Smoking Cessation, Weight Change, Type 2 Diabetes, and Mortality

METHODS

In three cohort studies involving men and women in the United States, we identified those who had reported quitting smoking and we prospectively assessed changes in smoking status and body weight. We estimated risks of type 2 diabetes, death from cardiovascular disease, and death from any cause among those who had reported quitting smoking, according to weight changes after smoking cessation.

RESULTS

The risk of type 2 diabetes was higher among recent quitters (2 to 6 years since smoking cessation) than among current smokers (hazard ratio, 1.22; 95% confidence interval [CI], 1.12 to 1.32). The risk peaked 5 to 7 years after quitting and then gradually decreased. The temporary increase in the risk of type 2 diabetes was directly proportional to weight gain, and the risk was not increased among quitters without weight gain (P<0.001 for interaction). In contrast, quitters did not have a temporary increase in mortality, regardless of weight change after quitting. As compared with current smokers, the hazard ratios for death from cardiovascular disease were 0.69 (95% CI, 0.54 to 0.88) among recent quitters without weight gain, 0.47 (95% CI, 0.35 to 0.63) among those with weight gain of 0.1 to 5.0 kg, 0.25 (95% CI, 0.15 to 0.42) among those with weight gain of 5.1 to 10.0 kg, 0.33 (95% CI, 0.18 to 0.60) among those with weight gain of more than 10.0 kg, and 0.50 (95% CI, 0.46 to 0.55) among longer-term quitters (>6 years since smoking cessation). Similar associations were observed for death from any cause.

CONCLUSIONS

Smoking cessation that was accompanied by substantial weight gain was associated with an increased short-term risk of type 2 diabetes but did not mitigate the benefits of quitting smoking on reducing cardiovascular and all-cause mortality. (Funded by the National Institutes of Health.)

Smoking cessation reduces the risk of major chronic diseases and extends life expectancy,1 but considerable weight gain may occur in quitters after cessation.2 Such weight gain is probably due to increased appetite and reduced energy expenditure3 and may discourage quitting attempts and potentially attenuate the health benefits of smoking cessation through increasing the risk of cardiometabolic disease and premature death.4 Despite this concern, evidence regarding the health consequences of weight gain after smoking cessation is equivocal.5-9 The inconsistent findings may be due to the fact that previous observational studies largely relied on the “point prevalence”10 of smoking cessation (i.e., assessment of smoking status at one particular follow-up period only), and possible changes in smoking behavior during follow-up were usually unknown. It has been reported that more than 30% of quitters who were abstinent for 1 year eventually had a relapse within the next decade.11

With longitudinal, repeated assessments of smoking status and body weight in large cohort studies of men and women in the United States, the current investigation aimed to evaluate the risk trajectories of disease and death among those who reported quitting smoking, according to body-weight changes after smoking cessation.

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