Shift work has long been linked to an increased risk of type 2 diabetes, with weight gain and poor sleep quality among the outcomes of shift work which can encourage unhealthy habits such as eating at irregular hours and getting less exercise.
In this new study from scientists at Brigham and Women’s Hospital, based in Boston, Massachusetts, US, the impact of shift work was examined to see if it modified the relationship between genetic risk for type 2 diabetes and existing type 2 diabetes.
The researchers reviewed the impact of shift work on 270,000 people, with records taken from the UK Biobank database. The data included employment histories of 70,000 people and genetic data on 44,000 people. More than 6,000 in the sample population had type 2 diabetes.
Using information on more than 100 genetic variants associated with type 2 diabetes, the study team then developed a genetic risk score for type 2 diabetes, examining data from tens of thousands of workers.
Dr Céline Vetter, who co-led the study, explained: “We see a dose-response relationship between frequency of night shift work and type 2 diabetes, where the more often people do shift work, the greater their likelihood of having (type 2 diabetes), regardless of genetic predisposition. This helps us understand one piece of the puzzle: frequency of night shift work seems to be an important factor.”
All shift workers were more likely to have type 2 diabetes except for permanent night workers and permanent day workers. Those who worked irregular or rotating shifts had a 44% increased risk of developing type 2 diabetes.
Because shift work did not affect this probability, researchers now want to investigate this link further.
Fellow researcher Dr Frank Scheer said: “Our finding that there does not seem to be an interaction between those two type 2 diabetes risk factors is novel, and requires replication in future studies, especially in other populations of non-European ancestry.”
The study was published in the journal Diabetes Care.