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

Abstract

Background: Whether weight gain after smoking cessation attenuates the health benefits of quitting is unclear.

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.).

Figure 1.. Association between Duration of Smoking Cessation and Risk of Type 2 Diabetes.

Panel A shows the risk of type 2 diabetes according to years since smoking cessation, as compared with the risk among current smokers. P<0.001 for nonlinearity. “All quitters” indicates all persons who had reported quitting smoking. Panel B shows the risk of type 2 diabetes according to years since smoking cessation and weight change within 6 years after quitting, as compared with the risk among current smokers. P values for nonlinearity were 0.33 for no weight gain, 0.59 for weight gain of 0.1 to 5.0 kg, 0.01 for weight gain of 5.1 to 10.0 kg, and less than 0.001 for weight gain of more than 10.0 kg. Multivariate analyses were adjusted for age (in months, continuous), cohort (Nurses’ Health Study [NHS], Nurses’ Health Study II [NHS II], or Health Professionals Follow-up Study [HPFS]), sex (male or female), race (white, black, Asian, or other), physical activity (in quintiles), baseline body-mass index (BMI, in continuous and quadratic terms), alcohol intake (0, <5.0, 5.0 to 9.9, 10.0 to 14.9, 15.0 to 29.9, or >30.0 g per day), history of hypertension (yes or no), history of hypercholesterolemia (yes or no), family history of diabetes (yes or no), multivitamin use (yes or no), Alternative Healthy Eating Index score (in quintiles), and total energy intake (in quintiles). Dotted lines represent 95% confidence intervals.

Figure 2.. Association between Duration of Smoking Cessation and Risk of Death from Cardiovascular Disease (CVD) and Death from Any Cause.

Panel A shows the risk of death from CVD according to years since smoking cessation, as compared with the risk among current smokers. P<0.001 for nonlinearity. Panel B shows the risk of death from CVD according to years since smoking cessation and weight change within 6 years after quitting, as compared with the risk among current smokers. P values for nonlinearity were 0.01 for no weight gain and less than 0.001 for weight gain of 0.1 to 5.0 kg, 5.1 to 10.0 kg, and more than 10.0 kg. Panel C shows the risk of death from any cause according to years since smoking cessation, as compared with the risk among current smokers. P<0.001 for nonlinearity. Panel D shows the risk of death from any cause according to years since smoking cessation and weight change within 6 years after quitting, as compared with the risk among current smokers. P values for nonlinearity were 0.95 for no weight gain and less than 0.001 for weight gain of 0.1 to 5.0 kg, 5.1 to 10.0 kg, and more than 10.0 kg. Multivariate analyses were adjusted for age (in months, continuous), cohort (NHS, NHS II, or HPFS), sex (male or female), race (white, black, Asian, or other), physical activity (in quintiles), baseline BMI (in continuous and quadratic terms), alcohol intake (0, <5.0, 5.0 to 9.9, 10.0 to 14.9, 15.0 to 29.9, or >30.0 g per day), history of hypertension (yes or no), history of hypercholesterolemia (yes or no), family history of diabetes (yes or no), family history of myocardial infarction (yes or no), multivitamin use (yes or no), Alternative Healthy Eating Index score (in quintiles), and total energy intake (in quintiles). Dotted lines represent 95% confidence intervals.