Some studies have suggested that a longer working week poses an increased risk of type-2 diabetes. 

We thought it might be interesting to take a look at data from different countries around the world, to see if a longer average working week showed any correlation with diabetes prevalence, and potentially supports this theory. Because being overweight is a prominent risk factor for type-2 diabetes, we also looked at overweight prevalence data from these countries, again to see if there was any correlation.

Using OECD and World Health Organisation data for 39 countries, we observed that:

  • overall diabetes prevalence was higher on average in nations with a working week of more than 37.5 hours;
  • in the five countries with the longest working week (Colombia, Turkey, Costa Rica, Mexico and South Africa) the percentage of females who were overweight was higher than the percentage of males who were overweight;
  • but in the majority of countries with a shorter working week (37.5 hours or less) the percentage of males who were overweight was significantly higher than the percentage of females who were overweight;
  • similarly, the percentage of females who were diabetic tended to be higher than the percentage of males who were diabetic in countries with the longest working weeks;
  • and conversely, there was a higher prevalence of diabetic males than diabetic females in countries with shorter working weeks.

Working long hours and diabetes

There are several factors that can increase a person’s risk of developing type-2 diabetes that are not linked to environment or lifestyle. For example, people with a family history of the condition, are over 40 or are of Asian, African or Caribbean ethnic descent, are more likely to develop the condition than other groups.

But in addition to the above, being overweight or obese is a significant risk factor for type-2 diabetes, and there are several aspects of our environment and lifestyle that can have an effect on our BMI. Maintaining an unhealthy diet, high in sugar and saturated fat, not getting enough exercise, excessive alcohol consumption, and poor sleep hygiene can all contribute towards to being overweight or obese.

So how does this relate to the amount of time we spend at work?

‘In theory, there are a number of reasons why someone who continually works longer hours might be more susceptible to obesity and diet-related disease.’ notes Dr Daniel Atkinson, Clinical Director.

An argument can be made that, the longer hours a person works, the less time they will have to make considered food choices or prepare their own food; and the more likely they are to rely on more convenient, typically unhealthy options (for example processed ready meals, takeout, or fast food).

‘If a person’s job involves them being largely sedentary (such as sitting at a desk in an office) then they may also be less physically active overall the more time they spend at work. And if a person tends to frequently work overtime or has a particularly stressful or demanding job, they may ‘comfort eat’, drink alcohol after work more often, sleep less or have lower quality sleep.’

‘But because there are so many possible factors involved in the development of type 2 diabetes, it is difficult for research to draw a definite causal link between the condition and longer average working time.

In 2017, an interesting piece of research into the subject was published in BMJ Diabetes Research and Care. It was an observational study involving over 7,000 participants, whom the researchers followed over 12 years.

It suggested that there was an increased risk of diabetes in women who worked 45 or more hours per week, compared to those who worked 35-40. The same heightened risk was not observed in men who worked longer hours. In fact the data suggested that diabetes incidence actually decreased for men the longer their working week.

The data we observed painted a somewhat similar picture.

Overall diabetes prevalence was generally higher in countries with a longer working week. As demonstrated in the map shown:

  • in countries where the usual hours worked each week was between 37.5 and 39.9, the average diabetes prevalence was 9%;
  • for the 40 to 44.9 hour bracket, the average prevalence was 9.6%,
  • and for 45 hours or more, it was 9.9%

Conversely, the average prevalence was 7.7% in countries where the week consisted of between 35 and 37.4 hours; and 6.1% in countries where the usual working week was 30 to 34.9 hours.

Another observation we made was that in the five countries with the longest working week, diabetic prevalence was higher in females than it was in males. The prevalence of diabetes was also higher in women than in men in the Russian Federation (7th longest working week) and in Chile (9th longest).

Working hours and overweight prevalence

Looking at overall overweight prevalence, there wasn’t a significant trend depending on the length of the working week. However, we did notice a trend when we looked at gender specific data.

  • In the five countries with the longest usual working week (ranging from 43 to 47.7 hours per week), the percentage of women who were overweight was higher than the percentage of men who were overweight.
  • With the exception of South Africa (21.1% difference), the variance was comparatively modest, ranging from 3.4% to 5.2%.
  • At the other end of the table, in the countries with the shortest working week, the percentage of men who were overweight tended to be significantly higher than the percentage of women who were overweight.
  • In the five countries with the shortest working weeks, all of which were situated in Northern or Western Europe, the difference between genders for overweight prevalence ranged from 12.7% to 17.5%.

It’s not possible to draw any concrete conclusions as to why the above may be the case.

A difference between how men and women tend to spend their free time in the countries with shorter working weeks could be a potential factor. For example, it could be the case that men in countries with shorter usual working hours spend more of their free time being sedentary than women.

Differences in culture may likely to be a factor. The workforce in some countries may be more male-orientated, with women performing less paid work but taking on more household duties; whereas in other countries, the workforce may be more evenly split between genders. These differences, and the distribution of family duties in different sex partnerships, might have a knock-on effect on activity levels outside of work.

Exceptions we noticed

South Korea has one of the longest working weeks of the countries we observed (42.2 hours). Diabetes prevalence was at the higher end, but overweight prevalence was much lower in both sexes (32.6% in women and 38.4% in men). Of the countries we looked at, only Japan had a lower overweight prevalence, but had a shorter usual working week (36.6 hours).

People of South East Asian ethnicity are thought to be more susceptible to developing diabetes, which may partly explain why, despite such a lower overweight prevalence, diabetes incidence is comparatively high in South Korea.

The only country where there a was a significantly higher percentage of women who were overweight than there were men was in South Africa, which had the fifth-longest working week (43 hours). The difference in diabetes prevalence between women and men was also the largest.

What do these figures tell us?

Again, as noted by previous research, there isn’t an obvious reason behind these trends. We should also stress that the data presented is simply an observation. There are likely to be a host of reasons why overall diabetes prevalence is higher in some countries than in others, and why the gender balance for being overweight flips beyond a certain threshold.

However, while this data doesn’t really provide any answers, it could contribute towards helping to identify behaviours which increase the risk of diet-related disease (a rising problem in many countries across the world), which in turn could help to highlight where efforts to tackle the problem need to be directed.

These figures don’t paint a concrete picture of why longer working hours may have an adverse effect on diabetes risk,’ Daniel notes, ‘because there are so many environmental and lifestyle factors that can impact upon it. But the correlation does raise some interesting questions around our attitudes to work, how we cope with an increased workload, and moreover what’s expected of us as employees.’

How to prevent a heavy workload affecting your health

It’s important to maintain a healthy relationship between your life in work, and your life outside of it. We’ve written before that preparing your own food to take into work with you is generally healthier than eating out at lunchtime, because you have more control over what goes into what you eat, and you’ll be less likely to make impulse purchases.

As Daniel explains:

If you’re stressed or pressed for time, you’re more likely to comfort eat or make food decisions on the fly, and less likely to be physically active because you feel like you need to spend your spare time resting. In the long term, this can then have an effect on your overall health. But there are measures you can take yourself to lower work-related stress.’

This may be easier for some than others, but once you leave work, try not to look at anything to do with work: be it text messages, emails or chat groups. This will help you to keep your professional and personal life separate, and ensure that stress doesn’t spill over into your own time.

Talk to your manager if your workload is too heavy, or you find yourself staying behind to keep up.

If your job involves you remaining sedentary or stationary for long periods, it’s vital to ensure you’re getting enough physical activity in your own time. This doesn’t have to be on a treadmill at the gym. Exercises like walking and swimming are useful for maintaining a healthy weight, and some might even find that these activities help to alleviate feelings of stress and clear the mind.’

If you’re otherwise concerned about your diet or want to know more about lowering your diabetes risk, your health advisor at your GP surgery may be able to help.