Researchers from Harvard University's School of Public Health, Huazhong University of Science and Technology in China, and National University of Singapore estimated that 11.7 per cent of cases of type 2 diabetes in men and 2.4 per cent in women (about 27.8 million cases in total worldwide) may be attributable to active smoking.
They also found that risk decreases as time elapses after smokers quit.
"Cigarette smoking should be considered as a key modifiable risk factor for diabetes. Public health efforts to reduce smoking will have a substantial impact on the global burden of type 2 diabetes," said co-author Frank Hu, professor at the Harvard T H Chan School of Public Health.
In the study, researchers conducted a meta-analysis of 88 previous studies on the association between smoking and type 2 diabetes risk, looking at health data from nearly 6 million study participants.
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They found that when compared with people who never smoked, current smoking increased the risk of type 2 diabetes by 37 per cent; former smoking by 14 per cent; and passive smoking (breathing in second-hand smoke) by 22 per cent.
Among current smokers, the amount smoked made a difference. The increased risk of developing type 2 diabetes was 21 per cent, 34 per cent, and 57 per cent for light, moderate, and heavy smokers, respectively, compared with those who never smoked.
"Despite the global efforts to combat the tobacco epidemic, cigarette use remains the leading cause of mortality and morbidity worldwide," said first author An Pan, professor at the Huazhong University of Science and Technology.