Factors associated with continued smoking after the diagnosis of type 2 diabetes: a retrospective study in the Korean cohort

Objective To investigate the factors associated with continued smoking in patients newly diagnosed with type 2 diabetes. Design Retrospective study using the Korean National Health Insurance Service-National Health Screening Cohort (2002-2013) database. Participants Male patients newly diagnosed with type 2 diabetes between 1 January 2004 and 31 December 2011. Measurement Change in smoking behaviour after the diabetes diagnosis was assessed using a self-reported questionnaire, which was administered before and after the diagnosis. To identify the factors associated with continued smoking after diabetes diagnosis, a multivariate-adjusted logistic regression was conducted using only the variables with statistical significance from the univariate analyses. Results Younger age, lower economic status, heavier smoking habit, lower Charlson Comorbidity Index and comorbid hypertension were identified as factors associated with continued smoking after the diagnosis of type 2 diabetes. Older patients (adjusted OR (a0R) 0.71, 95% CI 0.63 to 0.79) and patients with longer diabetic duration (1-2 years OR 0.88, 95% CI 0.80 to 0.98, >= 3 years OR 0.63, 95% CI 0.55 to 0.73) were more likely to quit smoking. Contrastingly, smokers in the lower economic status (aOR 1.29, 95% CI 1.18 to 1.42) and heavier smoking habit (moderate: aOR 1.53, 950/0 CI 1.35 to 1.72; heavy: aOR 1.90, 95% CI 1.67 to 2.17) categories were more likely to continue smoking after the diagnosis. Conclusions It is important to identify the factors associated with smoking behaviour in patients with type 2 diabetes. Recognising the factors that contribute to the vulnerability of patients to continued smoking will be helpful in developing policies and intervention strategies in future. Vulnerable patients may require intensive education and encouragement to quit smoking. We recommend physicians to take a more proactive approach, such as encouraging frequent clinical sessions for behavioural counselling and even early pharmacological interventions, when they encounter patients with the factors outlined in this study.