A Population-Based Study of the Bidirectional Association Between Obstructive Sleep Apnea and Type 2 Diabetes in Three Prospective U.S. Cohorts

The cumulative impact of type 2 diabetes and obstructive sleep apnoea on cardiovascular, liver, diabetes-related and cancer outcomes

AIM

A bidirectional relationship exists between obstructive sleep apnoea (OSA) and type 2 diabetes (T2D). We aimed to examine the cumulative impact of having both OSA and T2D on patient outcomes, relative to having either condition alone.

MATERIALS AND METHODS

Using TriNetX, a global federated research network (n = 128 million), we undertook two retrospective cohort studies, using time-to-event analysis. Analysis 1 compared OSA with T2D versus OSA alone; analysis 2 compared T2D with OSA versus T2D alone. Propensity score matching using greedy nearest neighbour (calliper 0.1) balanced the cohorts (1:1) for significant covariates. Primary outcomes were cardiovascular, liver, diabetes-related (microvascular) and cancer events over 1-5 years.

RESULTS

Analysis 1 (n = 179 688): A codiagnosis of T2D/OSA significantly increased risk of all-cause mortality (hazard ratio [HR] 1.52; confidence interval [CI]: 1.48, 1.57), dementia (HR 1.19; CI: 1.12, 1.26), liver (HR 2.20; CI: 1.77, 2.73), pancreatic (HR 1.62; CI: 1.35, 1.93), colon, renal and endometrial cancers; all cardiovascular, microvascular and liver related outcomes versus OSA alone over 1-5 5 years following OSA diagnosis. Analysis 2 (n = 240 094): A codiagnosis of OSA/T2D significantly increased the risk of peripheral (HR 1.39; CI: 1.36, 1.43) and autonomic (HR 1.63; CI: 1.51, 1.75) neuropathy; retinopathy (HR 1.13; CI: 1.09, 1.18), CKD (HR 1.21; CI: 1.18, 1.23); all cardiovascular and liver outcomes; all-cause mortality and several obesity related cancers versus T2D alone.

CONCLUSIONS

T2D significantly potentiates risk of cardiovascular, malignancy and liver-related outcomes in individuals with OSA. OSA, in individuals with T2D, significantly potentiates risk of cardiovascular disease, malignancy, death and several microvascular complications (retinopathy, CKD, peripheral/autonomic neuropathy).

Bidirectional interplay of sleep apnea syndrome and cardio-vascular disorders in diabetes

Although often overlooked sleep apnea has emerged as a significant public health concern. Obstructive sleep apnea (OSA) and diabetes commonly co-exist with a vicious cycle worsening the incidence and severity of both conditions. OSA has many implications including cardiometabolic disorders and impaired cardiovascular (CV) prognosis. OSA combined with diabetes generates a cumulative effect on CV outcomes. The association of OSA with several comorbidities including CV disease and heart failure is bi-directional meaning that some of them are likely to contribute to OSA. In patients with diabetes, OSA treatment should be integrated in a holistic strategy of prevention of CV and microvascular complications. This article provides some clues to advance the understanding of the interplay between OSA and CV disorders in diabetes and to consider the role of some CV risk markers like cardiac autonomic neuropathy and artery stiffness and of novel metrics for hypoxic-related events in CV risk stratification, and offers a discussion on the effects of medical approaches including weight loss strategies, GLP1-receptor agonists and sodium-glucose cotransporter 2 inhibitors. It provides a guidance to improve screening and diagnosis of OSA, and adherence to OSA treatment in patients with diabetes.

The knowledge profile, attitudes, and perioperative management of Chinese anesthesiologists towards patients with obstructive sleep apnea: a cross-sectional survey

BACKGROUNDS

Obstructive sleep apnea syndrome (OSA) is increasingly encountered by anesthesiologists in clinical practice. However, research on managing these patients among anesthesiologists in China is scarce. This study aims to investigate the knowledge, attitudes, and perioperative management strategies for OSA patients among Chinese anesthesiologists.

METHODS

In this cross-sectional study, anesthesiologists from various hospitals across China were invited to complete a thirty-eight-item online questionnaire survey between October 1 and November 1, 2022. The Obstructive Sleep Apnea Knowledge and Attitude (OSAKA) scale was utilized to measure their knowledge and attitudes.

RESULTS

A total of 470 valid participants were recruited for this research, resulting in a valid response rate of 73.3%. (1) While the majority of participants acknowledged the importance of identifying OSA during perioperative management, only 58.3% felt confident in managing OSA patients; (2) Anesthesiologists with higher professional titles and longer work experience exhibited greater confidence in managing OSA patients; (3) Just under half of the participants were familiar with the STOP-Bang and Berlin questionnaires. Anesthesiologists with over 20 years of work experience were more likely to use the STOP-Bang and Berlin questionnaires compared to those with less than 10 years of work experience (OR = 3.166, P < 0.001); (4) 71.1% of participants expressed approval regarding the preparation of sugammadex for muscle relaxation reversal, while only 32.8% approved the safety of opioid use for postoperative analgesia in OSA patients.

CONCLUSION

The study displayed that Chinese anesthesiologists have inadequate knowledge and perioperative management of OSA than expected. However, they have positive attitudes towards the assessment and management of OSA. The study highlights the need for high-quality training to identify and manage OSA among Chinese anesthesiologists.

Associations between obstructive sleep apnea and sleep characteristics with chronic kidney disease in rural Pennsylvania

STUDY OBJECTIVES

To examine the association between moderate-severe obstructive sleep apnea (msOSA) and sleep characteristics with chronic kidney disease (CKD) in a population of rural and urban adults in Pennsylvania.

METHODS

A cross-sectional study of 23,643 adults who underwent polysomnography (PSG) at a rural healthcare system in Pennsylvania between 2009 and 2019. Serum creatinine was abstracted from electronic health records to calculate estimated glomerular filtration rate (eGFR). CKD was defined as an eGFR <60 mL/min/1.73 m2. msOSA was defined as an apnea-hypoxia index (AHI) ≥15 events/hour. Poisson regression was performed to estimate the prevalence ratio (PR) of CKD for various sleep measures while adjusting for age, sex, race, smoking (never, former, current), body mass index, diabetes, and hypertension at time of PSG.

RESULTS

In this clinically-referred sample comprised of over one-third (35 %) rural individuals, the prevalence of CKD and msOSA was 9.4 % and 32.1 %, respectively. Patients with CKD had more severe OSA based on AHI and intermittent hypoxia profile and presented worse sleep quality across all studied measures. Having OSA was associated with a 13 % higher prevalence of CKD (95%CI: 1.04, 1.22). In addition, for every 5 % increment in sleep efficiency, the prevalence of CKD was 3 % lower (PR = 0.97, 95%CI: 0.96, 0.98). Significant associations that were in the expected direction were observed across most sleep characteristics in adjusted models.

CONCLUSIONS

Moderate-severe OSA, nocturnal hypoxemia, and disruptions to normal sleep duration, continuity, and architecture are associated with increased CKD prevalence in Pennsylvania adults. Management of OSA and/or sleep disturbances may be an opportunity to improve CKD outcomes. The unique health disparities among vulnerable rural populations are deserving of future study.

Sleep disorders in younger and middle-older age adults with newly diagnosed type 2 diabetes mellitus: A retrospective cohort study in >1million individuals

AIMS

To explore the 5-year incidence and relative rates of sleep disorders in younger (16-≤40 years) and middle-older (=>40 years) age adults with and without newly diagnosed type 2 diabetes.

METHODS

This retrospective, observational cohort study utilised data from the US Collaborative Network within the TriNetX database. We compared 5-year cumulative incidence of sleep disorders in younger (n = 110,088) and middle-older populations (n = 1,185,961).

RESULTS

The absolute risk of developing any type of sleep disorder was greater in individuals with type 2 diabetes vs. those without. Over the 5-year follow-up period, 14.2 % of younger adults and 18.5 % of middle-older age adults with newly diagnosed type 2 diabetes developed any form of sleep disorder, compared to 4.5 % and 7.9 % propensity matched individuals without diabetes. We observed a more pronounced relative rate across the observed sleep disorders in younger adults.

CONCLUSIONS

The 5-year risk of sleep disorders is higher in those with newly diagnosed type 2 diabetes vs. those without. A higher absolute risk was seen in middle-older adults, but relative rates were consistently higher in younger adults with type 2 diabetes. Sleep should be regularly discussed as part of a holistic approach to diabetes care, particularly in those aged ≤40.

Association of Obstructive Sleep Apnea on Heart Failure and Its Risk Factors: A Two-Step Mendelian Randomization Study

INTRODUCTION

Recent studies have indicated that obstructive sleep apnea (OSA) is linked to a higher likelihood of heart failure (HF). However, the causal connection between the two conditions is uncertain. We aimed to investigate the causal association of OSA with HF and its risk factors.

METHODS

The OSA summary statistics are derived from the FinnGen database, including 38,998 cases and 336,659 controls. HF summary statistics come from HERMES, the UK Biobank, and the FinnGen database. A two-sample mendelian randomization (MR) analysis was conducted to examine the causality of OSA on HF risk. Furthermore, the mediator effect of potential risk factors was assessed by a two-step MR.

RESULTS

The results of MR analysis demonstrated that genetically determined OSA is causal associated with the higher likelihood of HF (HERME: odds ratio [OR] = 1.222; 95% confidence interval [CI]: 1.091, 1.369; p = 5.19 × 10-4) (FinnGen: OR = 1.233; 95% CI: 1.129, 1.346; p = 3.32 × 10-6) (UK Biobank: OR = 1.002; 95% CI: 1.000, 1.003; p = 0.014). Two-step MR analysis indicated that obesity, blood glucose, depression, and other CVDs have significant mediating effects on the causal effect between OSA and HF.

CONCLUSION

This MR study emphasizes the causal effect of OSA on HF risk. Adiposity traits play a major role in the process of OSA leading to HF. Considering the detrimental impact of OSA on HF, it becomes imperative to prioritize the prevention and management of HF in individuals afflicted with OSA. The foremost intervention strategy should revolve around effective obesity management.

The Prevalence of Obstructive Sleep Apnea in Patients With Primary Aldosteronism

CONTEXT

Investigating the co-occurrence of obstructive sleep apnea (OSA) and primary aldosteronism (PA) is crucial for understanding their interrelation.

OBJECTIVE

This work aimed to evaluate the prevalence of OSA in individuals diagnosed with PA and to assess the prevalence of PA within the OSA population, with a specific focus on hypertensive individuals.

METHODS

An exhaustive search was performed across PubMed, Embase, CINAHL, Scopus, and Web of Science up to September 2023, without restrictions on language or publication date. Studies were selected based on their focus on the prevalence of OSA in PA patients and vice versa, specifically in hypertensive individuals. Data were extracted using standard guidelines, focusing on patient characteristics, prevalence rates, and other relevant clinical parameters.

RESULTS

Proportional meta-analysis using a random-effects model revealed a 59.8% prevalence of OSA in hypertensive PA patients, with 45.4% exhibiting moderate-to-severe OSA. Meta-regression showed no significant effect of age, sex, body mass index, antihypertensive medication, systolic blood pressure, diastolic blood pressure, or serum potassium on OSA prevalence. However, a significant positive association was found with the glomerular filtration rate (GFR) (P < .001). Subgroup analysis also revealed that a hyperfiltration rate (GFR ≥ 100 mL/min per 1.73 m2) may be associated with a higher prevalence of OSA (71%, P value for interaction < .01). Among hypertensive OSA patients, 11.2% had PA.

CONCLUSION

A substantial prevalence of OSA in individuals with PA was identified, demonstrating a complex interplay between these conditions in hypertensive patients. Notably, the prevalence of OSA was significantly associated with kidney hyperfiltration.

Obstructive sleep apnea mediates genetic risk of Diabetes Mellitus: The Hispanic Community Health Study/Study of Latinos

Objective

We sought to evaluate whether obstructive sleep apnea (OSA), and other sleep disorders, increase genetic risk of developing diabetes mellitus (DM).

Research Design and Methods

Using GWAS summary statistics from the DIAGRAM consortium and Million Veteran Program, we developed multi-ancestry Type 2 Diabetes (T2D) polygenic risk scores (T2D-PRSs) useful in admixed Hispanic/Latino individuals. We estimated the association of the T2D-PRS with cross-sectional and incident DM in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL). We conducted a mediation analysis with T2D-PRSs as an exposure, incident DM as an outcome, and OSA as a mediator. Additionally, we performed Mendelian randomization (MR) analysis to assess the causal relationship between T2D and OSA.

Results

Of 12,342 HCHS/SOL participants, at baseline, 48.4% were normoglycemic, 36.6% were hyperglycemic, and 15% had diabetes, and 50.9% identified as female. Mean age was 41.5, and mean BMI was 29.4. T2D-PRSs was strongly associated with baseline DM and with incident DM. At baseline, a 1 SD increase in the primary T2D-PRS had DM adjusted odds ratio (OR) = 2.67, 95% CI [2.40; 2.97] and a higher incident DM rate (incident rate ratio (IRR) = 2.02, 95% CI [1.75; 2.33]). In a stratified analysis based on OSA severity categories the associations were stronger in individuals with mild OSA compared to those with moderate to severe OSA. Mediation analysis suggested that OSA mediates the T2D-PRS association with DM. In two-sample MR analysis, T2D-PRS had a causal effect on OSA, OR = 1.03, 95% CI [1.01; 1.05], and OSA had a causal effect on T2D, with OR = 2.34, 95% CI [1.59; 3.44].

Conclusions

OSA likely mediates genetic effects on T2D.

A systematic review of the methodology for examining the relationship between obstructive sleep apnea and type two diabetes mellitus

Background

The association between obstructive sleep apnea (OSA) and type 2 diabetes mellitus (T2DM) has been explored in various studies, revealing inconsistent correlations that impact therapeutic effectiveness. This heterogeneity in findings requires further exploration to understand what may be driving this. Therefore, this study focuses on systematically reviewing the data, classification of variables, and analytical approach to understand if and how this may be contributing to the mixed findings. This review aims to provide insights that can enhance the generalisability of future research findings.

Methods

A comprehensive electronic search was conducted, including EMBASE, MEDLINE, PsycINFO, CINAHL, Web of Science Core Collection, Scopus and specialised sleep journals. The included studies were observational studies published in English from 2011 onwards, involving adults above 18 years with OSA and T2DM or prediabetes, and included a control group. Exclusions were pregnant women, interventional studies, randomised trials, systematic reviews, conference abstracts, case studies and studies without a control group or only with descriptive analysis.

Results

We reviewed 23 studies that met the inclusion criteria. Among cohort studies, 54% did not report attrition rates, and 52% did not detail methods for handling missing data in all studies. Nine studies (39%) predominantly included male participants. Objective measures were prevalent in assessing OSA, with 11 using home portable sleep monitors and four employing clinic polysomnography, though only three validated home sleep monitors. The apnea-hypopnea index was commonly used to define OSA severity, with six studies adapting the American Academy of Sleep Medicine criteria. Two studies utilised validated self-report questionnaires for OSA symptoms. T2DM diagnosis methods varied, with 17 studies using blood samples, two relying only on self-reporting, and four confirmed diagnosis via medical records.

Conclusions

The variability in sample characteristics, data quality, and variable coding may contribute to the mixed finding. This review identifies gaps in using the standardised measures, reporting attrition rates, handling missing data, and including both sexes. Addressing these issues is crucial to enhancing future research generalisability. Standardising diagnostic criteria, considering clinical and sociodemographic factors, and ensuring inclusivity in study populations are essential for advancing understanding and treatment strategies for OSA and T2DM.

Protocol registration

https://www.crd.york.ac.uk/prospero, identifier CRD42023397547.

Association between alcohol use disorder and risk of obstructive sleep apnea

Obstructive sleep apnea (OSA) is a common sleep disorder characterised by recurrent upper airway collapse during sleep. Alcohol consumption has been linked to an increased risk of OSA due to its effects on the upper airway and body mass index (BMI). We aimed to investigate the correlation between alcohol use disorders and OSA. We used 11,859 participants data from Korean National Health and Nutrition Examination Surveys. The variable of interest was alcohol use disorder, measured using the Alcohol Use Disorders Identification Test, and the dependent variable was the risk of OSA, measured using the Snoring, Tiredness, Observed apnea, high blood Pressure, BMI, age, neck circumference, and male gender questionnaires. Multiple logistic regression was used to assess the association between alcohol use disorder and OSA risk after adjusted analysis. A significant association was found between alcohol use disorder and OSA (adjusted odds ratio [aOR] 2.14, 95% confidence interval [CI] 1.93-2.37). In the unemployed group, those with alcohol use disorder had the highest odds of being at risk of OSA compared with those who did not have this disorder (aOR 2.45, 95% CI 2.04-2.95). The OSA risk increased as the snoring frequency, amount of alcohol consumed, and frequency of binge drinking increased. This study suggests an association between alcohol use disorders and the risk of OSA. The frequency of alcohol consumption, quantity of alcohol consumed, and snoring frequency were associated with the risk of OSA. Therefore, ceasing alcohol consumption is recommended as an effective approach to enhancing sleep quality.

Prevalence of obstructive sleep apnea in whole spectrum chronic kidney disease patients: A systematic review and meta-analysis

BACKGROUND

Obstructive sleep apnea (OSA) is a common sleep disorder among chronic kidney disease (CKD) patients, associated with considerable morbidity. Various studies from around the globe have reported different prevalence rates.

OBJECTIVE

This systematic review and meta-analysis aimed to determine the prevalence of OSA and quantify the relationship between OSA and mortality risk in patients with CKD.

METHODS

Four databases were systematically searched, and additional references to relevant articles were manually searched. The prevalence of OSA and the mortality risk based on random-effects models were assessed using percentages and hazard ratio (HR) with a 95 % confidence interval (95 % CI). In addition, the heterogeneity between studies was assessed using I2 statistics.

RESULTS

A total of 44 literature (47 studies with 223,967 participants) met the eligibility criteria for the meta-analysis. The results showed that the prevalence of OSA in CKD patients was reported to be 39.3 % (95 % CI, 32.3-46.7). Among study participants in different age groups, the highest prevalence of OSA was found in CKD respondents aged 60 years or older, at 47.1 % (95 % CI 34.4-60.3). Of the eight literature (10 cohorts) that provided survival data, the pooled estimates indicated a 26.5 % (HR: 1.265; 95 % CI 1.021-1.568) higher mortality risk in subjects with OSA than CKD patients without OSA.

CONCLUSIONS

This systematic review and meta-analysis found that more than 1/3 of CKD patients have comorbid OSA, which increases the risk of early death in CKD patients. These results should help policymakers to provide adequate healthcare for this population.

PROSPERO REGISTRATION ID

CRD42023465497.

Association of comorbid obstructive sleep apnea and insomnia with risk of major adverse cardiovascular events in sleep medicine center patients

OBJECTIVES

To investigate the association between comorbid obstructive sleep apnea and insomnia and major adverse cardiovascular events, including myocardial infarction, unstable angina, congestive heart failure, and stroke, in adults with suspected sleep disorders who underwent sleep apnea testing.

METHODS

We conducted a retrospective analysis of electronic medical records data from patients with clinical encounters at sleep medicine centers to identify patients with comorbid obstructive sleep apnea and insomnia, obstructive sleep apnea only, insomnia only, and patients without a diagnosis of obstructive sleep apnea or insomnia (i.e., controls). Obstructive sleep apnea, insomnia, comorbidities, and new-onset major adverse cardiovascular events were ascertained by ICD-9-CM and ICD-10-CM codes. Multivariable adjusted Cox proportional regression models evaluated the risk of major adverse cardiovascular events over a 10-year follow-up period.

RESULTS

A total of 3951 patients, 226 controls, 2107 with obstructive sleep apnea only, 276 with insomnia only, and 1342 with comorbid obstructive sleep apnea and insomnia, were included in the analysis. Compared to controls, comorbid obstructive sleep apnea and insomnia were associated with a significantly higher risk of developing major adverse cardiovascular events (hazard ratio 3.60, 95 CI%: 2.33-5.91) in unadjusted analyses. The relationship between comorbid obstructive sleep apnea and insomnia and major adverse cardiovascular events remained after adjustment for demographic and behavioral factors, but not after further adjustment for comorbidities. The greatest risk of major adverse cardiovascular events was found among younger adults with comorbid obstructive sleep apnea and insomnia. Obstructive sleep apnea only was associated with greater risk of major adverse cardiovascular events in unadjusted analyses only (hazard ratio 2.77, 95% CI: 1.80-4.54). Insomnia only was not significantly associated with increased risk of major adverse cardiovascular events.

CONCLUSIONS

Comorbid obstructive sleep apnea and insomnia may be a high-risk group for major adverse cardiovascular events, particularly younger adults. Further research is needed to better understand the association between comorbid obstructive sleep apnea and insomnia and major adverse cardiovascular events risk.

Sleep apnea, the risk of out-of-hospital cardiac arrest, and potential benefits of continuous positive airway pressure therapy: A nationwide study

OBJECTIVE

Patients with sleep apnea (SA) are at increased cardiovascular risk. However, little is known about the risk of out-of-hospital cardiac arrest (OHCA) in patients with SA. Therefore, we studied the relation between SA patients who did and did not receive continuous positive airway pressure (CPAP) therapy with OHCA in the general population.

METHODS

Using nationwide databases, we conducted a nested case-control study with OHCA-cases of presumed cardiac causes and age/sex/OHCA-date matched non-OHCA-controls from the general population. Conditional logistic regression models with adjustments for well-known OHCA risk factors were performed to generate odds ratio (OR) of OHCA comparing patients with SA receiving and not receiving CPAP therapy with individuals without SA.

RESULTS

We identified 46,578 OHCA-cases and 232,890 matched non-OHCA-controls [mean: 71 years, 68.8% men]. Compared to subjects without SA, having SA without CPAP therapy was associated with increased odds of OHCA after controlling for relevant confounders (OR:1.20, 95%-Cl:1.06-1.36), while having SA with CPAP therapy was not associated with OHCA (OR:1.04, 95%-Cl:0.93-1.36). Regardless of CPAP therapy, age and sex did not significantly influence our findings. Our findings were confirmed in: (I) patients with neither ischemic heart disease nor heart failure (untreated SA, OR:1.24, 95%-CI:1.04-1.47; SA with CPAP, OR:1.08, 95%-CI:0.93-1.25); and (II) in patients without cardiovascular disease (untreated SA, OR:1.33, 95%-CI:1.07-1.65; SA with CPAP, OR:1.14, 95%-CI:0.94-1.39).

CONCLUSION

SA not treated with CPAP was associated with OHCA, while no increased risk of OHCA was found for SA patients treated with CPAP.

Genome-wide association analysis of composite sleep health scores in 413,904 individuals

Recent genome-wide association studies (GWASs) of several individual sleep traits have identified hundreds of genetic loci, suggesting diverse mechanisms. Moreover, sleep traits are moderately correlated, and together may provide a more complete picture of sleep health, while also illuminating distinct domains. Here we construct novel sleep health scores (SHSs) incorporating five core self-report measures: sleep duration, insomnia symptoms, chronotype, snoring, and daytime sleepiness, using additive (SHS-ADD) and five principal components-based (SHS-PCs) approaches. GWASs of these six SHSs identify 28 significant novel loci adjusting for multiple testing on six traits (p<8.3e-9), along with 341 previously reported loci (p<5e-08). The heritability of the first three SHS-PCs equals or exceeds that of SHS-ADD (SNP-h2=0.094), while revealing sleep-domain-specific genetic discoveries. Significant loci enrich in multiple brain tissues and in metabolic and neuronal pathways. Post GWAS analyses uncover novel genetic mechanisms underlying sleep health and reveal connections to behavioral, psychological, and cardiometabolic traits.

Clinical efficacy and metabolomics study of Wendan Decoction in the treatment of phlegm-dampness obstructive sleep apnea-hypopnea syndrome with type 2 diabetes mellitus

ETHNOPHARMACOLOGICAL RELEVANCE

Wendan Decoction (WDD) is one of the classic traditional Chinese prescriptions that has been used in the treatment of type 2 diabetes mellitus (T2DM), metabolic syndrome, obstructive sleep apnea-hypopnea syndrome (OSAHS) and so on. The therapeutic effects and mechanism of WDD remain to be explored, especially from the perspective of metabolomics, oxidative stress and inflammation.

AIM OF THE STUDY

To investigate the therapeutic and metabolic regulatory effects and the underlying mechanism of WDD in OSAHS with T2DM patients.

MATERIALS AND METHODS

All included patients were from Rudong Hospital of Traditional Chinese Medicine, Nantong, Jiangsu Province, China. Both groups received lifestyle interventions; at the same time, all of them were administered metformin (1500 mg/day) and dapagliflozin (10 mg/day), and the treatment group was administered WDD orally. All patients were treated for two months. Before and after treatment, the changes in clinical symptoms and signs of the two groups of patients were evaluated, and the detection indicators such as body mass index (BMI), apnea-hypopnea index (AHI), lowest arterial oxygen saturation (LSaO2), Epworth sleepiness scale (ESS), percentage of total sleep time with oxygen saturation <90% (TST90), fasting plasma glucose (FPG), 2-h post-load glucose(2h-PG), fasting insulin (FINS), homeostasis model assessment of insulin resistance (HOMA-IR)，hemoglobin A1c (HbA1c), blood lipid levels, as well as the adverse reactions and compliance of the patients were observed and detection of serum metabolites in patients to screen out specific biomarkers. The serum metabolic profile of WDD in OSAHS with T2DM patients was explored using ultra-high-performance liquid chromatography-quadrupole/electrostatic field orbitrap high-resolution mass spectrometry (UPLC-Q Orbitrap HRMS).

RESULTS

After treatment with WDD for 8 weeks, biochemical indicators, including BMI, FPG, 2h-PG, blood lipid, FINS, HbA1c, AHI, ESS, LSaO2, TST90, and HOMA-IR, were significantly improved. Serum metabolomic analysis showed that metabolites were differentially expressed before and after WDD-treated patients. Metabolomics results revealed that WDD regulated the biomarkers, such as DL-arginine, guaiacol sulfate, azelaic acid, phloroglucinol, uracil, L-tyrosine, cascarillin, Cortisol and L-alpha-lysophosphatidylcholine. Pathway enrichment analysis showed that the metabolites were associated with oxidative stress and inflammation.

CONCLUSION

The study based on clinical research and metabolomics indicated that WDD can improve OSAHS with T2DM through multiple targets and pathways, and it may be a useful alternative therapy for the treatment of OSAHS with T2DM patients.

Severity of sleep apnea impairs adipose tissue insulin sensitivity in individuals with obesity and newly diagnosed obstructive sleep apnea

Introduction

Obstructive sleep apnea (OSA) is a common sleep disorder associated with increased risk for the development of type 2 diabetes. While studies have examined the effects of sleep on whole-body insulin sensitivity, little is known about the effects of sleep on adipose tissue insulin sensitivity in patients with OSA. We analyzed if the severity of OSA, measured by apnea-hypopnea index (AHI), is associated with adipose tissue insulin sensitivity.

Methods

We examined the relationship between sleep parameters and adipose tissue insulin sensitivity in non-diabetic participants with obesity and newly diagnosed OSA who underwent overnight polysomnography and a 2 h oral glucose tolerance test during which circulating free fatty acids were measured. In total, 16 non-diabetic participants with obesity and newly diagnosed OSA (sex, 81.3% males; mean age, 50.9 ± 6.7 y; BMI, 36.5 ± 2.9 kg/m2; AHI, 43 ± 20 events/h) were included in the analysis.

Results

In our study participants, AHI is inversely associated with free-fatty acid suppression during oral glucose challenge (R = -0.764, p = 0.001). This relationship persisted even after statistical adjustment for age (R = -0.769, p = 0.001), body mass index (R = -0.733, p = 0.002), waist-to-hip ratio (R = -0.741, p = 0.004), or percent body fat mass (R = -0.0529, p = 0.041). Furthermore, whole-body insulin sensitivity as determined by the Matsuda index was associated with percent REM sleep (R = 0.552, p = 0.027) but not AHI (R = -0.119, p = 0.660).

Conclusion

In non-diabetic patients with OSA, the severity of sleep apnea is associated with adipose tissue insulin sensitivity but not whole-body insulin sensitivity. The impairments in adipose tissue insulin sensitivity may contribute to the development of type 2 diabetes.

Efficacy and safety of liraglutide in patients with type 2 diabetes mellitus and severe obstructive sleep apnea

OBJECTIVES

To observe the efficacy and side effects of liraglutide in the treatment of type 2 diabetes mellitus (T2DM) patients with severe obstructive sleep apnea (OSA).

METHODS

The study conducted in an outpatient setting was a two-center, prospective randomized controlled study. T2DM patients with severe OSA were randomized to the control group (continuous positive airway pressure [CPAP] and drug treatment without liraglutide) or the liraglutide group (CPAP and drug treatment including liraglutide). Demographic and clinical characteristics, sleep-disordered breathing indices, cardiac function indices, and side effects were evaluated and compared between the two groups before and after 3 months.

RESULTS

Of 90 patients, 45 were randomized to the intervention arm (with liraglutide) and 45 to the control arm (without liraglutide). One patient in the liraglutide group dropped out of the study on day 8 after enrollment due to obvious gastrointestinal symptoms. No significant differences were found between the two groups in baseline demographics, clinical characteristics, cardiac function indicators, or sleep disorder respiratory indices (P > 0.05). After 3 months, the body mass index (BMI), apnea hypopnea index (AHI), and mean systolic blood pressure in the liraglutide treatment group were significantly lower than those in the control group (P < 0.05). The minimum oxygen saturation was significantly higher in the liraglutide group compared with that in the control group after 3 months of follow-up (P < 0.05). No difference was found between the two groups in the summary of side effects (P > 0.05).

CONCLUSIONS

Liraglutide combined with CPAP can effectively reduce BMI, lower mean systolic blood pressure, and improve AHI scores and hypoxia in T2DM patients with severe OSA. Liraglutide did not increase side effects.

Molecular Processes Involved in the Shared Pathways between Cardiovascular Diseases and Diabetes

Cardiovascular diseases and diabetes mellitus are currently among the diseases with the highest morbidity and mortality. The pathogenesis and development of these diseases remain strongly connected, along with inflammation playing a major role. Therefore, the treatment possibilities showing a positive impact on both of these diseases could be especially beneficial for patients. SGLT-2 inhibitors and GLP-1 receptor agonists present this dual effect. Moreover, the hostile composition of the gut microbiota could influence the progression of these conditions. In this review, the authors present the latest knowledge on and innovations in diabetes mellitus and CVD-with the focus on the molecular mechanisms and the role of the microbiota.

Disparities in Sleep-Disordered Breathing: Upstream Risk Factors, Mechanisms, and Implications

Sleep-disordered breathing (SDB) refers to a spectrum of disorders ranging from habitual snoring without frank episodes of obstructed breathing or desaturation during sleep to obstructive sleep apnea, where apneas and hypopneas repetitively occur with resultant intermittent hypoxia, arousal, and sleep disruption. Disparities in SDB reflect its overall high prevalence in children and adults from racially and ethnically minoritized or low socioeconomic status backgrounds coupled with high rates of underdiagnosis and suboptimal treatment.

Cardiovascular Disease Outcomes Associated with Obstructive Sleep Apnea in Diabetics: A Systematic Review and Meta-Analysis

BACKGROUND

There is significant pathogenic and epidemiological overlap between diabetes and obstructive sleep apnea (OSA). This systematic review aimed to ascertain the association between OSA and cardiovascular disease (CVD) in a diabetic population.

METHODS

The study protocol was registered with PROSPERO (CRD42023404126). On 15 July 2023, a comprehensive search of the literature was performed in PubMed, EBSCO, Scopus, ProQuest, and Web of Science, using keywords and synonyms of OSA, diabetes, and CVD, coupled with specific terms for different CVDs. Only observational studies that reported CVD events in diabetics (with and without OSA) were included. The quality of the studies included in the analysis was assessed using the Newcastle-Ottawa Scale.

RESULTS

In the primary literature search, 8795 studies were identified, of which 9 met the inclusion criteria and included 17,796 participants. Eight studies were eligible for meta-analysis, and a pooled risk ratio (RR) of 1.29 (95% CI = 0.91-1.83) was found for developing CVD in diabetics with OSA at a 95% prediction interval of 0.30-5.60. The included studies showed significant heterogeneity with an I2 value of 91%.

CONCLUSION

These findings show the possible association between OSA and diabetes and their impact on CVDs. Identifying and managing OSA in individuals with diabetes at an early phase could potentially reduce the risk of CVDs and its related complications.

Obstructive sleep apnoea heterogeneity and cardiovascular disease

Obstructive sleep apnoea (OSA), characterized by recurrent periods of upper airway obstruction and intermittent hypoxaemia, is prevalent in patients with cardiovascular disease (CVD), and is therefore important to consider in the prevention and management of CVD. Observational studies indicate that OSA is a risk factor for incident hypertension, poorly controlled blood pressure, stroke, myocardial infarction, heart failure, cardiac arrhythmias, sudden cardiac death and all-cause death. However, clinical trials have not provided consistent evidence that treatment with continuous positive airway pressure (CPAP) improves cardiovascular outcomes. These overall null findings might be explained by limitations in trial design and low levels of adherence to CPAP. Studies have also been limited by the failure to consider OSA as a heterogeneous disorder that consists of multiple subtypes resulting from variable contributions from anatomical, physiological, inflammatory and obesity-related risk factors, and resulting in different physiological disturbances. Novel markers of sleep apnoea-associated hypoxic burden and cardiac autonomic response have emerged as predictors of OSA-related susceptibility to adverse health outcomes and treatment response. In this Review, we summarize our understanding of the shared risk factors and causal links between OSA and CVD and emerging knowledge on the heterogeneity of OSA. We discuss the varied mechanistic pathways that result in CVD that also vary across subgroups of OSA, as well as the potential role of new biomarkers for CVD risk stratification.

Effect of obstructive sleep apnea on prognosis in patients with acute coronary syndromes with varying numbers of standard modifiable risk factors: insight from the OSA-ACS study

BACKGROUND

Standard modifiable risk factors (SMuRFs) increase the risk of cardiovascular events in patients with acute coronary syndrome (ACS) and are also strongly associated with obstructive sleep apnea (OSA) in a bidirectional relationship. However, the association of OSA with recurrent cardiovascular events in ACS patients based on the number of SMuRFs remains unclear. Hence, we aimed to elucidate the prognostic implication of OSA in ACS patients stratified by the number of SMuRFs.

METHODS

This was a post hoc analysis of the OSA-ACS study (NCT03362385), including 1927 patients admitted for ACS and undergoing portable sleep monitoring. OSA was defined as an apnea hypopnea index ≥ 15 events/h. The primary endpoint was major adverse cardiovascular and cerebrovascular event (MACCE) including cardiovascular death, myocardial infarction, stroke, hospitalization for unstable angina or heart failure, and ischemia-driven revascularization. Cox proportional hazards model and Kaplan-Meier analysis were used to investigated the relationship between OSA and subsequent cardiovascular events after patients were stratified by the number of SMuRFs.

RESULTS

Among 1927 patients enrolled, 130 (6.7%) had no SMuRF, 1264 (65.6%) exhibited 1-2 SMuRFs and 533 (27.7%) presented 3-4 SMuRFs. With the increase of the number of SMuRFs, the proportion of OSA in ACS patients tended to increase (47.7% vs. 51.5% vs. 56.6%), but there was no significant difference between them (P = 0.08). After the stratification of ACS patients via SMuRF numbers and adjustment for confounding factors, fully adjusted Cox regression indicated that OSA increased the risk of MACCE (adjusted HR, 1.65; 95%CI, 1.06-2.57; P = 0.026) and ischemia-driven revascularization (adjusted HR, 2.18; 95%CI, 1.03-4.65; P = 0.042) in ACS patients with 3-4 SMuRFs.

CONCLUSIONS

In hospitalized ACS patients, OSA is associated with an increased risk of MACCE and ischemia-driven revascularization among patients with 3-4 SMuRFs. Therefore, screening for OSA should be emphasized in ACS patients with 3-4 SMuRFs, and intervention trials should be prioritized in these high-risk patients.

Prevalence of sleep-related breathing disorders and associated risk factors among people with dementia: A meta-analysis

OBJECTIVE

Sleep-related breathing disorders (SRBD) have shown to cause worsened cognitive impairment among people with dementia. Therefore, we conducted the first meta-analysis to estimate the prevalence of SRBD among people with dementia.

METHODS

Comprehensive searches were conducted in Embase, Ovid-MEDLINE, PubMed, PsycINFO, Scopus, Web of Science, and CINAHL. The generalized linear mixed model (GLMM) was used for the pooled prevalence analysis and heterogeneity using I² test and Cochran's Q-statistic in R-software. Study quality was assessed by Hoy's risk of bias assessment tool. Overall, 20 studies from 1282 studies were included with 1461 participants.

RESULTS

The pooled prevalence of SRBD among dementia was 59% (95%CI: 44%-73%) with 55% (95%CI: 34%-74%) for obstructive sleep apnea (OSA), 49% (95%CI: 25%-73%) for unspecified SRBD, and 11% (95%CI: 5%-21%) for central sleep apnea (CSA). Regarding dementia subtypes, the prevalence of SRBD was 89% (95%CI: 61%-97%) for Alzheimer's dementia, 56% (95%CI: 48%-63%) for Parkinson's and Idiopathic Parkinson's dementia, and 16% (95%CI: 8%-30%) for Huntington's dementia. Significant moderator variables were male, body mass index, larger waist and hip circumference, waist-hip ratio, and comorbidities including hypertension, dyslipidemia, renal disease, diabetes, heart disease, and stroke.

CONCLUSIONS

There is considerable high prevalence of SRBD among dementia people, with OSA and unspecified SRBD being fivefold higher than CSA. Regarding dementia subtypes, Parkinson's and Idiopathic Parkinson's, and Alzheimer's dementia had four to sixfold increased risk of presenting with SRBD than Huntington's dementia. Therefore, assessment and management of SRBD in Alzheimer's, and Parkinson's and Idiopathic Parkinson's dementia deserves more attention in future research.

Multimorbidity and Sleep Patterns among Adults in a Peruvian Semi-Urban Area

Objective  To assess if the duration and quality of sleep vary due to the presence of multimorbidity. Materials and Methods  We performed a secondary analysis using data from a population-based study involving adult subjects aged between 30 and 69 years residing in a semi-urban area of Tumbes, Peru. The duration (normal, short or prolonged) and quality (good or poor) of sleep were our outcome variables, whereas the exposure was multimorbidity (two or more chronic conditions). Crude and adjusted Poisson regression models were built to assess the association of interest, and prevalence ratios (PRs) and 95% confidence intervals (95%CIs) were reported. Results  We analyzed data from 1,607 subjects with a mean age of 48.2 (standard deviation [SD]: ± 10.6) years, 809 (50.3%) of whom were women. Multimorbidity was present in 634 (39.5%; 95%CI: 37.1-41.9%) subjects, and 193 (12.1%; 95%CI: 10.5-13.7%) were short sleepers, 131 (8.2%; 95%CI: 6.9-9.6%) were long sleepers, and 312 (19.5%; 95%CI: 17.5-21.5%) had poor sleep quality. In the multivariable model, multimorbidity was associated with prolonged sleep duration (PR = 1.45; 95%CI: 1.03-2.04) and poor sleep quality (PR = 2.04; 95%CI: 1.65-2.52). Conclusions  Multimorbidity was associated with prolonged, but not short, sleep duration, as well as with poor sleep quality. Our results suggest the need of assessing sleep patterns among adults with multimorbidity.

Persistent obstructive sleep apnoea in children: treatment options and management considerations

Unresolved obstructive sleep apnoea (OSA) after an adenotonsillectomy, henceforth referred to as persistent OSA, is increasingly recognised in children (2-18 years). Although associated with obesity, underlying medical complexity, and craniofacial disorders, persistent OSA also occurs in otherwise healthy children. Inadequate treatment of persistent OSA can lead to long-term adverse health outcomes beyond childhood. Positive airway pressure, used as a one-size-fits-all primary management strategy for persistent childhood OSA, is highly efficacious but has unacceptably low adherence rates. A pressing need exists for a broader, more effective management approach for persistent OSA in children. In this Personal View, we discuss the use and the need for evaluation of current and novel therapeutics, the role of shared decision-making models that consider patient preferences, and the importance of considering the social determinants of health in research and clinical practice. A multipronged, comprehensive approach to persistent OSA might achieve better clinical outcomes in childhood and promote health equity for all children.

Relationship between obstructive sleep apnea, insulin resistance, and metabolic syndrome: a nationwide population-based survey

We aimed to identify the association between obstructive sleep apnea (OSA), insulin resistance (IR), and metabolic syndrome (MetS) in a nationwide population-based sample. A total of 7,900 adults with information on the STOP-Bang score and MetS (3,341 men and 4,469 women) were identified from the dataset of the Korea National Health and Nutrition Examination Survey 2019-2020. The association between OSA, IR, MetS, and its components was estimated using complex sample logistic regression analysis with adjustments for age, body mass index, residence, smoking status, alcohol consumption, household income, education, and the presence of diabetes. Participants with a high OSA score were more likely to have IR (odds ratio [OR] 2.78, 95% confidence interval [CI] 1.96-3.95 in men and OR 2.64, 95% CI 0.55-12.80 in women), MetS (OR 6.05, 95% CI 4.23-8.69 in men and OR 4.20, 95% CI 1.23-15.70 in women), and components of MetS, compared to individuals with a low OSA score. Compared to premenopausal women, postmenopausal women had a more intense association between OSA and IR (OR 1.78, 95% CI 0.13-24.43 for premenopausal women and OR 3.64, 95% CI 0.60-22.28 for postmenopausal women) and MetS (OR 2.58, 95% CI 0.23-29.55 for premenopausal women and OR 5.36, 95% CI 1.42-20.21 for postmenopausal women). OSA was associated with abdominal obesity and hypertension in premenopausal women, while all components of MetS were associated with OSA in postmenopausal women. Further studies are necessary to elucidate the underlying mechanisms of these findings.

The Influence of Comorbidities on Chemokine and Cytokine Profile in Obstructive Sleep Apnea Patients: Preliminary Results

INTRODUCTION

Obstructive sleep apnea (OSA) is frequently associated with a chronic inflammatory state and cardiovascular/metabolic complications. The aim of this study was to evaluate the influence of certain comorbidities on a panel of 45 chemokines and cytokines in OSA patients with special regard to their possible association with cardiovascular diseases.

MATERIAL AND METHODS

This cross-sectional study was performed on 61 newly diagnosed OSA patients. For the measurement of the plasma concentration of chemokines and cytokines, the magnetic bead-based multiplex assay for the Luminex^® platform was used.

RESULTS

In the patients with concomitant COPD, there were increased levels of pro-inflammatory cytokines (CCL11, CD-40 ligand) and decreased anti-inflammatory cytokine (IL-10), while in diabetes, there were increased levels of pro-inflammatory cytokines (IL-6, TRIAL). Obesity was associated with increased levels of both pro-inflammatory (IL-13) and anti-inflammatory (IL-1RA) cytokines. Hypertension was associated with increased levels of both pro-inflammatory (CCL3) and anti-inflammatory (IL-10) cytokines. Increased daytime pCO₂, low mean nocturnal SaO₂, and the oxygen desaturation index were associated with increased levels of pro-inflammatory cytokines (CXCL1, PDGF-AB, TNF-α, and IL-15).

CONCLUSIONS

In OSA patients with concomitant diabetes and COPD, elevated levels of certain pro-inflammatory and decreased levels of certain anti-inflammatory cytokines may favor the persistence of a chronic inflammatory state with further consequences. Nocturnal hypoxemia, frequent episodes of desaturation, and increased daytime pCO₂ are factors contributing to the chronic inflammatory state in OSA patients.

Sleep duration, plasma metabolites, and obesity and diabetes: a metabolome-wide association study in US women

Short and long sleep duration are associated with adverse metabolic outcomes, such as obesity and diabetes. We evaluated cross-sectional differences in metabolite levels between women with self-reported habitual short (<7 h), medium (7-8 h), and long (≥9 h) sleep duration to delineate potential underlying biological mechanisms. In total, 210 metabolites were measured via liquid chromatography-mass spectrometry in 9207 women from the Nurses' Health Study (NHS; N = 5027), the NHSII (N = 2368), and the Women's Health Initiative (WHI; N = 2287). Twenty metabolites were consistently (i.e. praw < .05 in ≥2 cohorts) and/or strongly (pFDR < .05 in at least one cohort) associated with short sleep duration after multi-variable adjustment. Specifically, levels of two lysophosphatidylethanolamines, four lysophosphatidylcholines, hydroxyproline and phenylacetylglutamine were higher compared to medium sleep duration, while levels of one diacylglycerol and eleven triacylglycerols (TAGs; all with ≥3 double bonds) were lower. Moreover, enrichment analysis assessing associations of metabolites with short sleep based on biological categories demonstrated significantly increased acylcarnitine levels for short sleep. A metabolite score for short sleep duration based on 12 LASSO-regression selected metabolites was not significantly associated with prevalent and incident obesity and diabetes. Associations of single metabolites with long sleep duration were less robust. However, enrichment analysis demonstrated significant enrichment scores for four lipid classes, all of which (most markedly TAGs) were of opposite sign than the scores for short sleep. Habitual short sleep exhibits a signature on the human plasma metabolome which is different from medium and long sleep. However, we could not detect a direct link of this signature with obesity and diabetes risk.

New Metrics from Polysomnography: Precision Medicine for OSA Interventions

Obstructive sleep apnea (OSA) is a highly preventable disease accompanied by multiple comorbid conditions. Despite the well-established cardiovascular and neurocognitive sequelae with OSA, the optimal metric for assessing the OSA severity and response to therapy remains controversial. Although overnight polysomnography (PSG) is the golden standard for OSA diagnosis, the abundant information is not fully exploited. With the development of deep learning and the era of big data, new metrics derived from PSG have been validated in some OSA consequences and personalized treatment. In this review, these metrics are introduced based on the pathophysiological mechanisms of OSA and new technologies. Emphasis is laid on the advantages and the prognostic value against apnea-hypopnea index. New classification criteria should be established based on these metrics and other clinical characters for precision medicine.

Overall diet quality and proinflammatory diet in relation to risk of obstructive sleep apnea in 3 prospective US cohorts

BACKGROUND

Inflammation-related mechanisms may be important in the development of obstructive sleep apnea (OSA), and diet plays a crucial role in modulating inflammation. Current epidemiologic evidence for the associations between dietary patterns and OSA risk is limited to cross-sectional studies.

OBJECTIVES

We investigated prospectively the associations of overall diet quality and proinflammatory diet with OSA risk.

METHODS

We followed 145,801 participants in the Nurses' Health Study (NHS) (2002-2012), NHS II (1995-2013), and Health Professionals Follow-up Study (1996-2012). Alternative Healthy Eating Index 2010 (AHEI) and Empirical Dietary Inflammatory Pattern (EDIP) scores were calculated based on validated FFQs administered every 4 y. Cox models were used to estimate HRs and 95% CIs.

RESULTS

We documented 8856 incident OSA cases during follow-up. In pooled analyses adjusted for potential confounders, higher diet quality (higher AHEI scores) was associated with lower OSA risk (HR comparing the highest with the lowest quintile of AHEI: 0.76; 95% CI: 0.71, 0.82; P-trend < 0.001), and higher dietary inflammatory potential (higher EDIP scores) was associated with significantly increased risk (HR comparing the highest with the lowest quintile of EDIP: 1.94; 95% CI: 1.81, 2.08; P-trend < 0.001). Additional adjustment for metabolic factors attenuated both associations. The association with AHEI score was no longer statistically significant (comparable HR: 0.98; 95% CI: 0.91, 1.05; P-trend = 0.54), whereas the association with EDIP score remained statistically significant (comparable HR: 1.31; 95% CI: 1.22, 1.41; P-trend < 0.001).

CONCLUSIONS

A healthier diet, particularly one with anti-inflammatory potential, was associated with lower OSA risk.

Associations between sleep apnea risk and cardiovascular disease indicators among Chinese and Korean Americans

STUDY OBJECTIVES

While sleep apnea has been associated with cardiovascular disease (CVD) risk factors in white individuals in the U.S., these associations in Chinese and Korean Americans are less well-understood, particularly how these associations vary by age, gender, Asian origin, obesity, chronic conditions, and daytime sleepiness.

METHODS

We used a sample of Chinese and Korean Americans ages 50-75 (n = 394) from the Baltimore-Washington DC Metropolitan Area to examine the associations of high risk (HR) sleep apnea with diagnoseable hypercholesterolemia and diabetes, as well as the following biomarkers: total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), total cholesterol/HDL-C ratio, triglycerides, and glucose (non-fasting). Poisson models included demographic factors, socioeconomic status, and body mass index (BMI). We tested for potential effect modifiers.

RESULTS

HR-sleep apnea was associated with higher LDL-C level (β = 14.56, p < 0.05) and higher total cholesterol/HDL ratio (β = 0.64, p < 0.01). Younger respondents had higher levels of triglycerides associated with HR-sleep apnea than older respondents. For men, HR-sleep apnea was associated with higher total cholesterol, total cholesterol/HDL-C ratio, and triglycerides. Obese and overweight respondents had positive associations between HR-sleep apnea and total cholesterol, total cholesterol/HDL ratio, and triglycerides, while underweight/normal weight individuals did not. The interactions between snoring and daytime sleepiness were associated with hypercholesterolemia and diabetes.

CONCLUSIONS

This study demonstrates associations between sleep apnea risk and dyslipidemia among Chinese and Korean Americans. Associations were particularly pronounced among younger, male, overweight/obese, and sicker individuals. Future research should examine how to improve sleep health in Asian American populations to improve CVD risk.

Sleep Apnea and Cardiovascular Risk in Patients with Prediabetes and Type 2 Diabetes

Obstructive sleep apnea (OSA) is a common but largely undiagnosed clinical condition, which is turning into a serious public health issue. Of note is that its prevalence is gradually increasing in parallel with the obesity and type 2 diabetes mellitus (T2DM) epidemics. The aim of this article is to comprehensively review the literature in order to evaluate the cardiovascular (CV) risk among patients with OSA and prediabetes or T2DM. OSA seems to be an independent risk factor for the development as well as the progression of T2DM, whereas it is associated with T2DM-related macrovascular and microvascular complications. OSA may also act as a potential risk factor for the presentation and development of CV disease, such as hypertension, coronary artery disease, heart failure, pulmonary hypertension, atrial fibrillation and other cardiac arrythmias, as well as stroke. OSA and T2DM also share common pathophysiological mechanisms leading to atherosclerosis. Considering that the coexistence of OSA and T2DM is an independent and cumulative risk factor for CV mortality, more so than the two diseases separately, clinicians and healthcare professionals should be aware of and screen for OSA in patients with T2DM. Notably, targeted therapy for both conditions seems to substantially improve CV prognosis.

Validation of GOAL questionnaire as screening tool for clinical obstructive sleep apnea: A large sample study in China

Background

Obstructive sleep apnea (OSA) is a serious disease with a high prevalence in the general population. The purpose of this study is to explore the effectiveness of the GOAL questionnaire in the clinical screening of OSA and compare it with other existing screening tools.

Materials and methods

Outpatients and inpatients who underwent polysomnography (PSG) examination at the Sleep Medicine Center of the First Affiliated Hospital of Guangzhou Medical University from January 2013 to November 2016 were analyzed retrospectively. The basic data such as demographic, medical history, etc., and PSG data of the patients were collected, and the sensitivity, specificity, positive predictive value, negative predictive value and area under the curve (AUC) of GOAL and five other screening scales (the NoSAS score, Epworth Sleepiness Scale, the Berlin questionnaire, STOP, and STOP-Bang questionnaire) were calculated.

Results

Data from 2,171 participants (1,644 male; 78%) were analyzed there were 1,507 OSA patients [Apnea Hypopnea Index (AHI) ≥ 5 events/h] among them, accounting for about 69.415%. No matter which cut-off point (AHI ≥ 5, 15 and 30 events/h), the AUC score reveals that GOAL questionnaire had comparable screening ability to the NoSAS and STOP-BANG, and performed better than the ESS, and the AUC scores of the STOP questionnaire and Epworth Sleepiness Scale (ESS) were both lower than 0.7. When the cut-off point of the AHI was 5 events/h, the AUC of GOAL was the highest at 0.799 (0.781–0.816), and its sensitivity was the highest at 89.1%. The sensitivity levels of the NoSAS score and STOP-Bang questionnaire were 67.4 and 78.8% respectively, while ESS and the Berlin questionnaire have higher specificity (70.2 and 72.3% respectively) but lower sensitivity (49.3 and 60.0% respectively).

Conclusion

GOAL is a free, efficient and easy to manage tool with a screening ability comparable to NoSAS and STOP-Bang, and better than that of ESS.

Obstructive sleep apnea risk and its associated factors among type 2 diabetes mellitus patients at wolkite university specialized hospital, Wolkite, Southern Ethiopia, 2021. A comparative cross-sectional study

BACKGROUND

Obstructive sleep apnea is a syndrome characterized by recurrent partial, or complete upper airway collapse during sleep. Although obstructive sleep apnea is common in type 2 diabetes mellitus, the majority of patients remain undiagnosed because of the prohibitive cost of the test and paucity of the sleep clinic, especially in developing nations. The study aimed to assess high-risk obstructive sleep apnea and its associated factors among type 2 diabetes mellitus patients at Wolkite University Specialized Hospital.

METHODS

A Hospital-based comparative cross-sectional study was employed from October 15 to December 5, 2021, among 204 participants. Data collection was done by semi-structured interviewer-administered questionnaires. Data was entered into the Epi data version 4.6 and exported to SPSS version 25.0 for analysis. Independent t-test and chi-square test were used to compare continuous and categorical variables accordingly. Binary and multiple logistic regression analysis was used to assess factors associated with high-risk obstructive sleep apnea. Statistical significance was set at P-value < 0.05.

RESULTS

A total of 204 participants with an equal proportion of the two groups were included with a 100% response rate. About 56.9% of the participants were males. The mean age of type 2 diabetes mellitus patients was 57.1 (± 12.0) years and the non-diabetic group was 55.3 (± 10.9) years. The prevalence of high-risk obstructive sleep apnea among type 2 diabetes mellitus was 42.2%, and that of non-diabetics was 13.7% (p < 0.001). Age (AOR: 1.13; 95%CI: 1.04, 1.22), neck grasp (AOR: 6.48; 95%CI: 1.56, 26.96), waist circumference (AOR: 4.44; 95%CI: 1.12, 17.61) and the presence of diabetes-related complications (AOR: 4.18; 95%CI: 1.13, 15.43) were independently associated with high-risk obstructive sleep apnea among type 2 diabetes mellitus patients.

CONCLUSION

The prevalence of high-risk obstructive sleep apnea among type 2 diabetes mellitus was higher with a significant difference from their comparison group. Age, neck grasp, waist circumference, and diabetes-related complications were significantly associated with high-risk obstructive sleep apnea among type 2 diabetes mellitus patients. Therefore, type 2 diabetes mellitus patients should be screened for obstructive sleep apnea in the early course of their follow-up to take preventive measures and early treatments.

Insulin Resistance, Hyperglycemia, and Risk of Developing Obstructive Sleep Apnea in Men and Women in the United States

Rationale: Recent prospective studies suggest diabetes as a risk factor for the development of obstructive sleep apnea (OSA). However, the extent to which diabetes-related traits, such as hyperglycemia and insulin resistance, are related to OSA risk remains uncertain. Objectives: To examine the risk of developing OSA according to baseline concentrations of fasting insulin and hemoglobin A1c (HbA1c). Methods: Participants from four prospective U.S. cohorts were included: NHS (Nurses' Health Study; 2002-2012), NHSII (Nurses' Health Study II; 1995-2013), HPFS (Health Professionals Follow-up Study; 1996-2012), and MESA (Multi-Ethnic Study of Atherosclerosis; 2000-2012). OSA was assessed by self-reported clinical diagnosis in NHS/NHSII/HPFS and at-home polysomnography in MESA (defined as Apnea-Hypopnea Index ⩾30). Results: Of 9,283 participants with fasting insulin data, 790 (8.5%) developed OSA over 10 to 18 years of follow-up. After adjusting for sociodemographic, lifestyle, and comorbidity factors, the odds ratio for incident OSA comparing the extreme quintiles of fasting insulin was 3.59 (95% confidence interval, 2.67-4.82; P-trend < 0.0001). Of 6,342 participants with HbA1c data, 715 (11.3%) developed OSA. The comparable odds ratio for HbA1c was 2.21 (95% confidence interval, 1.69-2.89; P-trend < 0.0001). Additional adjustment for body mass index and waist circumference attenuated the associations for fasting insulin (P-trend = 0.005) and HbA1c (P-trend = 0.03). In the fully adjusted model simultaneously including both biomarkers, only fasting insulin but not HbA1c was associated with OSA risk. Conclusions: Independent of obesity, insulin resistance may play a more important role than hyperglycemia in the pathogenesis of OSA. Given the limitation of using self-reported diagnosis to exclude baseline prevalent OSA cases, additional studies are needed to further establish the temporal relationship and assess whether improving insulin resistance may reduce OSA risk.

Genetic determinants of cardiometabolic and pulmonary phenotypes and obstructive sleep apnoea in HCHS/SOL

BACKGROUND

Obstructive Sleep Apnoea (OSA) often co-occurs with cardiometabolic and pulmonary diseases. This study is to apply genetic analysis methods to explain the associations between OSA and related phenotypes.

METHODS

In the Hispanic Community Healthy Study/Study of Latinos, we estimated genetic correlations ρ_g between the respiratory event index (REI) and 54 anthropometric, glycemic, cardiometabolic, and pulmonary phenotypes. We used summary statistics from published genome-wide association studies to construct Polygenic Risk Scores (PRSs) representing the genetic basis of each correlated phenotype (ρ_g>0.2 and p-value<0.05), and of OSA. We studied the association of the PRSs of the correlated phenotypes with both REI and OSA (REI≥5), and the association of OSA PRS with the correlated phenotypes. Causal relationships were tested using Mendelian Randomization (MR) analysis.

FINDINGS

The dataset included 11,155 participants, 31.03% with OSA. 22 phenotypes were genetically correlated with REI. 10 PRSs covering obesity and fat distribution (BMI, WHR, WHRadjBMI), blood pressure (DBP, PP, MAP), glycaemic control (fasting insulin, HbA1c, HOMA-B) and insomnia were associated with REI and/or OSA. OSA PRS was associated with BMI, WHR, DBP and glycaemic traits (fasting insulin, HbA1c, HOMA-B and HOMA-IR). MR analysis identified robust causal effects of BMI and WHR on OSA, and probable causal effects of DBP, PP, and HbA1c on OSA/REI.

INTERPRETATION

There are shared genetic underpinnings of anthropometric, blood pressure, and glycaemic phenotypes with OSA, with evidence for causal relationships between some phenotypes.

FUNDING

Described in Acknowledgments.

The burden and risks of emerging complications of diabetes mellitus

The traditional complications of diabetes mellitus are well known and continue to pose a considerable burden on millions of people living with diabetes mellitus. However, advances in the management of diabetes mellitus and, consequently, longer life expectancies, have resulted in the emergence of evidence of the existence of a different set of lesser-acknowledged diabetes mellitus complications. With declining mortality from vascular disease, which once accounted for more than 50% of deaths amongst people with diabetes mellitus, cancer and dementia now comprise the leading causes of death in people with diabetes mellitus in some countries or regions. Additionally, studies have demonstrated notable links between diabetes mellitus and a broad range of comorbidities, including cognitive decline, functional disability, affective disorders, obstructive sleep apnoea and liver disease, and have refined our understanding of the association between diabetes mellitus and infection. However, no published review currently synthesizes this evidence to provide an in-depth discussion of the burden and risks of these emerging complications. This Review summarizes information from systematic reviews and major cohort studies regarding emerging complications of type 1 and type 2 diabetes mellitus to identify and quantify associations, highlight gaps and discrepancies in the evidence, and consider implications for the future management of diabetes mellitus.

Plasma polyunsaturated fatty acid concentrations and sleep apnea risk: A two-sample Mendelian randomization study

Background

Previous observational studies have found that lower levels of circulating polyunsaturated fatty acids (PUFAs) were associated with a higher risk of sleep apnea (SA). However, the causality of the association remains unclear.

Materials and methods

We used the two-sample Mendelian randomization (MR) study to assess the causal association of omega-3 and omega-6 fatty acids with SA. Single-nucleotide polymorphisms (SNPs) predicting the plasma level of PUFAs at the suggestive genome-wide significance level (p < 5 × 10^–6) were selected as instrumental variables (IVs) from the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) (n = ∼8,000) Consortium. For outcomes, the summary-level statistics of SA were obtained from the latest genome-wide association study (GWAS), which combined five cohorts with a total number of 25,008 SA cases and 172,050 snoring cases (total = 523,366).

Results

We found no association of α-linolenic acid (ALA) [odds ratio (OR) = 1.09 per% changed, 95% confidence interval (CI) 0.67–1.78], eicosapentaenoic acid (EPA) (OR = 0.94, 95% CI 0.88–1.01), docosapentaenoic acid (DPA) (OR = 0.95, 95% CI 0.88–1.02), and docosahexaenoic acid (DHA) (OR = 0.99, 95% CI 0.96–1.02) with the risk of SA using inverse-variance weighted (IVW) method. Moreover, for omega-6 PUFAs, no association between linoleic acid (LA) (OR = 0.98, 95% CI 0.96–1.01), arachidonic acid (AA) (1.00, 95% CI 0.99–1.01), and adrenic acid (AdrA) (0.93, 95% CI 0.71–1.21) with the risk of SA was found. Similarly, no associations of PUFAs with SA were found in single-locus MR analysis.

Conclusion

In the current study, we first found that there is no genetic evidence to support the causal role of omega-3 and omega-6 PUFAs in the risk of SA. From a public health perspective, our findings refute the notion that consumption of foods rich in PUFAs or the use of PUFAs supplementation can reduce the risk of SA.

The Clinical Effects of the Phlegm-Resolving Method in the Treatment of Obstructive Sleep Apnea-Hypopnea Syndrome: A Meta-Analysis of Randomized Controlled Trials

Objective

This study evaluated the clinical efficacy and safety of the phlegm-resolving method in traditional Chinese medicine (TCM) for the treatment of obstructive sleep apnea-hypopnea syndrome (OSAHS).

Methods

We searched the PubMed, Embase, Cochrane Library, Wanfang, CNKI, and VIP databases according to specific search strategies. The data were analyzed using RevMan 5.3 software.

Results

Thirteen randomized controlled trials (RCTs) comprising 882 patients with OSAHS were selected. Compared to continuous positive airway pressure (CPAP), the phlegm-resolving method of TCM combined with CPAP significantly more effectively improved the apnea/hypopnea index (AHI), Epworth Sleepiness Scale (ESS), and lowest oxygen saturation (LSaO₂). While the treatment effect was better for a treatment duration of >6 weeks compared to that at ≤6 weeks, the difference was not statistically significant. Compared to health guidance alone, the combination of the phlegm-resolving method in TCM with health guidance showed significantly better efficacy in improving AHI, ESS, and LSaO₂. In terms of reducing ESS and increasing LSaO₂, the effect was better for treatment courses >6 weeks. When the AHI was reduced, a duration of ≤6 weeks showed more advantages; however, the difference was not significant. Only one study reported mild nausea in one participant in the treatment group at the initial stage of treatment; the remaining studies did not mention any side effects.

Conclusion

Both the resolving phlegm method of TCM combined with CPAP and the resolving phlegm method of TCM combined with health guidance were more effective in improving AHI, LSaO₂, and ESS compared to the control group.

Associations of Chronic Diabetes Complications and Cardiovascular Risk with the Risk of Obstructive Sleep Apnea in Patients with Type 2 Diabetes

Background: Type 2 diabetes mellitus (T2DM) is associated with increased mortality and morbidity, including cardiovascular diseases and obstructive sleep apnea (OSA). The aim of this study was to assess the associations between cardiovascular risk, chronic diabetes complications and the risk of OSA in adult patients with T2DM. Methods: The study included 529 patients with T2DM in whom moderate-to-severe OSA risk was assessed using the STOP-Bang questionnaire, dividing the subjects into two groups: group 1: STOP-Bang score <5, and group 2: STOP-Bang score ≥5, respectively. In all the subjects, cardiovascular risk was assessed using the UKPDS risk engine. Statistical analysis was performed using SPSS 26.0, the results being statistically significant if p value was <0.05. Results: 59% of the subjects scored ≥5 on the STOP-Bang questionnaire. We recorded statistically significant differences between the two groups regarding diabetes duration, HbA1c, HOMA-IR, albuminuria, as well as cardiovascular risk at 10 years for both coronary heart disease (CHD) and stroke (p < 0.05). Furthermore, through logistic regression, adjusting for confounding factors, we demonstrated that the STOP-Bang score ≥ 5 is a risk factor for 10-year fatal and nonfatal CHD risk. Conclusions: It is extremely important to screen and diagnose OSA in patients with T2DM, in order to improve the primary and secondary prevention of cardiovascular events in these patients.

Bidirectional relationships of comorbidity with obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is frequently associated with comorbidities that include metabolic, cardiovascular, renal, pulmonary and neuropsychiatric. There is considerable evidence that OSA is an independent risk factor for many of these comorbidities but, more recently, there is evidence that some of these comorbidities may predispose to the development of OSA. Thus, there is growing evidence of a bidirectional relationship between OSA and comorbidity, especially for heart failure, metabolic syndrome and stroke. Potential mechanisms of bidirectional relationships differ in individual comorbidities with fluid retention and redistribution being especially important in heart failure and end-stage renal disease, whereas neural mechanisms may be more important in diabetes mellitus and stroke. The evidence for other comorbidities, such as hypertension and atrial fibrillation, support these being more a consequence of OSA with limited evidence to support a bidirectional relationship. The present review explores the evidence for such bidirectional relationships with a particular perspective on comorbidities that may predispose to OSA. The impact of therapy in bidirectional relationships is also reviewed, which highlights the clinical importance of accurate diagnosis. This aspect is especially true of COPD, where the identification of co-existing OSA has important implications for optimum therapy.

Obstructive sleep apnoea (OSA) is an independent risk factor for comorbidity, especially cardiometabolic. However, some comorbidities may be risk factors for OSA, supporting a bidirectional relationship that may have important implications for treatment.https://bit.ly/3BbJy6V

Advances in the study of OSA and diabetic foot

Diabetic foot is one of the most serious and painful chronic complications of diabetic patients, especially elderly diabetic patients. It has a high rate of death, disability and amputation. Obstructive sleep apnea (OSA) is a treatable chronic sleep disorder. Existing evidence suggests that OSA may promote the development and delay the healing of diabetic foot, and continuous positive airway pressure therapy may promote the healing of ulcers. Therefore, in the multidisciplinary diagnosis and treatment of diabetes, cooperation with sleep medicine should be strengthened, and the basic and clinical research on diabetic foot combined with OSA should be strengthened, so as to reduce the amputation rate, improve the cure rate and reduce the incidence of cardiovascular events.

The association between type 2 diabetes and major depression in apnoeic individuals

Given the few studies available in the literature, the aim of this study was to investigate the association between type 2 diabetes and major depression in a large sample of apnoeic individuals. Demographic and polysomnographic data from 395 apnoeic individuals recruited from the clinical database of the Erasme Hospital Sleep Laboratory were analysed. Only individuals with a diagnosis of type 2 diabetes according to the diagnostic criteria of the American Diabetes Association at admission were included in the "diabetes" group. Logistic regression analyses were used to study the association between type 2 diabetes and major depression in apnoeic individuals. The prevalence of type 2 diabetes was 19.7% in our sample of apnoeic individuals. After adjusting for major confounding factors, multivariate logistic regression analyses demonstrated that unlike remitted major depression and mild major depression, only moderate to severe major depression was significantly associated with higher likelihood of type 2 diabetes in apnoeic individuals. In our study, we found that moderate to severe major depression is significantly associated with type 2 diabetes in apnoeic individuals, which seems to justify more systematic screening and adequate therapeutic management of this psychiatric disorder to allow better glycaemic control in this subpopulation at high risk of diabetic micro/macrovascular complications.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41105-021-00359-0.

Prevalence and factors associated with atrial fibrillation in older patients with obstructive sleep apnea

Purpose

This study sought to identify the prevalence and factors associated with atrial fibrillation (AF) in older patients with obstructive sleep apnea (OSA) in China. 

Methods

This was an explorative cross-sectional study. Between January 2015 and October 2017, we continuously recruited 1285 older patients with OSA who underwent overnight polysomnography from sleep centers of multiple hospitals. They were assessed using 12-lead ECG or 24-h dynamic ECG, and their baseline demographics, clinical characteristics, sleep parameters, and medical history were determined. Multivariate binary logistic regression analysis was used to investigate the factors related to AF in these older patients with OSA.

Results

The clinician classified 122 (9.5%) patients as having AF. The prevalence of AF significantly increased with age (P < 0.05) but did not significantly differ between the mild, moderate, and severe OSA groups. Additionally, the prevalence of paroxysmal AF was 7.2% among the overall study population, and it increased with OSA severity or advanced age (P < 0.05). Persistent AF was noted in 2.3% participants, and the prevalence also increased with age. The logistic regression analysis showed that age (OR = 1.054, 95%CI: 1.027–1.018, P < 0.001), history of drinking (OR = 1.752, 95%CI: 1.070–2.867, P < 0.05), chronic heart disease (OR = 1.778, 95%CI: 1.156–2.736, P < 0.01), diabetes mellitus (OR = 1.792, 95%CI: 1.183–2.713, P < 0.01), and reduced diastolic function (OR = 2.373, 95%CI = 1.298–4.337, P < 0.01) were relevant to AF among participants with OSA.

Conclusion

The prevalence of AF is significantly common in older patients with OSA. Age, history of drinking, chronic heart disease, diabetes mellitus, and reduced diastolic function are independently related to AF in these patients.

Prediabetes Is Associated with Increased Prevalence of Sleep-Disordered Breathing

Type 2 diabetes leads to severe nocturnal hypoxemia, with an increase in apnea events and daytime sleepiness. Hence, we assessed sleep breathing parameters in the prediabetes stage. A cross-sectional study conducted on 966 middle-aged subjects without known pulmonary disease (311 patients with prediabetes and 655 controls with normal glucose metabolism) was conducted. Prediabetes was defined by glycated hemoglobin (HbA1c), and a nonattended overnight home sleep study was performed. Participants with prediabetes (n = 311) displayed a higher apnea−hypopnea index (AHI: 12.7 (6.1;24.3) vs. 9.5 (4.2;19.6) events/h, p < 0.001) and hypopnea index (HI: 8.4 (4.0;14.9) vs. 6.0 (2.7;12.6) events/h, p < 0.001) than controls, without differences in the apnea index. Altogether, the prevalence of obstructive sleep apnea was higher in subjects with prediabetes than in controls (78.1 vs. 69.9%, p = 0.007). Additionally, subjects with prediabetes presented impaired measurements of the median and minimum nocturnal oxygen saturation, the percentage of time spent with oxygen saturations below 90%, and the 4% oxygen desaturation index in comparison with individuals without prediabetes (p < 0.001 for all). After adjusting for age, sex, and the presence of obesity, HbA1c correlated with the HI in the entire population (r = 0.141, p < 0.001), and the presence of prediabetes was independently associated with the AHI (B = 2.20 (0.10 to 4.31), p = 0.040) as well as the HI (B = 1.87 (0.61 to 3.14), p = 0.004) in the multiple linear regression model. We conclude that prediabetes is an independent risk factor for an increased AHI after adjusting for age, sex, and obesity. The enhanced AHI is mainly associated with increments in the hypopnea events.

Diabetes and cardiovascular diseases are associated with the worsening of intermittent hypoxaemia

Intermittent hypoxaemia is a risk factor for numerous diseases. However, the reverse pathway remains unclear. Therefore, we investigated whether pre-existing hypertension, diabetes or cardiovascular diseases are associated with the worsening of intermittent hypoxaemia. Among the included 2,535 Sleep Heart Health Study participants, hypertension (n = 1,164), diabetes (n = 170) and cardiovascular diseases (n = 265) were frequently present at baseline. All participants had undergone two polysomnographic recordings approximately 5.2 years apart. Covariate-adjusted linear regression analyses were utilized to investigate the difference in the severity of intermittent hypoxaemia at baseline between each comorbidity group and the group of participants free from all comorbidities (n = 1,264). Similarly, we investigated whether the pre-existing comorbidities are associated with the progression of intermittent hypoxaemia. Significantly higher oxygen desaturation index (β = 1.77 [95% confidence interval: 0.41-3.13], p = 0.011), desaturation severity (β = 0.07 [95% confidence interval: 0.00-0.14], p = 0.048) and desaturation duration (β = 1.50 [95% confidence interval: 0.31-2.69], p = 0.013) were observed in participants with pre-existing cardiovascular diseases at baseline. Furthermore, the increase in oxygen desaturation index (β = 3.59 [95% confidence interval: 1.78-5.39], p < 0.001), desaturation severity (β = 0.08 [95% confidence interval: 0.02-0.14], p = 0.015) and desaturation duration (β = 2.60 [95% confidence interval: 1.22-3.98], p < 0.001) during the follow-up were higher among participants with diabetes. Similarly, the increase in oxygen desaturation index (β = 2.73 [95% confidence interval: 1.15-4.32], p = 0.001) and desaturation duration (β = 1.85 [95% confidence interval: 0.62-3.08], p = 0.003) were higher among participants with cardiovascular diseases. These results suggest that patients with pre-existing diabetes or cardiovascular diseases are at increased risk for an expedited worsening of intermittent hypoxaemia. As intermittent hypoxaemia is an essential feature of sleep apnea, these patients could benefit from the screening and follow-up monitoring of sleep apnea.