Smoking and cardiovascular disease in patients with type 2 diabetes: a prospective observational study

BACKGROUND: Cigarette smoking is a major risk factor for cardiovascular disease. In type 2 diabetes mellitus (T2D), medications such as antihypertensives and statins can reduce the increased cardiovascular risk. The aim of this study was to evaluate the impact of cigarette smoking on major adverse cardiovascular event (MACE) and all-cause mortality in patients with T2D in a relatively well treated Swedish cohort. METHODS: Seven hundred and sixty-one patients with T2D aged 55–66 years were followed in the prospective observational CArdiovascular Risk factors in patients with DIabetes – a Prospective study in Primary care (CARDIPP) study. Baseline data included blood samples of markers of dysglycemia and inflammation, blood pressure as well as questionnaire responses regarding cigarette smoking. Participants were followed for incidence of MACE and all-cause mortality. RESULTS: Of the included 663 participants, the mean age was 60.6 (SD 3.1) years and 423 (63.8%) were men. Levels of C-reactive protein and vitamin D, as well as the proportion of participants treated with antihypertensives, acetylic salicylic acid, statins, and diabetes medications, were similar between smokers and nonsmokers. Median follow-up time was 11.9 (Q1–Q3 10.8–12.7) years. Cigarette smoking was associated with all-cause mortality [hazard ratio 2.24 (95% confidence interval, 95% CI 1.40–3.56), P < 0.001], but not MACE [hazard ratio 1.30 (95% CI 0.77–2.18), P = 0.328]. CONCLUSION: In patients with T2D, cigarette smoking was not associated with an increased risk of MACE. This raises the question of whether cardioprotective drugs in individuals with T2D to some degree mitigate the cardiovascular harm of smoking, even though they do not affect other dire consequences of smoking.