Taking steps to manage cardiovascular risk can help improve long-term outcomes for type 2 diabetes mellitus, according to two new studies published Aug. 16 in the New England Journal of Medicine.
The first study, which examined weight gain after smoking cessation, found that despite a temporary increase in T2DM risk, post-cessation weight gain did not diminish the long-term benefits of reduced cardiovascular and all-cause mortality.
The analysis included three cohort studies: the Nurses’ Health Study (NHS), Nurses’ Health Study II (NHS II), and the Health Professionals Follow-Up Study (HPFS), with follow-up questionnaires every 2 years. After exclusions, a total of 162,807 patients were included in the diabetes analysis and 170,723 in the mortality analysis, reported Yang Hu of the department of nutrition at Harvard T.H. Chan School of Public Health, Boston, and his coauthors (N Engl J Med. 2018 Aug 16. doi: 10.1056/NEJMoa1803626).
In each follow-up cycle, participants who reported being smokers in the previous cycle but “past” smokers in the current cycle were identified. Quitters were defined as either transient quitters (past smokers in the current cycle but current smokers in previous and next cycles), recent quitters (2-6 consecutive years since smoking cessation), and long-term quitters (6 or more consecutive years since cessation). Weight change was observed for the first 6 years after quitting.
Overall, 12,384 cases of T2DM were confirmed. Diabetes risk was higher for recent quitters than for current smokers (hazard ratio, 1.22; 95% confidence interval, 1.12-1.32); this risk peaked 5-7 years after quitting and then gradually decreased. In analysis of patients with the longest follow-up time, diabetes risk dropped after 30 years of cessation to that of participants who had never smoked, the authors reported.
Compared with current smokers, hazard ratios for T2DM in recent quitters were 1.08 (95% CI, 0.93-1.26) for those without weight gain, 1.15 (95% CI, 0.99-1.33) for those with weight gain of 0.1-5.0 kg, 1.36 (95% CI, 1.16-1.58) for those with weight gain of 5.1-10 kg, and 1.59 (95% CI, 1.36-1.85) in those with weight gain of more than 10 kg.
In the mortality analysis, 23,867 deaths occurred, of which 5,492 were due to cardiovascular disease. Compared with current smokers, hazard ratios for death from cardiovascular disease in recent quitters were 0.69 (95% CI, 0.54-0.88) in those without weight gain; 0.47 (95% CI, 0.35-0.63) in those with weight gain of 0.1-5 kg; 0.25 (95% CI, 0.15-0.42) in those with weight gain of 5.1-10 kg; 0.33 (95% CI, 0.18-0.60) in those with weight gain of more than 10 kg; and 0.50 (95% CI, 0.46-0.55) for longer term quitters. The corresponding hazard ratios for all-cause deaths in the same weight gain groups were 0.81 (95% CI, 0.73-0.90); 0.52 (95% CI, 0.46-0.59); 0.46 (95% CI, 0.38-0.55); 0.50 (95% CI, 0.40-0.63); and 0.57 (95% CI, 0.54-0.59).
The findings suggest that weight gain after quitting smoking “did not attenuate the apparent benefits of smoking cessation on reducing cardiovascular mortality or extending longevity,” the authors said. “However, 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.”