Cigarette smoking, environmental tobacco smoke exposure and insulin sensitivity: the Insulin Resistance Atherosclerosis Study.

PURPOSE: To investigate whether active smoking and/or exposure to environmental tobacco smoke (ETS) is associated with insulin sensitivity.
METHODS: Insulin sensitivity and tobacco use history were measured in 1481 participants in the Insulin Resistance Atherosclerosis Study (IRAS). IRAS is a large mulitcenter epidemiologic study designed to explore the cross-sectional relationships among insulin resistance, cardiovascular disease risk factors and behaviors, and disease in African-American, Hispanic, and non-Hispanic white men and women, aged 40-69 years, selected to represent a broad range of glucose tolerance. Multiple linear regression models and linear contrasts were employed to describe the association between smoking history, as assessed via structured interview, and insulin sensitivity, as assessed by an insulin modified frequently sampled intravenous glucose tolerance test (FSIGT) with minimal model analysis.
RESULTS: Active smoking was not associated with insulin sensitivity. Exposure to ETS was associated with lower insulin sensitivity. Specifically, for all participants combined, levels of SI were lower, indicating reduced insulin sensitivity, for those exposed to ETS when compared to those who were not exposed (p = 0.019). This association persisted for female participants (p = 0.013) and exhibited the same trend for males but failed to achieve statistical significance (p = 0.264).
CONCLUSIONS: Our study did not reveal an association between active smoking and insulin sensitivity, as has been shown previously. The association between ETS exposure and insulin sensitivity is a puzzling finding which deserves further investigation in the longitudinal data from IRAS as well as in other populations.