Writing in the journal Diabetes Care, the researchers analysed information about 100,000 women taking part in a large-scale national study. Some of the questions they were asked were not just about whether or not they smoked, but how much time they spent around other people's cigarette smoke.
The researchers may not have been surprised to discover the women who smoked more than two packs of cigarettes a day were among those who had the highest risk of developing type 2 diabetes - about 30 out of every 10,000 women every year, according to the statistics, compared to 25 in 10,000 women who didn't smoke.
But the real surprise was that about 39 out of every 10,000 women exposed to second-hand smoke also developed diabetes each year, suggesting passive smoking may be even more risky than smoking in terms of diabetes risk. Ex-smokers also have a higher risk of developing diabetes, the study suggests.
The reason why smoking (passive or otherwise) and type 2 diabetes are linked isn't clear, but some experts suggest it could have something to do with the way smoking causes inflammation. The study, however, doesn't prove that smoking causes diabetes - but there's a good chance there's some type of association between the two.
What would make you quit smoking?