Workplace bullying and violence 'risk factors' for type 2 diabetes

"Workplace bullying increases risk of type 2 diabetes by 46%, study finds," reports the Mail Online.

A new study looked at data from 4 different Nordic research projects to investigate whether employees exposed to workplace bullying and violence at work are at increased risk of developing type 2 diabetes.

A distinction was made between workplace bullying and violence (or threats of violence) at work because bullying can take many forms. Also, some professionals, such as police or prison officers, usually have training designed to help them cope better with violence at work.

The study found that people who said they'd experienced workplace bullying or violence had an increased risk of developing type 2 diabetes compared with those who didn't report any bullying or violence.

These are interesting findings with a number of potential explanations. Stress, caused by bullying or violence, can have a wide range of potential effects. For example, it can lead to comfort eating and spending longer sitting still at your desk, which can cause weight gain. Being overweight is a risk factor for type 2 diabetes.

Of course, regardless of the potential link to an increased risk of diabetes, workplace bullying and violence shouldn't be ignored. The GOV.UK website provides more advice about what to do if you feel you're being bullied or harassed at work.

Where did the story come from?

The study was carried out by a team of researchers from Denmark, Sweden, Finland, the UK and China. It was funded by a number of Nordic research institutions, including NordForsk, the Nordic Programme on Health and Welfare, the Project on Psychosocial Work Environment and Healthy Ageing , and the Danish Working Environment Foundation.

The study was published in the peer-reviewed medical journal Diabetologia on an open-access basis and can be viewed for free online.

The Mail Online's reporting had a number of inaccuracies. Its headline implied that a cause-and-effect relationship between bullying, violence and diabetes had been proven, which isn't the case.

It also claimed that 20% of all US workers report bullying at work. The 20% figure actually related to nurses who reported exposure to violence or threats of violence at work, which is not the same thing as bullying.

What kind of research was this?

This was an analysis of data from 4 cohort studies that aimed to investigate whether employees exposed to workplace bullying and violence are at increased risk of developing type 2 diabetes.

Previous research has indicated that some aspects of work, such as job insecurity and long working hours, are moderately associated with an increased risk of diabetes. However, there is far less literature on the link between social stress factors in the workplace, such as bullying and violence, and diabetes.

Observational studies like this one are useful for suggesting a potential link between exposure and outcome. But they can't fully rule out other factors that might play a role in any link found.

What did the research involve?

The group of participants was derived from 4 prospective cohort studies:

• the Swedish Work Environment Survey (SWES)
• the Swedish Longitudinal Occupational Survey of Health (SLOSH)
• the Finnish Public Sector Study (FPSS)
• the Danish Work Environment Cohort Study (DWECS)

The final study population included 26,625 women and 19,280 men. All participants were aged between 40 and 65, and hadn't been previously diagnosed with diabetes. Workplace bullying and violence were measured using questionnaires.

In the observational study, workplace bullying was described as "persistent, repeated harassing, offending and socially excluding behaviours of psychological nature over a long period". In 3 of the 4 cohort studies, it was defined as having been bullied in the workplace at least once in the previous 12 months. In the FPSS, the participants were asked whether they were currently being bullied.

Workplace violence was measured in 3 of the studies as the "experience of having been the target of violent actions or threats of violence in the past 12 months at the workplace". It wasn't measured in the FPSS, so this study wasn't included in the workplace violence analysis.

The development of type 2 diabetes in the study population was tracked using nationwide health registers in Sweden, Finland and Denmark.

Researchers pooled the studies to look at the association between the onset of type 2 diabetes and workplace bullying or violence. Analyses were adjusted for the potential confounders of age, sex, country of birth, educational level and marital status.

What were the basic results?

Workplace bullying

Across the 4 cohorts, 9% of the participants (just over 4,000 people) reported being exposed to bullying in the workplace. There were 1,223 new diagnoses of type 2 diabetes during an average 11.7-year follow-up.

Following adjustment, participants who reported any experience of bullying in the previous 12 months were found to have a higher risk of developing type 2 diabetes than those who reported no bullying (hazard ratio [HR] 1.46, 95% confidence interval [CI] 1.23 to 1.74).

Workplace violence

Three cohorts were assessed for this analysis, and 12% of these participants reported having been exposed to workplace violence. There were 930 new cases of type 2 diabetes in these 3 studies during an average 11.4-year follow-up.

Again, following adjustment, threats of violence or experiences of violence in the workplace were associated with a higher risk of developing type 2 diabetes (HR 1.26, 95% CI 1.02 to 1.56) compared with no report of violence.

How did the researchers interpret the results?

The researchers wrote: "In conclusion, we have shown a moderate and robust association between workplace bullying and violence and the development of type 2 diabetes. Both bullying and violence or threats of violence are common in the workplace.

"Research on bullying and violence prevention policies with workplaces as the target are warranted to determine whether these policies could be effective means of reducing the incidence of type 2 diabetes."

Conclusion

This analysis of data from 4 large Nordic cohort studies has found some link between employees being exposed to workplace bullying or violence (or threats of violence) and risk of developing type 2 diabetes. This may seem unusual, but the study authors highlight a few plausible mechanisms:

• Bullying could lead to stress-related coping strategies, such as comfort eating.
• Stress at work could lead to longer working hours, and thus an increase in sedentary behaviour and, potentially, less time for individuals to exercise.
• Spending longer at work could also result in having less time to prepare healthy meals for lunch and dinner, and people might instead reach for convenience foods.

All of these things could contribute to putting on weight or developing a larger waistline, both of which are independent risk factors for type 2 diabetes.

However, the study also had several limitations:

• Most notably, workplace bullying and violence was self-reported, and these experiences are highly subjective. There could be potential for under- or over-reporting. Therefore, the study may not be a completely accurate record of people who are bullied at work.
• Exposure to bullying and violence was only measured at the start of the study, so any changes in bullying or violence in the workplace and the effects of any such change couldn't be taken into account.
• Only between 2% and 3% of the cohort developed diabetes, meaning the baseline risk was low. Even if bullying did increase the risk, it would be a 46% increase on 2%, which means an absolute increase of 0.92%. So the individual's risk is still likely to remain low.
• The sample populations from the Nordic countries involved may not be representative of other countries.

The researchers highlight that, at this stage, the results should be interpreted with caution. Further study of any possible links between stress and type 2 diabetes is needed.

Of course, regardless of the potential to increase the risk of diabetes, workplace bullying and violence shouldn't be ignored. Anyone who feels threatened or harassed at work should report it. A good first step is to talk to your manger, HR department or trade union representative.

Read more advice about workplace bullying and harassment.