Night-Shift Work May Impair Glucose Tolerance

Working the night shift may reduce glucose tolerance and increase a person’s risk of developing Type 2 diabetes, according to a new study from researchers in Boston. Nearly 24 million people in the United States have Type 2 diabetes, and roughly 8.6 million Americans work the night shift.


Previous studies have shown that people who work the night shift have an increased risk of developing Type 2. To determine what factors might contribute to this increase in risk, researchers recruited 13 healthy, nonobese adults who did not have a significant history of night-shift work. The participants were assigned to complete two eight-day procedures in the laboratory in random order. Both procedures included four baseline days, which were then followed by either four days of daytime work or four days of nighttime work.

The content of meals provided to both groups was identical; however, people working the day shift began eating at 8 AM, while people working the night shift began eating at 8 PM. Participants had a fasting blood sample taken before the meal, with additional samples taken every 10 minutes for 90 minutes following the meal and every 30 minutes for 90 minutes thereafter.

The researchers found that peak blood glucose levels were 16% higher during the nighttime shifts compared to during the daytime shifts. They also discovered that, although the meals given to each group were identical, the insulin levels in the night-shift workers were 40% to 50% higher between 80 and 90 minutes after their meal than the insulin levels in daytime workers during the same time frame.

“It is surprising that just a single night shift can significantly impair glucose tolerance and increase insulin levels. 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 2 diabetes,” noted lead author Christopher Morris, PhD.

For more information, read the article “Night Work May Impair Glucose Tolerance” or download a copy of the journal SLEEP’s abstract supplement and view the study abstract on page A182. And to learn more about getting the sleep you need, read this piece by nurse David Spero.

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  • Joe

    Interesting, but what can we do about it? We’re not likely to go back to a world where everyone worked sun-to-sun, and every business closed at 5:00 PM. Would night-shift induced diabetics ever qualify for work-related disability? We’re looking at millions of people. If this were some other disease we might be talking about changing labor laws and compensating victims, but due to the rampant prejudice against type 2 diabetics, I doubt we’ll ever see anything like that.

  • Susan

    I work for Postal Service, the mail mainly moves at night to be delivered in morning. I don’t have a choice and totally agree with this study and the previous comment from Joe. I don’t know what to do, everyday is different when it comes to my sleep or the way I feel. I wish I could retire!!

  • ron

    i was diagnosed with type 2 after working 23 years of rotating shifts. 2 of my fellow employees were also diagnosed in that time frame.

  • Jill Erramouspe

    This is really interesting for me. Off and on over my work life, I worked in situations where I worked night shift (midnight to 8 am) several times. At one point, I worked this shift for one year straight. I was not diagnosed with type 2 diabetes for some years after that. I did have a baby over 9 lbs, which is another risk factor for type 2 diabetes.

    My daughter had gestational diabetes with her second child, and after about a year ended up with type 1 diabetes. She now wears an insulin pump.

    I developed type 2 diabetes about seven years ago, and after a few years my pancreas stopped producing insulin. I now also wear an insulin pump, which controls my blood sugar fairly well. I guess I could do better, if I would watch my diet and exercise more.

    It is really interesting that my past work might be a contributing factor to my current diabetes.

  • Ron Keys

    How does one develop these ailments working night shift? Is it due to a poor diet or is it just working night shift in general?