Findings demonstrate interactions of smoking and diabetes with each other in relation to elevated risk of cardiovascular disease (CVD) events. Current or former smoking attenuated the beneficial impact of risk factor management on CVD risk among patients with diabetes.

• In this nationwide, population-based, prospective cohort study of 126,181 participants aged 40 years or older who were free from CVD at baseline, the links and interactions of smoking, diabetes, and risk factor management in relation to incident CVD were assessed.

• Relative to never smokers, heavy smokers were found to have a greater risk of CVD events among those with diabetes (multivariable-adjusted hazard ratio [HR], 1.45) vs among those without diabetes (HR, 1.20).

• Compared to participants without diabetes, diabetics who were never smokers and had 5 or more controlled risk factors demonstrated no significantly excess CVD risk (HR, 0.93), but risk factor management-induced cardiovascular benefits were counteracted in diabetics who were current smokers (HR, 1.28) or former smokers (HR, 1.22).