Weight gain blunts benefits of quitting smoking in type 2 diabetes
medwireNews: Gaining weight after stopping smoking attenuates the cardiovascular disease (CVD) benefits of quitting in people with type 2 diabetes, but does not appear to lessen its positive effect on mortality, shows research.
“These findings are of substantial public health significance, since the fear of weight gain after smoking cessation is the main reason for not attempting to quit smoking or for relapsing after a short attempt for many people,” write Qi Sun (Harvard TH Chan School of Public Health, Boston, Massachusetts, USA) and co-researchers.
As reported in The Lancet Diabetes & Endocrinology, the team analyzed data from people with type 2 diabetes who participated in the Nurses’ Health Study or the Health Professionals Follow-Up Study.
Of the 10,809 people included in the CVD analysis, 2580 had a first event during 153,166 person–years of follow-up. At the time of diagnosis, 24.4% were current smokers; during follow-up, recent quitters (<6 years) had a significant 17% reduced risk for a first CVD event compared with those who continued to smoke after accounting for variables including diabetes duration, prediagnosis BMI, and medication use.
However, this varied by the amount of weight gained. Specifically, people who did not gain any weight after quitting had a 23% reduced CVD risk relative to those who continued smoking, similar to the 28% risk reduction seen in long-term quitters; the risk reduction in never smokers was 41%.
But those who gained up to 5 kg had no reduction in their CVD risk, while those who gained more than 5 kg had a nonsignificant 11% risk reduction. There was a similar pattern for the individual outcomes of coronary heart disease and stroke.
“This finding is in line with accumulating evidence suggesting that excess weight gain could result in alterations in lipids, blood pressure, coagulation, and inflammation, and subsequently endothelial dysfunction and atherosclerosis,” say the researchers.
The 9688 people in the mortality analysis excluded people who had quit smoking less than 6 years previously, which the team explains was to remove the potential for reverse-causation bias “ie, patients with diabetes who died soon after quitting were likely to have a severe disease that resulted in both smoking cessation and weight loss.”
A total of 3827 people died during follow-up, and this risk was a significant 60% less in never smokers than current smokers. The long-term quitters also had a significantly reduced mortality risk, which, notably, was not attenuated if they had gained weight during the first 2–6 years after they quit, with risk reductions of 31%, 43%, and 49% for those who gained 0.0, 0.1–5.0, and more than 5.0 kg, respectively.
“[T]hese data suggest that weight gain did not attenuate the reductions in mortality seen after long-term cessation of smoking, and preventing excessive weight gain might maximise the health benefits of smoking cessation on reducing cardiovascular disease complications among people with type 2 diabetes,” say Sun and team.
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