Risk of incident type 2 diabetes in male NAFLD and NAFLD-free smokers: a 7-year post-cessation study

We aimed to investigate the post-cessation T2DM risk in male NAFLD and NAFLD-free smokers in a 7-year cohort study.

The study population was male adults who underwent annual health checkups in a 7-year cohort study. Recent quitters were categorized into four groups based on their weight gain during follow-up: < 0 kg, 0–1.9 kg, 2.0–3.9 kg, and ≥ 4.0 kg. Cox proportional hazard models, adjusted for various variables, were used to estimate hazard ratios (HRs) for the association between post-cessation weight gain and incident T2DM in NAFLD and NAFLD-free individuals.

At baseline, we included 1,409 NAFLD and 5150 NAFLD-free individuals. During a total of 39,259 person-years of follow-up, 222 (15.8%) NAFLD patients and 621 (12.1%) NAFLD-free participants quit smoking, with the corresponding means (standard deviations) of post-cessation weight gain being 2.24 (3.26) kg and 1.15 (3.51) kg, respectively. Among NAFLD individuals, compared to current smokers, the fully adjusted HRs (95% CI) for incident T2DM were 0.41 (0.06–3.01), 2.39 (1.21–4.70), 4.48 (2.63–7.63), and 6.42 (3.68–11.23) for quitters with weight gains < 0 kg, 0.0–1.9 kg, 2.0–3.9 kg, and ≥ 4.0 kg, respectively. For NAFLD-free individuals, we only observed a significant association between post-cessation weight gain ≥ 4.0 kg and the risk of incident T2DM (P < 0.001). Further analysis revealed that the impact of post-cessation weight gain on T2DM risk was not affected by alcohol consumption or obesity status at baseline.

Mild post-cessation weight gain significantly increased the risk of T2DM in male NAFLD patients but not in male NAFLD-free individuals. Therefore, it is recommended that individuals with NAFLD manage their weight after quitting smoking.