Men who works in shift are at higher risk of developing type 2 diabetes, a study warns.
The reasons for this finding are not clear, say the authors, but suggest that men working shift patterns might need to pay more attention to the possible health consequences of their working schedule.
To reach this conclusion, researchers retrieved 12 international studies involving more than 226,500 participants, 14,600 of whom had diabetes.
When they pooled all the results together they calculated that any period of shift work was associated with a 9 percent increased risk of developing diabetes compared with working normal office hours.
This heightened risk rose to 37 percent for men.
"Daytime levels of the male hormone testosterone are controlled by the internal body clock, so it is possible that repeated disruption may affect this," researchers noted, pointing to research implicating low male hormone levels in insulin resistance and diabetes.
Most shift patterns, except mixed and evening shifts, were associated with a heightened risk of the disease compared with those working normal office hours.
And rotating shifts, in which people work different parts of the 24 hour cycle on a regular basis, rather than a fixed pattern, were associated with the highest risk: 42 percent.
Rotating shifts make it harder for people to adjust to a regular sleep-wake cycle, and some research has suggested that a lack of sleep, or poor quality sleep, may prompt or worsen insulin resistance, authors maintained.
The paper was published online in Occupational & Environmental Medicine.
