Abstract 041: Smoking Cessation and Subsequent Risk of Type 2 Diabetes in Three Large Prospective Cohort Studies of Americans

Background: The inter-relationships between smoking cessation, subsequent weight change, and type 2 diabetes (T2D) risk remain to be characterized. Methods: We prospectively followed 153,123 U.S. men and women from the Health Professionals Follow-up Study (1988-2012), Nurses’ Health Study (NHS, 1984-2012), and NHS II (1991-2013). Participants were followed biennially for smoking status, weight change, and diabetes risk. Self-reported T2D was confirmed using a validated supplementary questionnaire. Results: Compared with current smokers, T2D risk among quitters significantly increased and peaked after 5-7 years of quitting, and gradually decreased along extended durations. With a mean quitting duration of 9.9 years, the multivariate-adjusted hazard ratio (HR; 95% confidence intervals [95% CI]) of T2D was 1.26 (1.14, 1.39) for recent quitters (≤6 consecutive years) and1.04 (0.95, 1.14) for longer-term quitters in three cohorts. The T2D risk approached that of never smokers after 30 years of quitting among older nurses. There was, on average, 5.5 kg weight gain within 6 years of smoking cessation whereas 2.2 kg was gained in the same period among current smokers. The weight change significantly modified the association of smoking cessation with T2D risk ( p for interaction = 0.04): for quitters without weight gain (≤0 kg), 0-5 kg weight gain, and ≥5 kg weight gain within 6 years of smoking cessation, the HRs (95% CIs) of T2D were 0.92(0.73, 1.14), 1.27(1.10, 1.46) and 1.47(1.29, 1.67), respectively, compared with current smokers. We estimated that for quitters who did not gain weight within the first 6 years, their T2D risk approached that of never smokers after 5 years of quitting. Weight change within 6 years of quitting explained 22% (14.8%, 30.1%) of the elevated risk of T2D. Conclusions: Weight gain after quitting smoking may significantly attenuate the benefits of smoking cessation by increasing T2D risk. Our findings underscore the importance of weight control after quitting in maximizing the benefits of smoking cessation.