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Research Paper
The impact of smoking on diabetic complications: data from the National Health Insurance Service-National Health Screening Cohort (2002–2019)
Seonmi Yeom1orcid, Youngran Yang1,2orcid

DOI: https://doi.org/10.4040/jkan.24109
Published online: April 21, 2025

1Research Institute of Nursing Science, College of Nursing, Jeonbuk National University, Jeonju, Korea

2Biomedical Research Institute, Jeonbuk National University Hospital, Jeonju, Korea

Corresponding author: Youngran Yang Research Institute of Nursing Science, College of Nursing, Jeonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju 54896, Korea E-mail: youngran13@jbnu.ac.kr
†This work was presented at 2024 CUK-AAPINA Conference, May, 2024, Seoul, South Korea.
• Received: September 9, 2024   • Revised: December 16, 2024   • Accepted: February 12, 2025

© 2025 Korean Society of Nursing Science

This is an Open Access article distributed under the terms of the Creative Commons Attribution NoDerivs License (http://creativecommons.org/licenses/by-nd/4.0) If the original work is properly cited and retained without any modification or reproduction, it can be used and re-distributed in any format and medium.

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  • Purpose
    This study aimed to examine the effects of smoking on the incidence of macrovascular and microvascular complications in patients with type 2 diabetes.
  • Methods
    We analyzed 35,804 patients diagnosed with type 2 diabetes between 2004 and 2017 using the Korean National Health Insurance Service–National Health Screening Cohort (2002–2019). Smoking status was categorized into never, former, and current smokers, with further classification based on duration of smoking and daily smoking amount. We conducted survival analysis using a Cox proportional hazards model.
  • Results
    Both former and current smokers had significantly elevated risks of macrovascular complications compared to non-smokers, with hazard ratios (HRs) of 1.60 (95% confidence interval [CI], 1.49–1.66) and 1.10 (95% CI, 1.08–1.17), respectively. Long-term smokers (over 30 years) had significantly higher risks of both macrovascular (HR, 1.35; 95% CI, 1.29–1.42) and microvascular complications (HR, 1.36; 95% CI, 1.30–1.42). Heavy smokers (over 2 packs/day) had a higher risk of developing macrovascular (HR, 1.46; 95% CI, 1.30–1.64) and microvascular (HR, 1.78; 95% CI, 1.60–1.98) complications than never smokers. Notably, former smokers had increased risks of developing neuropathy (HR, 1.40; 95% CI, 1.31–1.49), nephropathy (HR, 1.27; 95% CI, 1.16–1.39), and retinopathy (HR, 1.49; 95% CI, 1.39–1.60).
  • Conclusion
    Patients with type 2 diabetes and a history of smoking are at higher risk of developing macrovascular and microvascular complications. Smoking cessation, along with reducing smoking duration and amount, is crucial for lowering these risks.
  • Key words: Diabetes complications; Diabetes mellitus; Smoking
In 2021, diabetes affected approximately 537 million adults worldwide, contributing to 12.2% of global adult deaths and positioning it among the top 10 causes of mortality, with cases expected to increase by 46% by 2045 [1]. In Korea, the prevalence of diabetes reached 16.7% in 2020, with diabetes-related deaths increasing by 61% over the previous decade [2]. Chronic diabetic complications stem from prolonged high blood glucose, leading to cellular damage and vascular issues categorized as macrovascular (cardiovascular, cerebrovascular, and peripheral diseases) and microvascular (retina, kidney, and nerve damage) complications [3,4]. Patients with one complication often develop additional issues, such as lower-extremity ulcers and amputations, significantly reducing their quality of life [5,6].
Smoking adversely impacts pancreatic β-cell function, altering insulin secretion and mediating insulin resistance, which can lead to impaired glycemic control [7]. Additionally, it contributes to endothelial dysfunction, playing a critical role in the development of both macrovascular and microvascular complications [7]. Research on the link between smoking and cardiovascular disease in diabetes has shown significant differences in glycated hemoglobin and lipid levels between smokers and nonsmokers. These findings suggest that smoking cessation can reduce vascular complications, including cardiovascular disease [8]. A meta-analysis of prospective cohort studies found that smoking increased macrovascular complications and mortality in patients with diabetes, while smoking cessation mitigated this risk [9]. Additionally, a cohort study highlighted the role of smoking in worsening diabetic nephropathy in patients with type 1 and type 2 diabetes [10].
Smoking, a key lifestyle factor, is a modifiable risk factor for numerous chronic diseases. Its cessation is crucial for diabetes management and prevention of complications [7,11]. Despite strong recommendations for smoking cessation in diabetes management, 22.3% of individuals aged over 30 with diabetes continue to smoke post-diagnosis; this trend is more pronounced in men, with 40% persisting in smoking [2]. This underscores the critical issue of smoking in patients with diabetes. However, its impact on microvascular complications remains unclear because most studies have focused on macrovascular outcomes, with limited and inconsistent findings for microvascular effects [7,12].
This study’s primary objective was to examine variations in the incidence of diabetic complications relative to smoking status, duration of smoking, and daily smoking amount at the time of diagnosis among individuals with diabetes. Factors influencing the development of diabetic complications extend beyond smoking and include sociodemographic and disease-related variables. Therefore, controlling for these confounding variables is essential to accurately understand the sole effect of smoking on diabetic complications. Through this analysis, we aimed to provide substantial foundational data to confirm the need for smoking cessation in patients with diabetes. Furthermore, we emphasize the necessity of smoking cessation in the early stages of diabetes management and aim to establish a theoretical basis for nursing interventions that promote smoking cessation. This study aspires to aid in preventing diabetic complications, thereby prolonging healthy life expectancy, curtailing medical expenses, and improving patients’ quality of life.
1. Data and sample
This study used data from the National Health Insurance Service (NHIS) of Korea, which encompasses extensive health information across the population, including socioeconomic status and medical service utilization. Data were obtained through the National Health Insurance Sharing Service platform by submitting application documents, which included the research proposal and the Institutional Review Board approval notification. After review by the Data Provision Review Committee, data were provided through a remote research analysis system. This dataset includes approximately 1 million individuals, representing approximately 2.1% of the Korean population. Using the entire population as the sampling frame, stratified sampling was performed based on 2,142 strata defined by gender, age, household income, and region. It contains prospective data spanning 18 years, from 2002 to 2019. In this study, 108,694 individuals diagnosed with type 2 diabetes (based on the Korean Standard Classification of Disease [KCD], KCD-4–KCD-7 codes E11–E14) or those prescribed diabetes medications were identified. This study primarily focused on smoking behavior, excluding type 1 diabetes, which is typically more prevalent in younger individuals. In the initial group, 7,220 who had previously been diagnosed with diabetic complications were excluded to concentrate on those without complications at diabetes diagnosis. To secure a minimum 2-year observation period from diagnosis to complication onset [13-15], 36,786 individuals diagnosed with diabetes between 2002 and 2003, those diagnosed between 2018 and 2019, and those who died within 2 years post-diagnosis were also excluded. Furthermore, 28,884 individuals were excluded: 15,306 whose biennial health examination dates fell outside the 2-year window around their diabetes diagnosis, since this period is critical for assessing health status at the time of diagnosis, and 13,578 with missing smoking-related information in their records. Consequently, 35,804 individuals were included in this study (Figure 1, Appendix 1).
2. Variables
In this study, diabetic complications were defined as macrovascular (cerebrovascular disease, cardiovascular disease, and peripheral vascular disease) and microvascular complications (nephropathy, neuropathy, retinopathy) [16]. Specifically, these include diseases listed in the Diabetes Complications Severity Index [15,16], and all relevant disease codes from the 4th to 7th revisions of the KCD. A complication was defined as diabetic if there was a claim record with a relevant disease code 2 years after being diagnosed with diabetes.
Smoking variables included smoking status, duration of smoking, and daily smoking amount. Smoking status was categorized into never smoked, former smoker (previously smoked but currently not smoking), and current smoker. Duration of smoking was classified as never smoked, less than 10 years, more than 10 to less than 20 years, more than 20 to less than 30 years, and more than 30 years. Daily smoking amount was divided into does not smoke, less than one pack, more than one pack to less than two packs, and more than two packs. These variables were measured close to the time of diabetes diagnosis and categorized to account for changes in health examination items over time. The use of smoking history at the time of diabetes diagnosis in this study reflected the study’s objectives and was based on previous research findings indicating that smoking habits among patients with diabetes did not change significantly after the time of diabetes diagnosis [17].
Sociodemographic characteristics included gender, age, and household income level, which were based on the time of diabetes diagnosis. Income levels were categorized into low-, middle-, and high-income groups based on health insurance premium brackets. Disease-related characteristics included diabetes medication use, duration of diabetes, and comorbidities. The variable for diabetes medication use was based on the observation period of the study, using the modified medication possession ratio (MPRm) [18], and was categorized into poor and good adherence groups based on an 80% threshold [19]. Comorbidities were included for the period from 1 year prior to diabetes diagnosis up to the diagnosis date and measured using the Charlson comorbidity index (CCI) [20]. Lifestyle-related variables, besides smoking, included heavy drinking, binge drinking, and exercise. Heavy drinking was defined based on the average weekly alcohol consumption (19% soju 94 mL, men >2 bottles, men aged ≥65 years & women >1 bottle, women aged ≥65 years >1/2 bottle), while binge drinking was defined by the amount consumed per occasion (men >3/4 bottle, men aged ≥65 years & women >1/2 bottle, women aged ≥65 years >1/4 bottle), both adjusted for gender and age [21]. Exercise was categorized based on the frequency of weekly physical activity.
3. Statistical analysis
The chi-square tests were employed using SAS software ver. 9.4 (SAS Institute Inc.) to examine differences in the incidence of diabetic complications associated with sociodemographic factors, disease-related factors, and lifestyle-related factors at diabetes diagnosis. Furthermore, we conducted survival analysis using the Cox proportional hazard model with R statistical software ver. 3.3.3 (The R Foundation for Statistical Computing) to evaluate the incidence rates of diabetic complications in relation to smoking status, duration of smoking, and daily smoking amount. Each individual complication was calculated independently, with patients having multiple complications counted more than once. In contrast, the total count of all complications was calculated by excluding overlapping cases.
To ensure validity of the Cox proportional hazards model, we assessed the proportional hazards assumption using log-minus-log survival plots. Graphical inspection revealed no evidence of a violation of the proportional hazards assumption. To control for potential confounding effects, gender, age, household income, comorbidity index (CCI) score, medication possession ratio, alcohol consumption, and physical activity were included as covariates in the Cox proportional hazards model. These variables were chosen based on their potential influence on the incidence of diabetic complications, ensuring that the analysis accurately reflected the relationship between smoking and diabetic complications while minimizing biases introduced by other confounding factors. This study includes only baseline covariates, excluding time-dependent covariates.
4. Ethical considerations
This study was approved by the Institutional Review Board of Jeonbuk National University (JBNU 2021-10-006) and was conducted after receiving approval from the NHIS (NHIS-2022-2-113). The data provided were a subset of records accumulated during the course of the NHIS’s operations. Personal identifiers and sensitive information were anonymized before being made available to the researchers who conducted the study remotely in a restricted virtual research environment.
1. Differences in the incidence of complications based on sociodemographic characteristics, disease-related characteristics, and lifestyle-related factors
The final number of participants included in the analysis was 35,804, comprising 56.2% men and 43.8% women. Those in their 50s and 60s comprised 58.4% of the participants. Regarding the duration of diabetes, 40.9% had been diagnosed for more than 5 years but less than 10 years, whereas 26.5% had been diagnosed for over 10 years. During the observation period, the incidence of at least one type of diabetic complication was 81.6%, showing statistically significant differences based on gender, age, CCI, duration of diabetes, smoking status, duration of smoking, daily smoking amount, and physical activity. The groups with the highest complication rates were women (85.8%), those aged over 70 years (88.3%), individuals with a diabetes duration of over 10 years (92.8%), those who had smoked for over 30 years (80.0%), and those who smoked more than two packs a day (78.0%).
There were significant differences in the incidence rate of all macrovascular complications based on gender (women), age (70s and older), duration of diabetes (over 10 years), smoking status (never smoked), duration of smoking (over 30 years), daily smoking amount, and physical activity (none). Among these, cerebrovascular and cardiovascular diseases also showed significant differences based on household income level and CCI. Similarly, microvascular complications showed significant differences in incidence rates based on gender (women), age (60s), CCI, duration of diabetes (over 10 years), smoking status (never smoked), duration of smoking (over 30 years), daily smoking amount, and physical activity (none). Among the microvascular complications, nephropathy and neuropathy showed significant differences in incidence rates based on the CCI, whereas only retinopathy showed a significant difference based on medication adherence (Table 1).
This study investigated overall trends in the incidence of diabetic complications according to sociodemographic factors, disease-related factors, and lifestyle-related factors at the time of diabetes diagnosis. However, this was not the primary objective of this study. Therefore, the role of these non-smoking-related factors in the incidence of diabetic complications requires further analysis.
2. Differences in the incidence of diabetic complications by smoking status, duration of smoking, and daily smoking amount
As shown in Table 2, hazard ratios were adjusted for factors such as gender, age, household income, CCI score, MPRm, heavy drinking, and physical activity. The risk of any type of diabetic complication was significantly influenced by smoking status, duration of smoking, and daily smoking amount. Former and current smokers had higher risks compared to those who never smoked, with former smokers showing 2.09 times the risk (95% confidence interval [CI], 1.99–2.19) and current smokers 1.21 times the risk (95% CI, 1.17–1.25). The longer the duration of smoking, especially for those who smoked for more than 30 years, the higher the risk, with 1.40 times the risk (95% CI, 1.38–1.49). Furthermore, a higher daily smoking amount also led to an increased risk, particularly for those smoking more than two packs a day, with 1.90 times the risk (95% CI, 1.72–2.08).
An increased risk of developing overall macrovascular complications was observed among former and current smokers compared to those who never smoked, with hazard ratios of 1.60 (95% CI, 1.49–1.66) and 1.10 (95% CI, 1.08–1.17), respectively. Specifically, the risk of developing cardiovascular diseases was higher, at 1.39 times (95% CI, 1.30–1.49) for former smokers and 1.11 times (95% CI, 1.06–1.16) for current smokers. In the case of peripheral vascular disease, only the former smokers had an increased risk of 1.10 times (95% CI, 1.03–1.19) compared to non-smokers. Individuals with a smoking history of over 30 years showed a significantly higher risk of macrovascular complications compared to non-smokers: cerebrovascular disease risk increased by 1.36 times (95% CI, 1.26–1.48), cardiovascular disease by 1.34 times (95% CI, 1.27–1.42), and peripheral vascular disease by 1.15 times (95% CI, 1.08–1.22). Additionally, those who smoked for 20–29 years also showed a heightened risk of cardiovascular disease, 1.16 times higher (95% CI, 1.09–1.24) than non-smokers. The risk of macrovascular complications increases with daily amount of smoking. Those smoking more than two packs a day had a 1.46 times higher risk (95% CI, 1.30–1.64) for macrovascular complications, 1.78 times (95% CI, 1.30–1.98) for cerebrovascular disease, and 1.33 times (95% CI, 1.15–1.53) for cardiovascular disease compared to non-smokers. Peripheral vascular disease risk increased significantly, by 1.08 times (95% CI, 1.02–1.14), in those smoking between one and less than two packs a day.
Smoking also influenced microvascular complications in diabetic patients, increasing the overall risk to 1.81 times (95% CI, 1.72–1.91) in former smokers and 1.16 times (95% CI, 1.11–1.20) in current smokers. The risk for neuropathy was higher, at 1.40 times (95% CI, 1.31–1.49) and 1.10 times (95% CI, 1.08–1.18), respectively. Nephropathy and retinopathy risks were particularly higher in former smokers, with increases of 1.27 times (95% CI, 1.16–1.39) and 1.49 times (95% CI, 1.39–1.6), respectively, compared to non-smokers. Individuals with a smoking history of over 30 years exhibited an increased risk of all types of microvascular complications, ranging from 1.18 to 1.36 times higher. Higher daily smoking amounts further correlated with increased risks of nephropathy, neuropathy, and retinopathy, particularly in individuals smoking more than two packs per day, where the risk rose to 1.78 times (95% CI, 1.60–1.98) for overall microvascular complications.
One of the primary objectives of diabetes management is to prevent complications associated with this condition. The American Diabetes Association (ADA), in its “Standards of Medical Care in Diabetes,” warns that diabetic patients who smoke may face more challenges in controlling their blood sugar levels compared to non-smokers, leading to an increased risk of diabetic complications and potentially early death [11]. The prevalence of smoking among individuals with type 2 diabetes in South Korea remains notably high, at approximately 43.1%, significantly above the global average of 20.8%, as calculated from data across 33 countries, 74 studies, and 3.2 million participants [22].
This study analyzed data from the NHIS of South Korea. This study focused on patients with type 2 diabetes diagnosed between 2004 and 2017 to understand the impact of smoking status, duration of smoking, and daily smoking amount at the time of diagnosis on diabetic complications. The findings showed an increased risk of complications in both former and current smokers compared with non-smokers. This is consistent with previous findings [7,9,12,23,24]. However, unlike prior research suggesting higher risks in current smokers [9,23], this study found that former smokers had a greater risk across all complication types. Considering the dose-dependent effects of smoking reported in prior studies [23,25-27], smoking status must be interpreted in conjunction with duration of smoking and daily smoking amount to provide a more comprehensive understanding. However, in this study, smoking status only reflected smoking exposure at the time of diabetes diagnosis, while quantitative aspects were not considered. According to previous research, smoking habits did not significantly change immediately after a diagnosis of diabetes [17]. This suggests that modifying smoking habits is a challenging task. Based on prior studies, it can be inferred that the former smoker group in this study may have included a substantial number of patients who had quit smoking at the time of diagnosis but had engaged in long-term smoking prior to quitting, possibly due to difficulties in altering their habits [17,23,25-27]. These individuals may have already experienced significant smoking exposure as a result of prolonged smoking durations and increased smoking amounts. The findings of this study may reflect the tendency of patients with diabetes in Korea to face challenges in changing their smoking behaviors. To validate this finding and address the study’s limitation in establishing causal relationships, further studies are required to analyze the differences in the incidence of diabetic complications based on smoking duration and amount among current and former smokers. These studies should consider that survey questions related to smoking habits vary depending on the year of examination, which may limit the analyses to data collected at specific time points.
Regardless of complication type, patients with diabetes and a history of smoking, particularly those with longer smoking durations or higher daily smoking amounts, face an increased risk of developing complications. In complications other than peripheral vascular disease, the greatest risk was observed in patients with the longest smoking history and the highest daily smoking amount. This suggests a potential association, indicating that beyond the presence or absence of smoking, the duration and amount of smoking may play a more significant role in influencing the risk of developing diabetic complications. However, the observational nature of this study precludes establishing a definitive dose-response relationship. These findings underscore the importance of early intervention to reduce long-term and heavy smoking in patients with type 2, to mitigate the risk of complications.
In terms of smoking duration, when it was 20 years or more, and in terms of daily smoking amount, even if it was less than one pack, the risk of developing macrovascular complications was significantly higher in patients with diabetes and a smoking history than in non-smokers. This suggests that long-term smokers with type 2 diabetes may have a relatively higher risk of developing macrovascular complications, and this observed association seems to be stronger with increased daily smoking. Tang et al. [28] reported that patients with type 2 diabetes who smoked one pack a day for over 20 years had a significantly increased risk of cardiovascular diseases compared to non-smokers. Although the present study found no significant differences in cerebrovascular disease risk by overall smoking status, patients with a smoking history of less than 20 years showed a surprisingly lower risk than non-smokers. However, in those with a smoking history of over 30 years, the risk increased significantly and escalated further with higher daily smoking amounts. According to prior research, in patients with type 2 diabetes, factors such as hemoglobin A1c levels, hypertension, and hyperlipidemia may play a more substantial role in the risk of developing cerebrovascular disease compared to smoking, unless the duration of smoking exceeds 30 years or the daily smoking amount is high [29]. This interpretation, while informative, is based on existing literature and was not directly tested in this study, requiring cautious consideration. Furthermore, the finding that patients with a smoking history of less than 20 years had a significantly lower risk of cerebrovascular disease compared to non-smokers may be partially explained by the possibility that some of these patients smoked less during their smoking period or had already quit, thereby potentially adopting healthier lifestyles that might have mitigated the effects of smoking. However, further research is needed to confirm these interpretations. Additionally, among patients with type 2 diabetes and a history of smoking (39.4% of the total), the proportion of those with a smoking history of less than 20 years was relatively low (<10 years: 8.2%; 10 to ≤20 years: 23.4%). Moreover, the number of cerebrovascular disease cases within these groups was also small (<10 years: 9.4%; 10 to ≤20 years: 8.6%), which may have reduced the statistical power and potentially led to an underestimation of the true difference [30]. In this study, patients who smoked more than one pack a day but did not exceed two packs, and those who smoked for over 30 years, showed a significantly higher risk of peripheral vascular disease. This suggests that smoking may be associated with structural abnormalities in the peripheral vasculature and reduced circulation, which could potentially contribute to peripheral vascular diseases such as foot ulcers. Smoking intensity, including duration and amount, appears to have a significant impact [31].
In cases of microvascular complications, even short smoking durations and less than one pack a day were associated with a significantly increased risk compared to non-smokers. This finding suggests that even minimal exposure to smoking may be associated with an increased risk of early microvascular complications in patients with type 2 diabetes. Specifically, the analysis indicated that those who smoked for more than a year or more than one pack a day appeared to have a higher likelihood of retinopathy compared to non-smokers. Contrasting findings were reported by Cai et al. [32], where smoking decreased the risk of retinopathy in patients with type 2 diabetes, while Park et al. [33] indicated that increased smoking duration or amount did not significantly increase the risk of retinopathy. Cai et al. [32] defined smoking status ambiguously and Park et al. [33] included patients with both type 1 and type 2 diabetes. These differences, indicating a distinction from the present study, likely contributed to the differing outcomes for retinopathy. Additionally, Park et al. [33] applied a narrower range of retinopathy definitions than those used in this study, which may explain the differing results. Consequently, further research is necessary to clarify the relationship between smoking and the risk of developing retinopathy. For nephropathy and neuropathy, similar to macrovascular complications, the risk of occurrence increased with smoking duration of over 20 years or with higher daily smoking amounts. The finding that the risk of developing overall microvascular complications significantly increased even with a smoking duration of just over 1 year may reflect the influence of retinopathy; however, this should be interpreted cautiously, given the potential limitations of the study.
This study demonstrated that smoking habits at the time of diabetes diagnosis significantly affected the risk of both macrovascular and microvascular complications in patients with type 2 diabetes. Longer smoking duration and greater daily smoking amount appear to be associated with an increased risk of early complications following diabetes diagnosis. Hence, smoking cessation from an early stage of diabetes management is vital to prevent complications and maintain quality of life [34]. Regarding smoking duration, the risk of diabetic complications generally increased with long-term smoking of 20 years or more, except for retinopathy. However, daily smoking amounts of less than one pack were still significantly associated with an increased risk of complications. Thus, for patients who find immediate smoking cessation challenging, gradually reducing smoking is crucial.
To support patients with diabetes in smoking cessation and managing related complications, nurses can play a pivotal role in the early stages of diabetes diagnosis through patient education and tailored interventions. Nurses can provide targeted smoking cessation counseling, particularly to patients with a long smoking history or high daily smoking intake. Incorporating educational sessions into routine diabetes care, following an assessment of each patient’s smoking behavior, can enhance awareness of the risks associated with prolonged and heavy smoking [35,36]. In personalized intervention plans, motivational interviewing can be employed to strengthen the patients’ commitment to quitting [35]. Additionally, nurses can collaborate with multidisciplinary teams to offer resources such as nicotine replacement therapies and behavioral support programs, which have proven to be effective in facilitating smoking cessation [36].
This study has certain limitations, primarily due to the reliance on self-reported smoking data from health checkup questionnaires, which may not accurately reflect actual behavior due to participants’ reliance on memory. Additionally, health checkup data may omit patients with type 2 diabetes who do not attend health checkups, potentially leading to undercoverage. Therefore, recall bias and undercoverage should be considered when interpreting the results. Furthermore, this study reflected smoking habits at the time of diabetes diagnosis, making it difficult to determine the differences in the incidence of complications based on changes in smoking habits up to the time of complication development. Therefore, additional research is required to continuously track changes in smoking habits from the time of diabetes diagnosis to the onset of complications. However, the data utilized in this study may be limited to health insurance workplace subscribers or individuals who regularly undergo health checkups and actively practice healthy behaviors, leading to potential selection bias. Additionally, individuals with missing smoking-related variables were excluded during the participant selection process. This exclusion may have introduced missing data not at random bias, potentially leading to biased results. Although methods such as multiple imputation or sensitivity analysis could address this issue, they were not implemented in the present study. These factors should be considered when interpreting the results.
In conclusion, this study demonstrates a significant health concern, as it links smoking to increased macrovascular and microvascular complication risks in South Korean patients with type 2 diabetes. This study underscores the importance of smoking cessation and exposure reduction for managing these health risks. The findings highlight the cumulative impact of smoking on diabetic complications, suggesting a pressing need for nursing interventions focused on long-term smoking behavior, including duration and cessation. This insight is crucial for formulating effective nursing interventions to mitigate the burden of diabetes-related complications and for establishing a theoretical basis for such interventions it.

Conflicts of Interest

No potential conflict of interest relevant to this article was reported.

Acknowledgements

None.

Funding

This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (2021R1A2C2092656).

Data Sharing Statement

Please contact the corresponding author for data availability.

Author Contributions

Conceptualization or/and Methodology: SY, YY. Data curation or/and Analysis: SY, YY. Funding acquisition: YY. Investigation: SY, YY. Project administration or/and Supervision: YY. Resources or/and Software: SY, YY. Validation: SY, YY. Visualization: SY, YY. Writing: original draft or/and Review & Editing: SY, YY. Final approval of the manuscript: SY, YY.

Fig. 1.
Flowchart of study population selection. T2DM, type 2 diabetes mellitus.
jkan-24109f1.jpg
Table 1.
Association between general characteristics and onset of diabetic complications
Characteristic Total (n=35,804) Onset of diabetic complications
All complications Macrovascular complications Microvascular complications
All CeVD CVD PVD All NEPH NEURO RETINO
n (%) n (%) p n (%) p n (%) p n (%) p n (%) p n (%) p n (%) p n (%) p n (%) p
All 29,205 (81.6) 21,481 (60.0) 6,476 (18.1) 13,935 (38.9) 14,502 (40.5) 24,564 (68.6) 7,929 (22.2) 16,951 (47.3) 14,205 (40.0)
Gender <.001 <.001 <.001 <.001 <.001 <.001 .070 <.001 <.001
 Men 20,120 (56.2) 15,750 (78.3) 11,363 (56.5) 3,214 (16.0) 7,325 (36.4) 7,508 (37.3) 12,997 (64.6) 4,385 (21.8) 8,669 (43.1) 7,190 (35.7)
 Women 15,684 (43.8) 13,455 (85.8) 10,118 (64.5) 3,262 (20.8) 6, 610 (42.1) 6,994 (44.6) 11,567 (73.8) 3,544 (22.6) 8,282 (52.8) 7,015 (44.7)
Age (yr) <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001
 18–29 309 (0.8) 210 (68.0) 101 (32.7) 8 (2.6) 47 (15.2) 79 (25.6) 182 (58.9) 64 (20.7) 104 (33.7) 122 (39.5)
 30–39 2,083 (5.8) 1,415 (67.9) 783 (37.6) 90 (4.3) 415 (19.9) 552 (26.5) 1,219 (58.5) 443 (21.3) 711 (34.1) 690 (33.1)
 40–49 7,362 (20.6) 5,531 (75.1) 3,642 (49.5) 696 (9.5) 2,074 (28.2) 2,622 (35.6) 4,639 (63.0) 1,494 (20.3) 2,942 (40.0) 2,695 (36.6)
 50–59 11,842 (33.1) 9,642 (81.4) 6,917 (58.4) 1,770 (15.0) 4,338 (36.6) 4,741 (40.0) 8,146 (68.8) 2,548 (21.5) 5,573 (47.1) 4,826 (40.8)
 60–69 9,055 (25.3) 7,858 (86.8) 6,243 (69.0) 2,261 (25.0) 4,304 (47.5) 4,166 (46.0) 6,678 (73.8) 2,138 (23.6) 4,841 (53.5) 4,085 (45.1)
 ≥70 5,153 (14.4) 4,549 (88.3) 3,795 (73.7) 1,651 (32.0) 2,757 (53.5) 2,342 (45.5) 3,700 (71.8) 1,242 (24.1) 2,780 (54.0) 1,787 (34.7)
Household income .885 .565 .003 .001 .148 .985 .115 <.001 <.001
 Low 8,500 (23.7) 6,973 (82.0) 5,135 (60.4) 1,494 (17.6) 3,255 (38.3) 3,456 (40.7) 5,839 (68.7) 1,838 (21.6) 4,152 (48.9) 3,258 (38.3)
 Middle 13,426 (37.5) 10,864 (80.9) 7,943 (59.2) 2,346 (17.5) 5,101 (38.0) 5,516 (41.1) 9,195 (68.5) 2,966 (22.1) 6,391 (47.6) 5,324 (39.7)
 High 13,878 (38.8) 11,368 (81.9) 8,403 (60.6) 2,636 (19.0) 5,579 (40.2) 5,530 (39.9) 9,530 (68.7) 3,125 (22.5) 6,408 (46.2) 5,623 (40.5)
CCI score <.001 <.001 <.001 <.001 .521 .002 <.001 <.001 .345
 0 15,396 (43.0) 13,256 (86.1) 9,730 (63.2) 2,848 (18.5) 6,127 (39.8) 6,774 (44.0) 11,239 (73.0) 3,587 (23.3) 7,590 (49.3) 6,636 (43.1)
 1 4,869 (13.6) 4,480 (92.0) 3,530 (72.5) 1,193 (24.5) 2,464 (50.6) 2,405 (49.4) 3,857 (79.2) 1,251 (25.7) 2,839 (58.3) 2,347 (48.2)
 2 9,739 (27.2) 8,385 (86.1) 6,126 (62.9) 1,782 (18.3) 3,886 (39.9) 4,139 (42.5) 7,080 (72.7) 2,357 (24.2) 4,860 (49.9) 4,022 (41.3)
 ≥3 5,800 (16.2) 5,220 (90.0) 4,118 (71.0) 1,363 (23.5) 2,877 (49.6) 2,686 (46.3) 4,443 (76.6) 1,531 (26.4) 3,306 (57.0) 2,541 (43.8)
MPRm (%) .776 .737 .199 .376 .503 .732 .075 .449 <.001
 <80 12,734 (35.6) 10,397 (81.7) 7,625 (59.9) 2,348 (18.4) 4,917 (38.6) 5,128 (40.3) 8,722 (68.5) 2,887 (22.7) 6,063 (47.6) 4,800 (37.7)
 ≥80 23,070 (64.4) 18,808 (81.5) 13,856 (60.1) 4,128 (17.9) 9,018 (39.1) 9,734 (40.6) 15,842 (68.7) 5,042 (21.9) 10,888 (47.2) 9,405 (40.8)
DM duration (yr) <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001
 <5 11,680 (32.6) 8,011 (68.6) 4,415 (37.8) 793 (6.8) 2,404 (20.6) 2,338 (20.0) 5,635 (48.2) 1,319 (11.3) 3,049 (26.1) 2,488 (21.3)
 ≥5, <10 14,655 (40.9) 12,411 (84.7) 9,237 (63.0) 2,540 (17.3) 5,819 (39.7) 5,945 (40.6) 10,638 (72.6) 3,300 (22.5) 7,228 (49.3) 6,038 (41.2)
 ≥10 9,469 (26.5) 8,783 (92.8) 7,829 (82.7) 3,143 (33.2) 5,712 (60.3) 6,219 (65.7) 8,291 (87.6) 3,310 (35.0) 6,674 (70.5) 5,679 (60.0)
Smoking status <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001
 Never 21,705 (60.6) 18,577 (85.6) 14,053 (64.8) 4,550 (21.0) 9,255 (42.6) 9,701 (44.7) 15,913 (73.3) 5,129 (23.6) 11,272 (51.9) 9,502 (43.8)
 Former 4,422 (12.4) 3,087 (69.8) 1,994 (45.1) 450 (10.2) 1,246 (28.2) 1,132 (25.6) 2,439 (55.2) 727 (16.4) 1,441 (32.6) 1,332 (30.1)
 Current 9,677 (27.0) 7,541 (77.9) 5,434 (56.2) 1,476 (15.3) 3,434 (35.5) 3,669 (37.9) 6,212 (64.2) 2,073 (21.4) 4,238 (43.8) 3,371 (34.8)
Duration of smoking (yr)a) <.001 <.001 <.001 <.001 <.001 .001 .019 <.001 .064
 1–9 1,156 (8.2) 873 (75.5) 573 (49.6) 109 (9.4) 350 (30.3) 384 (33.2) 730 (63.1) 235 (20.3) 469 (40.6) 428 (37.0)
 10–19 3,299 (23.4) 2,362 (71.6) 1,531 (46.4) 284 (8.6) 891 (27.0) 1,036 (31.4) 1,950 (59.1) 624 (18.9) 1,194 (36.2) 1,109 (33.6)
 20–29 4,568 (32.4) 3,330 (72.9) 2,252 (49.3) 516 (11.3) 1,380 (30.2) 1,494 (32.7) 2,713 (59.4) 845 (18.5) 1,722 (37.7) 1,480 (32.4)
 ≥30 5,076 (36.0) 4,061 (80.0) 3,076 (60.6) 1,020 (20.1) 2,061 (40.6) 1,893 (37.3) 3,259 (64.2) 1,096 (21.6) 2,289 (45.1) 1,685 (33.2)
Daily smoking amount (packs)a) .001 <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001
 <1 7,190 (51.0) 5,537 (77.0) 3,984 (55.4) 1,122 (15.6) 2,538 (35.3) 2,653 (36.9) 4,544 (63.2) 1,553 (21.6) 3,042 (42.3) 2,509 (34.9)
 ≥1, <2 6,274 (44.5) 4,599 (73.3) 3,112 (49.6) 722 (11.5) 1,939 (30.9) 1,932 (30.8) 3,702 (59.0) 1,129 (18.0) 2,372 (37.8) 1,989 (31.7)
 ≥2 634 (4.5) 495 (78.0) 338 (53.3) 84 (13.2) 206 (32.5) 214 (33.7) 404 (63.6) 117 (18.5) 268 (42.2) 207 (32.6)
Binge drinkingb) .091 .281 .361 .267 .195 .300 .579 .082 .755
 No 5,686 (37.3) 4,316 (75.9) 3,025 (53.2) 2,172 (38.2) 1,848 (32.5) 2,013 (35.4) 3,571 (62.8) 1,171 (20.6) 2,331 (41.0) 2,007 (35.3)
 Yes 9,542 (62.7) 7,357 (77.1) 5,162 (54.1) 1,307 (13.7) 3,187 (33.4) 3,483 (36.5) 6,078 (63.7) 1,927 (20.2) 4,046 (42.4) 3,349 (35.1)
Heavy drinkingb) .296 .133 .222 .451 .604 .087 <.001 .334 <.001
 No 8,124 (54.2) 6,207 (76.4) 4,330 (53.3) 1,105 (13.6) 2,673 (32.9) 2,925 (36.0) 5,199 (64.0) 1,755 (21.6) 3,388 (41.7) 2,982 (36.7)
 Yes 6,855 (45.8) 5,285 (77.1) 3,736 (54.5) 980 (14.3) 2,296 (33.5) 2,495 (36.4) 4,298 (62.7) 1,309 (19.1) 2,913 (42.5) 2,290 (33.4)
Physical activity (times/wk) <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001
 None 13,313 (37.2) 11,527 (86.6) 9,071 (68.1) 3,100 (23.3) 6,077 (45.7) 6,400 (48.1) 9,873 (74.2) 3,329 (25.0) 7,274 (54.6) 5,699 (42.8)
 1–2 8,022 (22.4) 6,516 (81.2) 4,665 (58.2) 1,290 (16.1) 2,979 (37.1) 3,170 (39.5) 5,518 (68.8) 1,769 (22.1) 3,753 (46.8) 3,238 (40.4)
 3–4 6,086 (17.0) 4,657 (76.5) 3,202 (52.6) 827 (13.6) 2,049 (33.7) 2,039 (33.5) 3,860 (63.4) 1,197 (19.7) 2,447 (40.2) 2,277 (37.4)
 ≥5 8,383 (23.4) 6,505 (77.6) 4,543 (54.2) 1,259 (15.0) 2,830 (33.8) 2,893 (34.5) 5,313 (63.4) 1,634 (19.5) 3,477 (41.5) 2,991 (35.7)

Values are presented as number of frequency (row %), calculated as (patients with the complication/total patients in the category)×100, rounded to one decimal place. Individual complication counts include overlaps, while all complications exclude them.

CCI, Charlson comorbidity index; CeVD, cerebrovascular disease; CVD, cardiovascular disease; DM, diabetes mellitus; MPRm, medication possession ratio modified; NEPH, nephropathy; NEURO, neuropathy; PVD, peripheral vascular disease; RETINO, retinopathy.

a)Total number for this group=39.4% of the total (35,804). b)Non-drinkers were excluded.

Table 2.
Incidence of diabetic complications by smoking status, duration, and amount
All complication Macrovascular complications Microvascular complications
All CeVD CVD PVD All NEPH NEURO RETINO
Adj.HR (95% CI) p Adj.HR (95% CI) p Adj.HR (95% CI) p Adj.HR (95% CI) p Adj.HR (95% CI) p Adj.HR (95% CI) p Adj.HR (95% CI) p Adj.HR (95% CI) p Adj.HR (95% CI) p
Smoking status
 Never Ref Ref Ref Ref Ref Ref Ref Ref Ref
 Former 2.09 (1.99–2.19) <.001 1.60 (1.49–1.66) <.001 1.07 (0.96–1.19) .220 1.39 (1.30–1.49) <.001 1.10 (1.03–1.19) <.001 1.81 (1.72–1.91) <.001 1.27 (1.16–1.39) <.001 1.40 (1.31–1.49) <.001 1.49 (1.39–1.60) <.001
 Current 1.21 (1.17–1.25) <.001 1.10 (1.08–1.17) <.001 1.04 (0.96–1.11) .324 1.11 (1.06–1.16) <.001 1.04 (0.99–1.09) .084 1.16 (1.11–1.20) <.001 1.06 (0.99–1.13) .081 1.10 (1.08–1.18) <.001 1.05 (1.00–1.10) .056
Duration of smoking (yr)
 Never Ref Ref Ref Ref Ref Ref Ref Ref Ref
 1–9 1.30 (1.17–1.35) <.001 1.02 (0.94–1.11) .650 0.68 (0.56–0.83) <.001 0.96 (0.86–1.07) .435 0.97 (0.88–1.08) .635 1.18 (1.09–1.27) <.001 1.06 (0.92–1.21) .410 1.05 (0.96–1.16) .280 1.16 (1.05–1.28) <.001
 10–19 1.30 (1.20–1.33) <.001 1.05 (0.99–1.11) .120 0.69 (0.61–0.78) <.001 0.96 (0.89–1.04) .340 0.95 (0.88–1.02) .162 1.18 (1.12–1.25) <.001 1.05 (0.95–1.15) .337 1.03 (0.96–1.10) .467 1.09 (1.02–1.17) <.001
 20–29 1.40 (1.33–1.45) <.001 1.22 (1.15–1.28) <.001 0.97 (0.87–1.07) .509 1.16 (1.09–1.24) <.001 1.06 (0.99–1.12) .095 1.29 (1.23–1.36) <.001 1.07 (0.98–1.16) .125 1.15 (1.08–1.22) <.001 1.13 (1.06–1.20) <.001
 ≥30 1.40 (1.38–1.49) <.001 1.35 (1.29–1.42) <.001 1.36 (1.26–1.48) <.001 1.34 (1.27–1.42) <.001 1.15 (1.08–1.22) <.001 1.36 (1.30–1.42) <.001 1.18 (1.10–1.28) <.001 1.35 (1.28–1.42) <.001 1.18 (1.11–1.25) <.001
Daily smoking amount (packs)
 Never Ref Ref Ref Ref Ref Ref Ref Ref Ref
 <1 1.20 (1.14–1.23) <.001 1.11 (1.06–1.16) <.001 1.12 (1.08–1.17) <.001 1.09 (1.03–1.14) <.001 1.04 (0.99–1.09) .133 1.12 (1.08–1.17) <.001 1.05 (1.00–1.11) .075 1.08 (1.03–1.14) <.001 1.05 (1.00–1.11) .075
 ≥1, <2 1.70 (1.61–1.74) <.001 1.37 (1.31–1.44) <.001 1.53 (1.47–1.60) <.001 1.30 (1.23–1.38) <.001 1.08 (1.02–1.14) <.001 1.53 (1.47–1.60) <.001 1.28 (1.21–1.36) <.001 1.33 (1.26–1.40) <.001 1.28 (1.21–1.36) <.001
 ≥2 1.90 (1.72–2.08) <.001 1.46 (1.30–1.64) <.001 1.78 (1.60–1.98) <.001 1.33 (1.15–1.53) <.001 1.11 (0.96–1.28) .150 1.78 (1.60–1.98) <.001 1.35 (1.17–1.56) <.001 1.51 (1.33–1.71) <.001 1.35 (1.17–1.56) <.001

Adjusted for gender, age, household income, CCI score, MPRm, heavy drinking, and physical activity.

Adj.HR, adjusted hazard ratio; CCI, Charlson comorbidity index; CeVD, cerebrovascular disease; CI, confidence interval; CVD, cardiovascular disease; MPRm, medication possession ratio modified; NEPH, nephropathy; NEURO, neuropathy; PVD, peripheral vascular disease; Ref, reference; RETINO, retinopathy.

Appendix 1.
Exclusion strategy based on the timing of the onset of diabetes and diabetic complications.
jkan-24109f2.jpg

Figure & Data

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      The impact of smoking on diabetic complications: data from the National Health Insurance Service-National Health Screening Cohort (2002–2019)
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      Fig. 1. Flowchart of study population selection. T2DM, type 2 diabetes mellitus.

      Fig. 1.

      The impact of smoking on diabetic complications: data from the National Health Insurance Service-National Health Screening Cohort (2002–2019)
      Characteristic Total (n=35,804) Onset of diabetic complications
      All complications Macrovascular complications Microvascular complications
      All CeVD CVD PVD All NEPH NEURO RETINO
      n (%) n (%) p n (%) p n (%) p n (%) p n (%) p n (%) p n (%) p n (%) p n (%) p
      All 29,205 (81.6) 21,481 (60.0) 6,476 (18.1) 13,935 (38.9) 14,502 (40.5) 24,564 (68.6) 7,929 (22.2) 16,951 (47.3) 14,205 (40.0)
      Gender <.001 <.001 <.001 <.001 <.001 <.001 .070 <.001 <.001
       Men 20,120 (56.2) 15,750 (78.3) 11,363 (56.5) 3,214 (16.0) 7,325 (36.4) 7,508 (37.3) 12,997 (64.6) 4,385 (21.8) 8,669 (43.1) 7,190 (35.7)
       Women 15,684 (43.8) 13,455 (85.8) 10,118 (64.5) 3,262 (20.8) 6, 610 (42.1) 6,994 (44.6) 11,567 (73.8) 3,544 (22.6) 8,282 (52.8) 7,015 (44.7)
      Age (yr) <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001
       18–29 309 (0.8) 210 (68.0) 101 (32.7) 8 (2.6) 47 (15.2) 79 (25.6) 182 (58.9) 64 (20.7) 104 (33.7) 122 (39.5)
       30–39 2,083 (5.8) 1,415 (67.9) 783 (37.6) 90 (4.3) 415 (19.9) 552 (26.5) 1,219 (58.5) 443 (21.3) 711 (34.1) 690 (33.1)
       40–49 7,362 (20.6) 5,531 (75.1) 3,642 (49.5) 696 (9.5) 2,074 (28.2) 2,622 (35.6) 4,639 (63.0) 1,494 (20.3) 2,942 (40.0) 2,695 (36.6)
       50–59 11,842 (33.1) 9,642 (81.4) 6,917 (58.4) 1,770 (15.0) 4,338 (36.6) 4,741 (40.0) 8,146 (68.8) 2,548 (21.5) 5,573 (47.1) 4,826 (40.8)
       60–69 9,055 (25.3) 7,858 (86.8) 6,243 (69.0) 2,261 (25.0) 4,304 (47.5) 4,166 (46.0) 6,678 (73.8) 2,138 (23.6) 4,841 (53.5) 4,085 (45.1)
       ≥70 5,153 (14.4) 4,549 (88.3) 3,795 (73.7) 1,651 (32.0) 2,757 (53.5) 2,342 (45.5) 3,700 (71.8) 1,242 (24.1) 2,780 (54.0) 1,787 (34.7)
      Household income .885 .565 .003 .001 .148 .985 .115 <.001 <.001
       Low 8,500 (23.7) 6,973 (82.0) 5,135 (60.4) 1,494 (17.6) 3,255 (38.3) 3,456 (40.7) 5,839 (68.7) 1,838 (21.6) 4,152 (48.9) 3,258 (38.3)
       Middle 13,426 (37.5) 10,864 (80.9) 7,943 (59.2) 2,346 (17.5) 5,101 (38.0) 5,516 (41.1) 9,195 (68.5) 2,966 (22.1) 6,391 (47.6) 5,324 (39.7)
       High 13,878 (38.8) 11,368 (81.9) 8,403 (60.6) 2,636 (19.0) 5,579 (40.2) 5,530 (39.9) 9,530 (68.7) 3,125 (22.5) 6,408 (46.2) 5,623 (40.5)
      CCI score <.001 <.001 <.001 <.001 .521 .002 <.001 <.001 .345
       0 15,396 (43.0) 13,256 (86.1) 9,730 (63.2) 2,848 (18.5) 6,127 (39.8) 6,774 (44.0) 11,239 (73.0) 3,587 (23.3) 7,590 (49.3) 6,636 (43.1)
       1 4,869 (13.6) 4,480 (92.0) 3,530 (72.5) 1,193 (24.5) 2,464 (50.6) 2,405 (49.4) 3,857 (79.2) 1,251 (25.7) 2,839 (58.3) 2,347 (48.2)
       2 9,739 (27.2) 8,385 (86.1) 6,126 (62.9) 1,782 (18.3) 3,886 (39.9) 4,139 (42.5) 7,080 (72.7) 2,357 (24.2) 4,860 (49.9) 4,022 (41.3)
       ≥3 5,800 (16.2) 5,220 (90.0) 4,118 (71.0) 1,363 (23.5) 2,877 (49.6) 2,686 (46.3) 4,443 (76.6) 1,531 (26.4) 3,306 (57.0) 2,541 (43.8)
      MPRm (%) .776 .737 .199 .376 .503 .732 .075 .449 <.001
       <80 12,734 (35.6) 10,397 (81.7) 7,625 (59.9) 2,348 (18.4) 4,917 (38.6) 5,128 (40.3) 8,722 (68.5) 2,887 (22.7) 6,063 (47.6) 4,800 (37.7)
       ≥80 23,070 (64.4) 18,808 (81.5) 13,856 (60.1) 4,128 (17.9) 9,018 (39.1) 9,734 (40.6) 15,842 (68.7) 5,042 (21.9) 10,888 (47.2) 9,405 (40.8)
      DM duration (yr) <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001
       <5 11,680 (32.6) 8,011 (68.6) 4,415 (37.8) 793 (6.8) 2,404 (20.6) 2,338 (20.0) 5,635 (48.2) 1,319 (11.3) 3,049 (26.1) 2,488 (21.3)
       ≥5, <10 14,655 (40.9) 12,411 (84.7) 9,237 (63.0) 2,540 (17.3) 5,819 (39.7) 5,945 (40.6) 10,638 (72.6) 3,300 (22.5) 7,228 (49.3) 6,038 (41.2)
       ≥10 9,469 (26.5) 8,783 (92.8) 7,829 (82.7) 3,143 (33.2) 5,712 (60.3) 6,219 (65.7) 8,291 (87.6) 3,310 (35.0) 6,674 (70.5) 5,679 (60.0)
      Smoking status <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001
       Never 21,705 (60.6) 18,577 (85.6) 14,053 (64.8) 4,550 (21.0) 9,255 (42.6) 9,701 (44.7) 15,913 (73.3) 5,129 (23.6) 11,272 (51.9) 9,502 (43.8)
       Former 4,422 (12.4) 3,087 (69.8) 1,994 (45.1) 450 (10.2) 1,246 (28.2) 1,132 (25.6) 2,439 (55.2) 727 (16.4) 1,441 (32.6) 1,332 (30.1)
       Current 9,677 (27.0) 7,541 (77.9) 5,434 (56.2) 1,476 (15.3) 3,434 (35.5) 3,669 (37.9) 6,212 (64.2) 2,073 (21.4) 4,238 (43.8) 3,371 (34.8)
      Duration of smoking (yr)a) <.001 <.001 <.001 <.001 <.001 .001 .019 <.001 .064
       1–9 1,156 (8.2) 873 (75.5) 573 (49.6) 109 (9.4) 350 (30.3) 384 (33.2) 730 (63.1) 235 (20.3) 469 (40.6) 428 (37.0)
       10–19 3,299 (23.4) 2,362 (71.6) 1,531 (46.4) 284 (8.6) 891 (27.0) 1,036 (31.4) 1,950 (59.1) 624 (18.9) 1,194 (36.2) 1,109 (33.6)
       20–29 4,568 (32.4) 3,330 (72.9) 2,252 (49.3) 516 (11.3) 1,380 (30.2) 1,494 (32.7) 2,713 (59.4) 845 (18.5) 1,722 (37.7) 1,480 (32.4)
       ≥30 5,076 (36.0) 4,061 (80.0) 3,076 (60.6) 1,020 (20.1) 2,061 (40.6) 1,893 (37.3) 3,259 (64.2) 1,096 (21.6) 2,289 (45.1) 1,685 (33.2)
      Daily smoking amount (packs)a) .001 <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001
       <1 7,190 (51.0) 5,537 (77.0) 3,984 (55.4) 1,122 (15.6) 2,538 (35.3) 2,653 (36.9) 4,544 (63.2) 1,553 (21.6) 3,042 (42.3) 2,509 (34.9)
       ≥1, <2 6,274 (44.5) 4,599 (73.3) 3,112 (49.6) 722 (11.5) 1,939 (30.9) 1,932 (30.8) 3,702 (59.0) 1,129 (18.0) 2,372 (37.8) 1,989 (31.7)
       ≥2 634 (4.5) 495 (78.0) 338 (53.3) 84 (13.2) 206 (32.5) 214 (33.7) 404 (63.6) 117 (18.5) 268 (42.2) 207 (32.6)
      Binge drinkingb) .091 .281 .361 .267 .195 .300 .579 .082 .755
       No 5,686 (37.3) 4,316 (75.9) 3,025 (53.2) 2,172 (38.2) 1,848 (32.5) 2,013 (35.4) 3,571 (62.8) 1,171 (20.6) 2,331 (41.0) 2,007 (35.3)
       Yes 9,542 (62.7) 7,357 (77.1) 5,162 (54.1) 1,307 (13.7) 3,187 (33.4) 3,483 (36.5) 6,078 (63.7) 1,927 (20.2) 4,046 (42.4) 3,349 (35.1)
      Heavy drinkingb) .296 .133 .222 .451 .604 .087 <.001 .334 <.001
       No 8,124 (54.2) 6,207 (76.4) 4,330 (53.3) 1,105 (13.6) 2,673 (32.9) 2,925 (36.0) 5,199 (64.0) 1,755 (21.6) 3,388 (41.7) 2,982 (36.7)
       Yes 6,855 (45.8) 5,285 (77.1) 3,736 (54.5) 980 (14.3) 2,296 (33.5) 2,495 (36.4) 4,298 (62.7) 1,309 (19.1) 2,913 (42.5) 2,290 (33.4)
      Physical activity (times/wk) <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001
       None 13,313 (37.2) 11,527 (86.6) 9,071 (68.1) 3,100 (23.3) 6,077 (45.7) 6,400 (48.1) 9,873 (74.2) 3,329 (25.0) 7,274 (54.6) 5,699 (42.8)
       1–2 8,022 (22.4) 6,516 (81.2) 4,665 (58.2) 1,290 (16.1) 2,979 (37.1) 3,170 (39.5) 5,518 (68.8) 1,769 (22.1) 3,753 (46.8) 3,238 (40.4)
       3–4 6,086 (17.0) 4,657 (76.5) 3,202 (52.6) 827 (13.6) 2,049 (33.7) 2,039 (33.5) 3,860 (63.4) 1,197 (19.7) 2,447 (40.2) 2,277 (37.4)
       ≥5 8,383 (23.4) 6,505 (77.6) 4,543 (54.2) 1,259 (15.0) 2,830 (33.8) 2,893 (34.5) 5,313 (63.4) 1,634 (19.5) 3,477 (41.5) 2,991 (35.7)
      All complication Macrovascular complications Microvascular complications
      All CeVD CVD PVD All NEPH NEURO RETINO
      Adj.HR (95% CI) p Adj.HR (95% CI) p Adj.HR (95% CI) p Adj.HR (95% CI) p Adj.HR (95% CI) p Adj.HR (95% CI) p Adj.HR (95% CI) p Adj.HR (95% CI) p Adj.HR (95% CI) p
      Smoking status
       Never Ref Ref Ref Ref Ref Ref Ref Ref Ref
       Former 2.09 (1.99–2.19) <.001 1.60 (1.49–1.66) <.001 1.07 (0.96–1.19) .220 1.39 (1.30–1.49) <.001 1.10 (1.03–1.19) <.001 1.81 (1.72–1.91) <.001 1.27 (1.16–1.39) <.001 1.40 (1.31–1.49) <.001 1.49 (1.39–1.60) <.001
       Current 1.21 (1.17–1.25) <.001 1.10 (1.08–1.17) <.001 1.04 (0.96–1.11) .324 1.11 (1.06–1.16) <.001 1.04 (0.99–1.09) .084 1.16 (1.11–1.20) <.001 1.06 (0.99–1.13) .081 1.10 (1.08–1.18) <.001 1.05 (1.00–1.10) .056
      Duration of smoking (yr)
       Never Ref Ref Ref Ref Ref Ref Ref Ref Ref
       1–9 1.30 (1.17–1.35) <.001 1.02 (0.94–1.11) .650 0.68 (0.56–0.83) <.001 0.96 (0.86–1.07) .435 0.97 (0.88–1.08) .635 1.18 (1.09–1.27) <.001 1.06 (0.92–1.21) .410 1.05 (0.96–1.16) .280 1.16 (1.05–1.28) <.001
       10–19 1.30 (1.20–1.33) <.001 1.05 (0.99–1.11) .120 0.69 (0.61–0.78) <.001 0.96 (0.89–1.04) .340 0.95 (0.88–1.02) .162 1.18 (1.12–1.25) <.001 1.05 (0.95–1.15) .337 1.03 (0.96–1.10) .467 1.09 (1.02–1.17) <.001
       20–29 1.40 (1.33–1.45) <.001 1.22 (1.15–1.28) <.001 0.97 (0.87–1.07) .509 1.16 (1.09–1.24) <.001 1.06 (0.99–1.12) .095 1.29 (1.23–1.36) <.001 1.07 (0.98–1.16) .125 1.15 (1.08–1.22) <.001 1.13 (1.06–1.20) <.001
       ≥30 1.40 (1.38–1.49) <.001 1.35 (1.29–1.42) <.001 1.36 (1.26–1.48) <.001 1.34 (1.27–1.42) <.001 1.15 (1.08–1.22) <.001 1.36 (1.30–1.42) <.001 1.18 (1.10–1.28) <.001 1.35 (1.28–1.42) <.001 1.18 (1.11–1.25) <.001
      Daily smoking amount (packs)
       Never Ref Ref Ref Ref Ref Ref Ref Ref Ref
       <1 1.20 (1.14–1.23) <.001 1.11 (1.06–1.16) <.001 1.12 (1.08–1.17) <.001 1.09 (1.03–1.14) <.001 1.04 (0.99–1.09) .133 1.12 (1.08–1.17) <.001 1.05 (1.00–1.11) .075 1.08 (1.03–1.14) <.001 1.05 (1.00–1.11) .075
       ≥1, <2 1.70 (1.61–1.74) <.001 1.37 (1.31–1.44) <.001 1.53 (1.47–1.60) <.001 1.30 (1.23–1.38) <.001 1.08 (1.02–1.14) <.001 1.53 (1.47–1.60) <.001 1.28 (1.21–1.36) <.001 1.33 (1.26–1.40) <.001 1.28 (1.21–1.36) <.001
       ≥2 1.90 (1.72–2.08) <.001 1.46 (1.30–1.64) <.001 1.78 (1.60–1.98) <.001 1.33 (1.15–1.53) <.001 1.11 (0.96–1.28) .150 1.78 (1.60–1.98) <.001 1.35 (1.17–1.56) <.001 1.51 (1.33–1.71) <.001 1.35 (1.17–1.56) <.001
      Table 1. Association between general characteristics and onset of diabetic complications

      Values are presented as number of frequency (row %), calculated as (patients with the complication/total patients in the category)×100, rounded to one decimal place. Individual complication counts include overlaps, while all complications exclude them.

      CCI, Charlson comorbidity index; CeVD, cerebrovascular disease; CVD, cardiovascular disease; DM, diabetes mellitus; MPRm, medication possession ratio modified; NEPH, nephropathy; NEURO, neuropathy; PVD, peripheral vascular disease; RETINO, retinopathy.

      a)Total number for this group=39.4% of the total (35,804). b)Non-drinkers were excluded.

      Table 2. Incidence of diabetic complications by smoking status, duration, and amount

      Adjusted for gender, age, household income, CCI score, MPRm, heavy drinking, and physical activity.

      Adj.HR, adjusted hazard ratio; CCI, Charlson comorbidity index; CeVD, cerebrovascular disease; CI, confidence interval; CVD, cardiovascular disease; MPRm, medication possession ratio modified; NEPH, nephropathy; NEURO, neuropathy; PVD, peripheral vascular disease; Ref, reference; RETINO, retinopathy.

      Table 1.

      Table 2.

      J Korean Acad Nurs : Journal of Korean Academy of Nursing
      © Korean Society of Nursing Science.
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