shift work disrupting sleeping and eating patterns. One idea is that eating late at night makes the body more prone to store the energy as fat, increasing the risk of obesity and in turn type 2 diabetes.
The increased risk in men could be down to changes in levels of male hormones, it has been suggested.
Also, because the studies are looking at only one snapshot in time it is impossible to say definitively that shift work causes diabetes as other factors could be at play.
The type of person more prone to type 2 diabetes may be more likely to become a shift worker.
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