US researchers have reported some of the strongest evidence yet on the link between smoking and type 2 diabetes. Their meta-analysis shows that heavy smokers are 61% more likely to develop the disease.

Dr Carole Willi and colleagues gathered data from 25 prospect cohort studies including 1.2 million participants. Overall, they found that current smokers were 44% more likely than non-smokers to develop type 2 diabetes.

Those who smoked under 20 cigarettes a day were at 29% higher risk while former smokers were still at an increased risk—23% higher than non-smokers, according to the report in JAMA.

Other studies have made the correlation between smoking and diabetes, but the link has not been given adequate prominence, editorialists argue in the journal. “The adverse effect of smoking on type 2 diabetes has been generally under recognized,” they say.

The study is likely to underestimate of the true association between smoking and type 2 diabetes, say Drs Eric Ding and Frank Hu.  They calculate that about 12% of all type 2 diabetes in the US may be attributable to smoking.

Given this, Drs Ding and Hu suggest GPs should incorporate smoking cessation messages into their recommendations for type 2 diabetes prevention. “An estimated 91% of all type 2 diabetes is preventable by smoking prevention and lifestyle modification,” they say.