Women who worked a rotating night shift had an increased risk of type 2 diabetes that was not completely explained by an increase in body mass index (BMI), according to results of a prospective study of women who were enrolled in the Nurses' Health Studies.  Nurses who had 1 to 10 years of night shift work  saw a 5% excess risk for type 2 diabetes compared to women who did minimal to no night shift work. That risk climbed to 40% after a decade of shift work, according to Frank Hu, MD, PhD, from Brigham and Women's Hospital/Harvard School of Medicine in Boston, and colleagues.

Excess risk rocketed to almost 60% for those who had put in 20 years or more, the group reported. Other studies have suggested that rotating night shift work is associated with an increased risk for obesity and metabolic syndrome, both of which are conditions related to type 2 diabetes, they wrote.

Hu's group examined the relationship between the duration of rotating night shift work and the risk of type 2 diabetes in U.S. women who participated in Nurses' Health Studies (NHS) I and II. They also looked at whether greater weight gain was linked to duration of shift work.

Collectively, NHS I and II enrolled nearly 240,000 women. For this study, the women who completed the NHS questionnaire in 1988 or 1989 served as the baseline for this particular study. Participants were excluded if they had diabetes, heart disease, stroke, or cancer at baseline. Follow-up took place at 18 to 20 years.

Rotating night shifts were defined as working at least three nights a month in addition to days and evenings in that same month. The control group consisted of women who did not report a history of rotating night shift work.  In both cohorts, women who spent more years in night shift work were older, more likely to have a higher BMI, and be smokers.

In a secondary analysis, they found that night shift work was also associated with an elevated risk for obesity and excessive weight gain during the follow-up period.   They suggested that, beyond BMI, a reason for the link between shift work and type 2 diabetes may be "chronic misalignment between the endogenous circadian timing system and the behavior cycles." This misalignment has been pegged as a reason for metabolic and cardiovascular disorders, including increases in glucose and insulin, they wrote.

In an accompanying commentary, Mika Kivimäki, PhD, from University College London, and colleagues said the study "probably represents the most accurate estimate of shift work-type 2 diabetes association available to date, suggesting this effect is comparable in size to that of work stress in coronary heart disease and larger than the effect of work stress on type 2 diabetes."

They suggested that in an increasingly "24/7" society, efforts need to be made to prevent type 2 diabetes among shift workers by promoting healthy lifestyle and weight control. Also, prediabetic and diabetic employees need to be identified early and treated accordingly.
Source reference:
Hu FB, et al  PLoS Medicine 2011; 8(12).

 

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Comments

I dont think its actually shift work that causes diabetes but the life style that comes with it, as you say many smoke, but in addition to this for many of us the diet around unsociable hours is poor with the only available options such as vending machines or cafe foods.

I have been a shift worker for around 10 years now, and my company has always advocated healthy lifestyles by offering subsidized gym membership and healthy eating options at all hours, and so far none of us have any signs of diabetes.

I wonder what implications this has for the population at large. Many industries have a large number of overnight workers. Does this disproportionately affect women over men?

I been searching this information for a while. After an hours of continuous Googleing, at last I received it within your website. I wonder what is the Google's problem that does not rank this kind of informative web sites closer to the superior. Normally the most notable sites are rich in garbage.

Good to see such work being undertaken to get a greater understanding of the risk profiles for people who may contract diabetes. Can you tell me if you think this particular increase in risk is gender specific?
Even if not gender specific is the rate of increased risk the same for men or is it above or below that of women?

I've always thought shift work created an unhealthy lifestyle and am not surprised to see that your post provides data supporting that. Since it's not an option for many, those affected can only recognize the risks and try to minimize the effects as best as possible. Great post!

Though the causation of the evidence has to be independently verified by scientific community,these things have to be incorporated while forming worker's right guidelines so as to minimize the change of shifts.Like,there should be a rule limiting maximum number shift change in a year.

Out of curiosity, are those numbers quoted in the study pertaining to the odds ratio?

EDITOR'S REPLY: This article talks about increase risk in a percentage. For example, if the risk is 1 in 100, a 50% increase in risk would make it 2 in 100. The percentage applies to the first number.

Good post but I was wondering if you could write a litte more on this topic? I'd be very grateful if you could elaborate a little bit more. Thank you!

Because I have a personal interest in diabetes (primarily because of my dad, and also because I'm beginning to think I'm pre-diabetic) - I have to wonder another thing, not entirely related to the "rotating night shift" info.

In my line of work, I don't work nights (per se, although I do work AT night on occasion) -but I sit in front of a computer all day, and find myself in that old saying: "A body in motion tends to stay in motion, but a body at rest tends to stay at rest."

So, my point is: What if the people working these night shifts are just dealing with changes that are not supporting "normal" activities that day-shift workers are involved in?

For example, the mom who works nights gets home to a household of kids getting off to school. She cleans up the morning kitchen, and then, exhausted, falls into bed. No working out, no real "fun" or "life" that most people enjoy in a day job.

What would happen? Well, the same (I think) that happens to someone who is glued behind a desk all day and then has to hustle to get the family ready for the evening, etc.

In other words - just kind of a "screwed up" schedule that may not make it easy to become "a body in motion."

Personally, I'm really working to combat that, and FORCE myself into some activity each day with the hope that it will bring my weight and BMI back into the range where it belongs...

Anyway, sorry to ramble on like this, but I can't help but wonder whether it's so much the night shift as it is simply a matter of being overwhelmed and unable to find ways to "fit" a healthier lifestyle into a "non-normal" lifestyle.

Just some thoughts... Thanks! Kate

Shift working is perhaps synonymous with stress and sleep deprivation. It probably also makes it harder to maintain a healthy diet and eating pattern.

These factors are likely to elevate cortisol levels, which in turn increases insulin resistance and could lead to diabetes.

Can you have hyperglycemia without having diabetes?
I went to an internal medicine doctor, who found out that I am slightly anemic and I have hyperglycemia (borderline). I don't know what the borderline thing means. My paternal grandfather had type I diabetes, most other women and men in the upper ages 50 and over have type II diabetes. I am always thirsty (even at night when i'm asleep), urination, I get really really really irritated if I haven't eaten anything and I feel extremely weak and tired if I haven't eaten.
Now, from what I read, you have to have diabetes to have hyperglycemia. But I don't. I've never been in a diabetic coma or anything. Should I go back to a doctor? No insurance right now, so I'm trying to think about everything b4 I walk in there ya know.

Hi
This is an interesting topic, and the findings are very relevant. It makes sense that our natural metabolism should be disturbed with the changes in eating times.

I have worked night shifts many times and found that I tended to eat more junk foods and sugars just to stay awake and keep alert in the "small hours". This alone could increase the chances of suffering from diabetes two.

Having worked shifts, in particular night shifts, it's no surprise that it has a detrimental effect on the human body.

With the body clock confused, it throws out knowing when you should be eating and consequently has a knock-on effect on what you are eating.

I think that working during the night means that these women have to spend the day sleeping, the majority of them can not have practise an sport or activity and they can not have a normal diet.

I find all the information useful,I have been looking for site like this.Thanks you have done a good job,it worth bookmarkig.

Wow. This is a really interesting piece. Several members of my family suffer from diabetes and have worked shifts in the past, however I agree that it may not be the work itself that causes it, but the lifestyle associated with it

I started helping my friend out in his shop as he was short staffed and having problems, about three months later I started to really notice symptoms symptomatic with diabetes. Although I can't say it was the fault of the shift work, I do think it has a major bearing on my current condition.

I been searching this information for a while. After an hours of continuous Googleing, at last I received it within your website. I wonder what is the Google’s problem that does not rank this kind of informative web sites closer to the superior. Normally the most notable sites are rich in garbage.

Brilliant Posting!! this is really an interesting post.. and all the women must read this and should get the fact of night shift working......
Thanks for the information you have given in this post!

its nice to see a lot of articles are being written on women health
I found this very helpful

It would be interesting to learn more about whether, this increased risk, is indeed related to the messed up sleep rthyms , or the habits and lifestyles that go with working rotating shifts that include regular night shifts, , or (likely) some percentage of both..
I would also be interested to know the answer to question number one in this thread, that is Does this disproportionately affect women over men?

Anyhow I am always looking for more info, so thanks for an informative article!
Vera

I started helping my friend out in his shop as he was short staffed and having problems, about three months later I started to really notice symptoms symptomatic with diabetes. Although I can’t say it was the fault of the shift work, I do think it has a major bearing on my current condition.

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