Could Smoking Increase the Risk of Type 2 Diabetes?

Individuals who smoke—whether they are current smokers, former, or passive—have an increased risk for type 2 diabetes than those who have never smoked, according to a new meta-analysis.

While previous research has linked cigarette smoking to cancer, respiratory disease, and cardiovascular disease, little data has been able to connect the practice with the risk of type 2 diabetes.
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In order to further evaluate this relationship, researchers conducted a meta-analysis of 88 studies, including data from 5,898,795 individuals and 295,446 cases of type 2 diabetes.

Overall, they found that current smokers had an average of 37% greater risk of developing type 2 diabetes than nonsmokers. Former smokers and those exposed to secondhand smoke, and those who quit smoking had increased risks of 14%, 22%, and 54%, respectively. Researchers noted that in former smokers, risk declined to 11% 10 years after quitting. 

Risk varied among current smokers based on frequency: 21%, 34%, and 57% among light, moderate, and heavy smokers, respectively.

Based on this data and the assumption that the relationship between smoking and diabetes risk is causal, the researchers estimated that 11.7% of cases of type 2 diabetes in men and 2.4% of cases in women were attributable to active smoking.

“If the association between smoking and risk of type 2 diabetes is causal, public health efforts to reduce smoking could have a substantial effect on the worldwide burden of type 2 diabetes,” they concluded.

—Michael Potts

Pan A, Wang Y, Talaei M, et al. Relation of active, passive, and quitting smoking with incident type 2 diabetes: a systematic review and meta-analysis. Lancet Diabetes and Endocrinology. September 17, 2015 [epub ahead of print]. DOI: http://dx.doi.org/10.1016/S2213-8587(15)00316-2.