Night shift workers have impaired glucose tolerance, which makes them more susceptible to type II diabetes, a new study claims.

Researchers published the abstract of their findings recently in the journal SLEEP's abstract supplement and detailed how glucose levels were at its peak during night shifts compared to day shifts.

"It is surprising that just a single night shift can significantly impair glucose tolerance and increase insulin levels," said Christopher Morris, lead author and postdoctoral research fellow in the Medical Chronobiology Program of the Division of Sleep Medicine at Brigham & Women's Hospital and Harvard Medical School in Boston. "These findings are important because they demonstrate, under highly-controlled lab conditions, that acute exposure to night work impairs glucose tolerance. Chronic impaired glucose tolerance is likely to lead to Type II diabetes."

Morris and his team recruited 13 healthy, non-obese adults with no prior work shift-related health history, and had them randomly complete two, eight-day procedures in the laboratory, where one procedure was night work and the other was day work. The first four days for both procedures were baseline, followed by four days of either day shift duty or night shift duty.

They found that peak glucose levels were 16 percent higher during the simulated night shift compared those during simulated daytime work. In addition, when given identical caloric diets, the insulin levels in the night shift workers who ate at 8 p.m. for 20 minutes were 40 to 50 percent higher between 80 minutes and 90 minutes after a meal, compared to dayshift workers who ate at 8 a.m.

The researchers said that nearly 8.6 million Americans work during the night shift. Previous studies have shown that tese nighttime workers, who should be sleeping during their shifts, have created a backward schedule that affects their body's ability to regulate sugars, putting them at risk of developing type II diabetes.

The results will also be presented on June 4 at SLEEP 2013, the 27th annual meeting of the Associated Professional Sleep Societies LLC.

Source: Morris CJ, Yang J, Garcia JI, et al. Simulated night work acutely impairs glucose intolerance. SLEEP. 2013.