OBJECTIVE The objective of this study was to evaluate the relationship between childhood and adult secondhand smoke and type 2 diabetes.

RESEARCH DESIGN AND METHODS We conducted a prospective cohort study among 37,343 French women from the E3N-EPIC (Etude Epidémiologique auprès des femmes de la Mutuelle Générale de l’Education Nationale-European Prospective Investigation into Cancer and Nutrition) who never smoked and who were free of type 2 diabetes, cancer, or cardiovascular disease at baseline in 1992. Self-reported childhood secondhand smoke exposure was defined as having at least one parent who smoked. Adult secondhand smoke was defined as the sum of self-reported hours recorded at baseline of exposure to tobacco smoke from a spouse who smoked (or domestic close contact) and from outside the home.

RESULTS Between 1992 and 2007, 795 cases of incident type 2 diabetes were identified and validated through a drug reimbursement dataset and a specific questionnaire. Women with at least one parent who smoked appeared to have an 18% higher rate of type 2 diabetes than women with parents who did not smoke (age-adjusted hazard ratio 1.18 [95% CI 1.02–1.36]). Adult secondhand smoke exposure (no exposure versus ≥4 h/day) was associated with an increased rate of type 2 diabetes (1.36 [1.05–1.77], P = 0.002 for trend) after adjusting for parental history of diabetes, education, body silhouette at age 8, childhood secondhand smoke exposure, physical activity, body mass index, hypertension, hypercholesterolemia, menopausal status and hormone use, alcohol intake, and processed red meat and coffee consumption.

CONCLUSIONS This prospective analysis suggests that secondhand smoke exposure in childhood and adulthood are associated with a higher rate of type 2 diabetes.