Weight gain after smoking cessation could temporarily increase diabetes risk
medwireNews: Study results published in The New England Journal of Medicine suggest that people who gain weight after stopping smoking may experience a temporary increase in their risk for type 2 diabetes.
However, Qi Sun (Harvard TH Chan School of Public Health, Boston, Massachusetts, USA) and study co-authors emphasize that this short-term increased risk “did not attenuate the benefits of smoking cessation on reducing total and cardiovascular mortality.”
The team analyzed data from three US cohort studies – the Nurses’ Health Study, the Nurses’ Health Study II, and the Health Professionals Follow-up Study – finding that 12,384 individuals developed type 2 diabetes over an average follow-up of 19.6 years.
Overall, people who had quit smoking in the past 2–6 years (recent quitters) had a significant 22% higher risk for type 2 diabetes than current smokers after adjustment for factors including age, sex, race, baseline BMI, and comorbidities. This risk peaked at 5–7 years after smoking cessation, gradually decreasing thereafter, and quitters’ diabetes risk dropped to the same level as that of people who had never smoked after 30 years.
Sun and team explain that the increased diabetes risk occurred “primarily among quitters who gained weight.” Indeed, compared with current smokers, recent quitters who did not gain weight and those who gained 0.1–5.0 kg within the first 6 years of stopping smoking did not experience a significant increase in diabetes risk, while those who gained 5.1–10.0 kg and more than 10.0 kg had a significant 36% and 59% increased risk, respectively.
Despite having an elevated short-term risk for diabetes, people who quit smoking did not experience an increase in cardiovascular or overall mortality risk, regardless of weight change after quitting, say the researchers.
Relative to current smokers, recent quitters without weight gain had a significant 31% reduced risk for death from cardiovascular disease, while recent quitters who gained 0.1–5.0 kg, 5.1–10.0 kg, and more than 10.0 kg had a corresponding 53%, 75%, and 67% reduced risk for cardiovascular death. The team observed similar associations for all-cause mortality.
Overall, these findings provide “reassurance that the benefits of smoking cessation outweigh the risks of obesity-associated diabetes,” says Steven Schroeder (University of California, San Francisco, USA) in an accompanying editorial.
Nonetheless, the study authors believe that “preventing excessive weight gain may maximize the health benefits of smoking cessation through reducing the short-term risk of diabetes and further lowering the long-term risk of death.”
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