Shift workers – particularly male shift workers – may be at greater risk of type 2 diabetes, according to a new meta-analysis.

By the year 2025, the number of cases of type 2 diabetes is estimated to increase by 65%, with the condition affecting a projected total of 380 million individuals worldwide. Therefore, identifying modifiable risk factors is of significant public health importance.

Share on Pinterest People who work rotating shifts have a 42% increased risk for type 2 diabetes, according to the meta-analysis.

Previously, studies have examined how shift work – irregular or unusual work schedules, such as working a combination of nights and days – might be associated with an increased risk for diabetes, but results have been inconsistent.

The new meta-analysis – conducted by researchers at Huazhong University of Science and Technology in China – compared the results of 12 international studies, involving more than 226,500 participants, 14,600 of whom had diabetes.

The researchers found that, compared with working normal office hours, any period of shift work is associated with a 9% increased risk of developing diabetes.

Looking more closely at the effects of gender, study design, study location, job, shift schedule, body mass index (BMI), family history of diabetes and physical activity levels, the researchers calculated the increased risk rose to 37% in men.

Although the authors are not certain about why the risk in men is so much higher than in women, they suggest that repeated disruption of the internal body clock may affect levels of the hormone testosterone in men. Previous research has shown that low levels of male hormones are associated with insulin resistance and diabetes.