The study of more than 270,000 people, published online this week in the journal Diabetes Care, also found that the more nights employees work, the greater their odds of having the disease, whether they are genetically predisposed to it or not.
“Shift work, particularly night shifts, disrupts social and biological rhythms, as well as sleep, and has been suggested to increase the risk of metabolic disorders, including Type 2 diabetes,” said co-first author Celine Vetter, director of the Circadian and Sleep Epidemiology Laboratory (CASEL) at CU Boulder. “Our study is one of the first to show a dose-response relationship, where the more often people work nights, the greater their likelihood of having the disease.”
About 15 million Americans work permanent night shifts, rotating shifts or shifts with irregular schedules. Recent studies have found associations between such shift work and cardiovascular disease, diabetes and cancer, but few have looked specifically at how different work schedule characteristics impact risk.