INTRODUCTION

Diabetes is a chronic metabolic disease characterized by hyperglycemia that can seriously damage macrovascular and microvascular systems over time [1]. Sleep disturbances are commonly reported among patients with diabetes and are associated with both an increased risk of developing the disease and a comparatively poor prognosis [2]. Uncontrolled diabetes, evidenced by high levels of glycated hemoglobin (HbA1c) or nocturnal glycemic variability, is associated with various sleep-related issues; these include abnormal sleep duration, circadian rhythm sleep-wake disorders, insomnia, and restless leg syndrome [3,4]. Guidelines from the American Association of Clinical Endocrinology strongly recommend regular monitoring of HbA1c levels and other complications of diabetes to improve long-term health outcomes [5]. Similarly, the American Diabetes Association recommends an annual assessment of complications and common comorbidities, such as chronic kidney disease or retinopathy, in patients with diabetes [6].

Unfortunately, adherence to diabetes management measures among Koreans is low. For instance, while recommendations indicate that HbA1c levels should be tested twice annually, only about one-third of the diabetic population in Korea follows this guideline [7]. This test adherence rate is considerably lower than the 70% observed in the United States and Germany [8,9]. Furthermore, among Korean patients who have been recently diagnosed with diabetes, approximately two-thirds do not undergo HbA1c testing even once per year [10]. Regarding screening for diabetic complications, in a prior study, only about one-quarter of Korean patients with diabetes engaged in annual follow-up examinations [11].

Previous studies have demonstrated that non-adherence to management guidelines is linked to an elevated risk of morbidity and mortality. Specifically, undergoing HbA1c testing less frequently than recommended has been associated with poor diabetes control and a greater risk of complications such as ischemic heart disease and chronic kidney disease. These complications can lead to a greater likelihood of hospitalization and death [8-10,12-14]. However, to our knowledge, no previous studies have utilized real-world data from community-dwelling patients with diabetes to assess the impact of non-adherence to diabetes management on poor sleep quality.

In the present study, we compared the sleep quality of patients with diabetes based on their adherence to diabetes management guidelines and evaluated the impact of adherence on sleep quality.

METHODS

Study Design

In this cross-sectional study, we investigated the association between adherence to diabetes management guidelines and sleep quality, employing data from the Korea Community Health Survey 2018 (KCHS-18). The KCHS is an annual survey that gathers information from 255 administrative districts across Korea. Participants in the KCHS are Korean residents aged 19 years or older as of July 1 of the survey year. Data for the KCHS-18 were collected between August 2018 and October of 2018. Participants from every region of Korea were included in the KCHS-18, providing a representative sample of the Korean population [15].

Participants and Data Collection

Based on surveys of 228 340 respondents, 72 503 individuals aged 65 years or older were assessed for eligibility. Of these, 4257 were excluded from the study due to non-response or missing values for variables related to diabetes status, sleep quality, and/or potential confounders. Most of the non-responses or missing values pertained to the Pittsburgh Sleep Quality Index (PSQI; n =1526) or household income (n =2635). Ultimately, 68 246 observations were selected for analysis, representing a response rate of 94.1% (Supplemental Material 1).

The participants were divided into 3 groups based on their diabetes diagnosis and management status: no diabetes, diabetes with rigorous adherence, and diabetes without rigorous adherence. Participants were defined as having diabetes if they self-reported a diagnosis made by a doctor. Because the KCHS-18 is a community survey primarily dependent on participant self-reporting, direct indicators of diabetes management, such as HbA1c or blood glucose levels, were not available. The “no diabetes” group consisted of individuals without a diabetes diagnosis, who were presumed to have blood glucose levels within the normal range. The rigorous adherence group comprised patients with diabetes who had undergone all recommended tests for diabetes management (at least 2 HbA1c tests, 1 fundus examination, and 1 urine microalbuminuria test in the past year) and had received diabetes management education from a medical professional at least once. Patients with diabetes who did not meet these criteria were classified as having diabetes without rigorous adherence. We also explored the potential impact of the degree of adherence to diabetes management on sleep quality. We defined 2 subgroups—moderate adherence and non-adherence—and assessed their likelihood of reporting poor sleep quality and sleep disturbances compared to the participants without diabetes. The moderate adherence group consisted of patients with diabetes who had completed at least 2 HbA1c tests in the previous year and had either undergone tests related to diabetes complications (fundus examination and urine microalbuminuria tests) or received diabetes management education from a medical professional. The non-adherence group included patients with the disease who received 1 or no HbA1c tests in the past year and had not undergone other tests or received diabetes management education.

The outcome variables of this study included poor overall sleep quality and various sleep disturbance events as measured by the PSQI. These disturbances included sleep fragmentation, nocturia, pain during sleep, difficulty falling asleep, and bad dreams, all of which were suspected to be linked to diabetes [3,16]. The PSQI assesses self-reported overall sleep quality over the course of 1 month, using 7 components each scored on a scale from 0 to 3 [17]. A PSQI score of 5 or higher is considered indicative of poor overall sleep quality. Additionally, the PSQI measures the frequency of various sleep-disrupting events within the previous month, with 4 possible intervals: not during the past month, less than once a week, once or twice a week, and 3 or more times a week. For this analysis, to estimate the association between non-adherence to diabetes management guidelines and regular sleep disturbance, a “sleep disturbance event” was defined as one with a frequency of at least once or twice a week.

To estimate the independent effect of diabetes management status on the prevalence of poor overall sleep quality and sleep disturbance events, we considered potential confounders in the analysis. These included age, sex, area of residence, household income, hypertension status, current smoking, binge drinking, physical activity, oral health, and depression. For household income, participants were divided into 3 groups based on intervals of 1.5 million Korean won (KRW, where approximately 1100 KRW=1 USD in 2024): <1.5 million KRW per month (low), 1.5-3.0 million KRW per month (middle), and ≥3.0 million KRW per month (high). Hypertension status was determined using participants’ self-reported diagnosis by a doctor. Current smoking status was classified as yes or no. For binge drinking, a classification of “yes” was assigned if the participant consumed 5 or more drinks per occasion for male and 3 or more drinks per occasion for female. The threshold for physical activity was set at a minimum of 30 minutes of walking on at least 5 days per week. Oral health was self-reported, with responses of “poor” and “very poor” grouped as “poor” for the analysis, while “normal,” “good,” and “very good” were collectively considered “not poor.” Depression status was assessed using the Patient Health Questionnaire-9 (PHQ-9). Participants with PHQ-9 scores of 10 or higher were categorized as having depression.

To explore the potential impact of non-adherence to management guidelines on sleep quality in the early stages of diabetes, participants were stratified by the duration of diabetes. The cut-off for disease duration was determined by calculating the weighted gross median duration among all participants with diabetes, which was found to be 9.7 years. Accordingly, participants were divided into 2 groups: the earlier stage (characterized by a diabetes duration no greater than the median) and the later stage (defined as a duration exceeding the median).

Statistical Analysis

To compare general characteristics between groups, the frequency and percentage of variables were measured. Percentages were calculated using the weighted values from the KCHS-18 database to estimate the prevalence of poor overall sleep quality and potential confounders in the general Korean population. To identify significant differences in general characteristics based on adherence to diabetes management guidelines, analysis of variance was employed for continuous variables and the chi-square test for categorical variables. Univariate logistic regression was used to examine the association between diabetes management status and sleep quality, including its components. Multivariate logistic regression was then applied to assess the independent effect of diabetes management on the prevalence of poor overall sleep quality and its components, after adjusting for potential confounders. To control for confounders, stratification and multivariable analysis were used. For a more detailed analysis, participants with diabetes were divided into 2 groups based on the duration of the condition. Multivariable analysis was used to control for other potential confounders. Variables that showed significant differences between groups, as well as potential confounders, were selected for analysis.

SAS version 9.4 (SAS Institute Inc., Cary, NC, USA) was used for this study. A complex sample design was employed for the statistical analysis. The statistical significance level was set at p-value <0.05.

Ethics Statement

The Institutional Review Board of the Catholic University of Korea approved this study (IRB No. MC24ZISI0090).

RESULTS

General Characteristics

Among 68 246 participants, 14 354 were diagnosed with diabetes; of these, 934 adhered to diabetes management guidelines, while 13 420 did not. Overall, patients in the rigorous adherence group reported a longer duration of disease. Furthermore, those displaying rigorous adherence were more likely to have a healthy lifestyle than those without rigorous adherence. Specifically, patients engaged in rigorous adherence were less inclined to smoke or engage in binge drinking and more likely to participate in physical activity (Table 1).

The lack of rigorous adherence was associated with a higher prevalence of poor overall sleep quality (51.8%) compared to rigorous adherence (48.9%) and no diabetes (48.0%). Additionally, patients not exhibiting rigorous adherence exhibited higher rates of sleep fragmentation, nocturia, pain during sleep, and difficulty falling asleep than both individuals without diabetes and patients engaged in rigorous adherence (Table 2).

Compared with participants without diabetes, patients with diabetes without rigorous management were more likely to report poor overall sleep quality (adjusted odds ratio [aOR], 1.09; 95% confidence interval [CI], 1.04 to 1.13). Furthermore, these patients were more likely to experience sleep fragmentation (aOR, 1.13; 95% CI, 1.08 to 1.17), nocturia (aOR, 1.25; 95% CI, 1.20 to 1.31), pain during sleep (aOR, 1.09; 95% CI, 1.04 to 1.15), and difficulty falling asleep (aOR, 1.09; 95% CI, 1.05 to 1.14), again relative to individuals who did not have diabetes (Table 3).

Among patients in the earlier stage of diabetes, those lacking rigorous adherence to management were more likely to report poor overall sleep quality (aOR, 1.06; 95% CI, 1.00 to 1.18), sleep fragmentation (aOR, 1.14; 95% CI, 1.08 to 1.20), nocturia (aOR, 1.23; 95% CI, 1.16 to 1.31), and difficulty falling asleep (aOR, 1.07; 95% CI, 1.01 to 1.14) compared to participants without diabetes. In the later stage, patients without rigorous adherence also displayed higher odds of reporting all sleep disturbance events compared to those without diabetes. In contrast, the rigorous adherence group did not exhibit a significantly greater likelihood of reporting any of the assessed sleep disturbance events compared to the no-diabetes group, regardless of the stage of disease (Table 4).

Unlike the group with rigorous adherence to diabetes management, those with moderate adherence were significantly more likely to report overall poor sleep quality (aOR, 1.18; 95% CI, 1.03 to 1.35) and nocturia (aOR, 1.26; 95% CI, 1.09 to 1.46) than the group without diabetes. Similarly, the non-adherence group was more likely to report poor overall sleep quality and a higher frequency of assessed sleep disturbances, with the exception of bad dreams, relative to participants without diabetes (Table 5).

DISCUSSION

Among 14 354 patients with diabetes, approximately 6.5% had received proper education on diabetes and regularly visited clinics to manage the disease. This suggests that only a small fraction of Korean patients with diabetes complied with relevant management guidelines. While patients exhibiting rigorous adherence reported a longer average duration of disease, they were less likely than those without rigorous adherence to experience sleep disturbances. Additionally, smaller proportions of the rigorous adherence group smoked, binge drank, or were physically inactive compared to those lacking such adherence, indicating that the patients engaged in rigorous adherence also maintained healthier lifestyles.

Regular assessment of HbA1c levels, which are indicative of long-term complication risk as well as acute and chronic complications of diabetes, enables patients and physicians to collaboratively devise a treatment plan and lifestyle modifications that can improve disease outcomes and quality of life [5,6]. Poor glycemic control, as determined by HbA1c and fasting blood glucose levels, is associated with poor sleep quality [18,19]. Sleep deprivation stemming from poor sleep quality can trigger increased plasma glucose levels and high insulin resistance due to the elevated secretion of catecholamines and cortisol, which in turn heightens the risk of cardiovascular diseases and mortality [19,20]. Patients with diabetes are more prone to sleep disorders such as insomnia, sleep apnea syndrome, and sleep-related movement disorders than the general population. Such disorders make falling and staying asleep challenging for these patients and contribute to a greater risk of diabetic retinopathy, nephropathy, and neuropathy [3,18,21,22]. The relationship between poor sleep and diabetes may be bidirectional, suggesting a vicious cycle. Thus, patients with diabetes may require more stringent sleep management to mitigate potential risks [3,20].

In this study, patients who did not rigorously adhere to diabetes management guidelines were significantly more likely to experience various sleep disturbances at least once a week compared to individuals without diabetes. Furthermore, patients without rigorous adherence were 9% more likely to report poor overall sleep quality compared with the same group. The sleep disturbance events more frequently reported by the non-adherence group may be linked to uncontrolled diabetes and its complications. For instance, those lacking rigorous adherence reported more frequent nocturia and sleep fragmentation, likely caused by diabetic nephropathy [23]. Compared to those who rigorously adhered to treatment, those who did not do so experienced more difficulty falling asleep, a problem associated with uncontrolled high blood sugar levels at night [24]. Conversely, hypoglycemia can lead to vivid dreams or nightmares [25] and is more common among patients with diabetes who use insulin to manage their blood glucose levels [26]. However, in the treatment of type 2 diabetes—the most prevalent form of the disease—insulin is typically prescribed only when other anti-hyperglycemic treatments are unsuccessful [5]. Although prescription data for KCHS-18 participants were not available, most patients with diabetes in this study may have been using non-insulin medications to control their blood glucose levels. Sleep-related movement disorders, such as restless leg syndrome, which causes aching pain, or periodic limb movement disorder, which leads to repetitive cramping or jerking, are more common in patients with diabetes—particularly those with nephropathy or retinopathy—compared to the general population [3].

Notably, overall sleep quality tended to deteriorate, and sleep disturbances became more frequent, among all patients with diabetes as the disease duration increased. However, those not engaged in rigorous adherence were more prone to experiencing poor sleep quality and frequent sleep disturbances, even in the earlier stage of the disease. Regular monitoring of diabetes and associated complications may enable patients and their physicians to delay disease progression for an extended period.

Our analysis also demonstrated that partial adherence to diabetes management protocols does not provide adequate protection against the poor sleep quality and increased frequency of sleep disturbances associated with diabetes. Health policies should promote not only regular blood glucose testing but also participation in diabetes management education and comprehensive testing for diabetes, which could improve the quality of life for patients with diabetes.

The present study had several limitations. First, as the KCHS-18 relies on self-reported data, we could not verify whether adherence to diabetes management guidelines indeed resulted in normal blood glucose levels. Regular evaluation and examination of patients with diabetes may provide more opportunities for professional feedback on diabetes management and timely medical intervention. Second, clinical measurement data were not available in the KCHS-18 results. Access to relevant clinical information, such as HbA1c levels, microalbumin levels, or fundus examination findings, could have benefited this study. Future research on diabetes management should consider incorporating such clinical parameters into the analysis. Third, the cross-sectional nature of this study precluded the assessment of the effects of changes in management status or variations in sleep quality over time.

This study utilized a nationally representative sample and accounted for a variety of potential confounders, ensuring that the results are reflective of the entire community-dwelling Korean population. Moreover, diabetes management was assessed not only through regular HbA1c testing but also by considering tests for complications and diabetes management education as independent variables.

The findings of this study indicate that most Korean older adults with diabetes did not rigorously adhere to diabetes management guidelines. Patients exhibiting such non-adherence were more likely to experience poor overall sleep quality and frequent sleep disturbances than the community-dwelling population without diabetes. Strategies that promote engagement in diabetes monitoring are necessary to improve the quality of life of individuals with diabetes.

Supplemental Materials

Notes

Conflict of Interest

The authors have no conflicts of interest associated with the material presented in this paper.

Funding

None.

Acknowledgements

None.

Author Contributions

Conceptualization: Hwang HA, Jeong H, Yim HW. Data curation: Hwang HA. Formal analysis: Hwang HA. Funding acquisition: None. Methodology: Hwang HA, Jeong H, Yim HW. Project administration: Jeong H, Yim HW. Visualization: Hwang HA. Writing – original draft: Hwang HA. Writing – review & editing: Jeong H, Yim HW.

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Figure & Data

References

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