People who sleep late and wake up late could both be at an increased risk of developing diabetes than those who sleep early, according to the study. 

Researchers from Brigham and Women's Hospital in Boston, US, studied the relationship between chronotype (a person's preferred timing of sleep and waking) and diabetes risk and looked at the role of lifestyle factors as well and found it associated with 19 per cent increased risk of diabetes. 

The study, published in the journal Annals of Internal Medicine, analysed the data of 63,676 female nurses. The result shows that around 11 per cent had evening chronotypes, 35 per cent morning, and 54 per cent intermediate. 

Those with evening chronotype had a 72 per cent higher diabetes risk, reducing to 19 per cent when factoring lifestyle. Healthiest lifestyles had only 6 per cent evening chronotypes, while unhealthiest had 25 per cent. 

"When we controlled our unhealthy lifestyle behaviours, the strong association between chronotype and diabetes risk was reduced but still remained, which means that lifestyle factors explain a notable proportion of this association," said first author Sina Kianersi, a postdoctoral research student in the Brigham's Channing Division of Network Medicine.

They also found the association between evening chronotype and diabetes risk only in those nurses who worked day shifts and not those who worked overnight shifts. 

"When chronotype was not matched with work hours we saw an increase in type 2 diabetes risk," said Tianyi Huang, associate epidemiologist at Brigham. 

"That was another very interesting finding suggesting that more personalised work scheduling could be beneficial." 

Meanwhile, researchers also found that people with evening chronotypes were found to be more likely to drink alcohol in higher quantities, have a low-quality food diet, get less hours of sleep per night, currently smoke, and have weight, BMI, and physical activity rates in the unhealthy range. 

"If we are able to determine a causal link between chronotype and diabetes or other diseases, physicians could better tailor prevention strategies for their patients," said Kianersi. 

The researchers next plan to investigate genetic determinants of chronotype and its association with cardiovascular disease, in addition to diabetes.