Obstructive sleep apnoea syndrome, plasma adiponectin levels, and insulin resistance

Sleep apnea and eye diseases: evidence of association and potential pathogenic mechanisms

Eye diseases are an important group of increasingly prevalent disorders that contribute very significantly to disability and represent a considerable health burden. Some data suggest that several of these diseases may be associated with sleep-disordered breathing, mainly obstructive sleep apnea (OSA), due to intermediate mechanisms, such as intermittent hypoxia or sleep fragmentation. The aims of this systematic review were to identify and critically evaluate the current evidence supporting the existence of a possible relationship between OSA and the more relevant eye diseases as well as to evaluate the potential pathogenic mechanisms. There is a body of largely low-level evidence for the association of OSA with glaucoma, nonarteritic ischemic optic neuropathy, central serous chorioretinopathy, and diabetic retinopathy. Meta-analysis of available case-control studies shows that OSA increases the risk of glaucoma (pooled odds ratio: 1.50; 95% confidence interval: 1.25 to 1.80; P < .001), nonarteritic ischemic optic neuropathy (3.62; 1.94 to 6.76; P < .001), and diabetic retinopathy (1.57; 1.09 to 2.27; P = .02). Moreover, several pathogenic pathways have been identified, mainly related to hypoxic damage, mechanical stress, systemic inflammation, oxidative stress, sympathetic tone, and endothelial dysfunction. In contrast, information about the effect of apnea-hypopnea suppression on the development and progression of eye damage is either nonexistent or of a very low level of evidence. In conclusion, OSA has emerged as an additional potential risk factor for many eye diseases, although their link is weak and contradictory, so further examination is required.

CITATION

García-Sánchez A, Villalaín I, Asencio M, García J, García-Rio F. Sleep apnea and eye diseases: evidence of association and potential pathogenic mechanisms. J Clin Sleep Med. 2022;18(1):265-278.

Obstructive sleep apnea and cardiovascular comorbidity: common pathophysiological mechanisms to cardiovascular disease

Obstructive sleep apnea (OSA) is associated with many cardiovascular and metabolic diseases. Sleep apnea causes intermittent hypoxemia, chest pressure fluctuations and a reaction from the cerebral cortex in the form of a short awakening during sleep (EEG-activation). The consequences of pathological pathways are studied in experimental models involving cell cultures, animals, and healthy volunteers. At present, the negative impact of intermittent hypoxemia on a variety of pathophysiological disorders of the heart and blood vessels (vascular tone fluctuations, thickening of the intimamedia complex in the vascular wall, direct damaging effect on the myocardium) has a great evidence base. Two other pathological components of OSA (pressure fluctuations and EEG-activation) can also affect cardiovascular system, mainly affecting the increase in blood pressure and changing cardiac hemodynamics. Although these reactions are considered separately in the review, with the development of sleep apnea they occur sequentially and are closely interrelated. As a result, these pathological pathways trigger further pathophysiological mechanisms acting on the heart and blood vessels. It is known that these include excessive sympathetic activation, inflammation, oxidative stress and metabolic dysregulation. In many respects being links of one process, these mechanisms can trigger damage to the vascular wall, contributing to the formation of atherosclerotic lesions. The accumulated data with varying degrees of reliability confirm the participation of OSA through these processes in the formation of cardiovascular disorders. There are factors limiting direct evidence of this interaction (sleep deprivation, causing similar changes, as well as the inability to share the contribution of other risk factors for cardiovascular diseases, in particular arterial hypertension, obesity, which are often associated with OSA). It is necessary to continue the study of processes that implement the pathological effect of OSA on the cardiovascular system.

Obesity, malnutrition, and trace element deficiency in the coronavirus disease (COVID-19) pandemic: An overview

The world is currently facing the coronavirus disease (COVID-19) pandemic which places great pressure on health care systems and workers, often presents with severe clinical features, and sometimes requires admission into intensive care units. Derangements in nutritional status, both for obesity and malnutrition, are relevant for the clinical outcome in acute illness. Systemic inflammation, immune system impairment, sarcopenia, and preexisting associated conditions, such as respiratory, cardiovascular, and metabolic diseases related to obesity, could act as crucial factors linking nutritional status and the course and outcome of COVID-19. Nevertheless, vitamins and trace elements play an essential role in modulating immune response and inflammatory status. Overall, evaluation of the patient's nutritional status is not negligible for its implications on susceptibility, course, severity, and responsiveness to therapies, in order to perform a tailored nutritional intervention as an integral part of the treatment of patients with COVID-19. The aim of this study was to review the current data on the relevance of nutritional status, including trace elements and vitamin status, in influencing the course and outcome of the disease 3 mo after the World Health Organization's declaration of COVID-19 as a pandemic.

Obstructive sleep apnea in patients with diabetes less than 40 years of age

BACKGROUND AND AIM

Obstructive sleep apnea (OSA) is known to be associated with diabetes mellitus (DM). Age is factor associated with different clinical features of OSA. There is limited data on clinical differences of young DM patients with OSA versus older DM patients with OSA. This study aimed to find clinical differences of DM coexisting with OSA between young age group and older.

METHODS

This is a retrospective, analytical study conducted at Srinagarind Hospital, Thailand. The inclusion criteria were adult patients diagnosed as DM with OSA. The study period was between January 2008 and December 2019. The diagnosis of OSA was made by presence of apnea hypopnea index (AHI) of ≥5 times/hour by polysomnography. Clinical predictors of OSA in young DM patients with age under 40 years were executed.

RESULTS

There were 56 patients in the young diabetes mellitus group, while there were 137 patients in the older diabetes mellitus group. The mean (SD) age of diagnosis for diabetes mellitus of both groups were 31.61 (6.53) and 54.68 (7.62) years, respectively. There were three independent predictors for DM in the young: atrial fibrillation (AF), body mass index (BMI) and glomerular filtration rate (GFR). Presence of AF perfectly predicted DM with OSA in age over 40 years. The adjusted odds ratio for BMI and GFR were 1.29 (95% CI 1.05, 1.58) and 1.06 (1.01, 1.13). The BMI over 32 kg/m² and GFR over 77 ml/min/m² gave sensitivity of 80.00%.

CONCLUSIONS

Young DM patients with OSA had more severe OSA, were more obese, had better renal function, and had fewer AF than the older ones.

Severity Indices for Obstructive Sleep Apnea Syndrome Reflecting Glycemic Control or Insulin Resistance

Objective We aimed to identify obstructive sleep apnea syndrome (OSAS) severity indices reflecting the anthropometric and metabolic characteristics of patients with OSAS. Methods A total of 76 patients with OSAS underwent nasal continuous positive airway pressure (nCPAP). We also investigated the effects of nCPAP on OSAS-associated muscle sympathetic nerve activity (MSNA), risk for cardiovascular diseases, and insulin secretion and sensitivity. Results Among the OSAS severity indices, HbA1c was significantly correlated with the apnea-hypopnea index, whereas HOMA-beta, HOMA-IR, and hepatic insulin resistance were significantly correlated with % SpO₂<90%, independent of age, gender, and body mass index (BMI). Burst incidence of MSNA was independently associated with only a 3% oxygen desaturation index. nCPAP therapy significantly lowered the OSAS severity indices and reduced the burst rate, burst incidence, and heart rate. Conclusion The OSAS severity indices reflecting apnea/hypopnea are associated with glycemic control, whereas those reflecting hypoxia, particularly % SpO₂<90%, are associated with hepatic insulin resistance independent of obesity. Both types of OSAS severity indices, especially the 3% oxygen desaturation index (reflecting intermittent hypoxia), are independently associated with MSNA, which is dramatically lowered with the use of nCPAP therapy. These findings may aid in interpreting each OSAS severity index and understanding the pathophysiology of OSAS in clinical settings.

Leptin and adiponectin levels in obstructive sleep apnea phenotypes

Objective: To examine the serum levels of leptin and adiponectin in different obstructive sleep apnea (OSA) phenotypes. Methods: Obese patients who were admitted to our sleep laboratory were included. All patients underwent spirometry, daytime arterial blood gas analysis, polysomnography and transthoracic echocardiography. Serum levels of adiponectin and leptin were recorded. Results: Analysis included 146 OSA patients (81 females, 65 males, age: 49.8 ± 10.7 years, body mass index: 40.3 ± 4.9 kg/m², 47.9% severe OSA, 42.5% severe obesity). Females had higher leptin and adiponectin levels (p < 0.001; p < 0.001, respectively). Leptin levels were higher in patients with severe obesity (p < 0.001). Severe OSA patients had lower leptin and adiponectin levels (p = 0.023; p = 0.035, respectively). Conclusion: Adipokine levels were different especially in OSA patients with severe obesity, female gender and severe OSA.

Clinical Characteristics of Type 2 Diabetics Who are at High Risk for Obstructive Sleep Apnea

Introduction:

Obstructive sleep apnea (OSA) has been associated with insulin resistance and glucose intolerance. Recent reports have indicated that the majority of patients with type 2 diabetes (T2D) are also having OSA.

Aim/Objective:

The primary goal of the study is to assess the risk of OSA among T2D patients and its impact on T2D related control and complications.

Method:

A cross-sectional study for the adult patients with T2D who had a routine follow up visit from Jun 2013- Aug 2014 was asked to participate. We excluded patients with existed psychiatric illness and those with history of diagnosed OSA. To screen for OSA we used Berlin Questionnaire.

Result:

A total of 265 T2D patients were included in the study with a mean age of 57.2+12.5 years and long standing T2D. Around 53.2% were classified as high risk for OSA. Compared to those who are considered low risk for OSA, those who are high risk for OSA have higher BMI (p <0.001), higher mean SBP (p 0.002), less likely to be male (p 0.003), more likely to have hyperlipidemia (p 0.058), more likely have neuropathy (p 0.021), more likely to report sedentary lifestyle (p 0.046), and more likely to report low income (p 0.068).

Conclusion:

High risk T2D patients for OSA tend to be older, have significantly higher BMI, systolic BP and tend to have significantly higher risk for neuropathy.

The Bidirectional Relationship Between Obstructive Sleep Apnea and Metabolic Disease

Obstructive sleep apnea (OSA) is a common sleep disorder, effecting 17% of the total population and 40-70% of the obese population (1, 2). Multiple studies have identified OSA as a critical risk factor for the development of obesity, diabetes, and cardiovascular diseases (3-5). Moreover, emerging evidence indicates that metabolic disorders can exacerbate OSA, creating a bidirectional relationship between OSA and metabolic physiology. In this review, we explore the relationship between glycemic control, insulin, and leptin as both contributing factors and products of OSA. We conclude that while insulin and leptin action may contribute to the development of OSA, further research is required to determine the mechanistic actions and relative contributions independent of body weight. In addition to increasing our understanding of the etiology, further research into the physiological mechanisms underlying OSA can lead to the development of improved treatment options for individuals with OSA.

Obesity metabolic and hormonal disorders associated with obstructive sleep apnea and their impact on the risk of cardiovascular events

OBJECTIVE

To analyze metabolic and hormonal disorders resulting from the association between obesity and obstructive sleep apnea (OSA) syndrome that predispose to cardiovascular diseases and investigate the clinical benefits obtained from treatment approaches for both conditions.

METHODS

A literature review between 1997 and 2017 was conducted in the PubMed search database.

RESULTS

Obesity is the most important risk factor for OSA, and the progressive increase in its prevalence also affects OSA incidence. In addition, OSA may aggravate weight gain and obesity comorbidities. Both conditions lead to an increase in the risk of cardiovascular events and mortality. The gold standard treatment for moderate to severe OSA is CPAP, but significant reduction in major cardiovascular events was not observed in clinical trials. Body weight reduction appears effective to improve OSA, as long as it is maintained. Lifestyle modifications and drug therapy seem to be the preferred approach to treat obesity, but in severe obesity and moderate to severe OSA, bariatric surgery is probably the most adequate treatment.

CONCLUSIONS

Weight control is essential to decrease the risk of cardiovascular events and mortality potentially linked to both obesity and OSA. CPAP seems to treat only OSA without decreasing these risks. Other treatment strategies are lifestyle modifications and drug therapy, which need further investigation as well as bariatric surgery for severe cases.

Association between nighttime sleep duration, midday naps, and glycemic levels in Japanese patients with type 2 diabetes

OBJECTIVES

To clarify the relationship between nighttime sleep duration, midday naps, and glycemic control in Japanese patients diagnosed with type 2 diabetes (n = 355) or impaired glucose tolerance (n = 43).

METHODS

A total of 398 patients completed a self-administered questionnaire on sleep duration/quality and were divided into five groups according to their self-reported nighttime sleep duration: <5 h, 5-6 h, 6-7 h, 7-8 h, and >8 h. Each group was further divided into two subgroups each according to the presence or absence of midday naps. Poor glycemic control was defined as HbA1c ≥ 7.0%.

RESULTS

Short nighttime sleep (<5 h), poor sleep induction, daytime sleepiness, and low sleep satisfaction were associated with high HbA1c levels. HbA1c was higher in the short nighttime sleep/no nap group than in non-nappers with different nighttime sleep duration, whereas the short nighttime sleep/nap group showed similar HbA1c levels to the other nap subgroups. In multivariate logistic regression models, after adjusting for a number of potential confounders, short (<5 h) nighttime sleep without nap was significantly associated with poor glycemic control compared with 6-7 h nighttime sleep without nap (OR [95% CI]: 7.14 [2.20-23.20]). However, taking naps reduced this risk for poor glycemic control in short sleepers. Other risk factors for poor glycemic control were low sleep satisfaction (1.73 [1.10-2.70]) and poor sleep induction (1.69 [1.14-2.50]).

CONCLUSIONS

Poor sleep quality and quantity could aggravate glycemic control in type 2 diabetes. Midday naps could mitigate the deleterious effects of short nighttime sleep on glycemic control.

CLINICAL TRIALS REGISTRATION

UMIN 000017887.

Sleep Duration and Diabetes Risk: Population Trends and Potential Mechanisms

Sleep is important for regulating many physiologic functions that relate to metabolism. Because of this, there is substantial evidence to suggest that sleep habits and sleep disorders are related to diabetes risk. In specific, insufficient sleep duration and/or sleep restriction in the laboratory, poor sleep quality, and sleep disorders such as insomnia and sleep apnea have all been associated with diabetes risk. This research spans epidemiologic and laboratory studies. Both physiologic mechanisms such as insulin resistance, decreased leptin, and increased ghrelin and inflammation and behavioral mechanisms such as increased food intake, impaired decision-making, and increased likelihood of other behavioral risk factors such as smoking, sedentary behavior, and alcohol use predispose to both diabetes and obesity, which itself is an important diabetes risk factor. This review describes the evidence linking sleep and diabetes risk at the population and laboratory levels.

Obstructive sleep apnea is associated with fatty liver index, the index of nonalcoholic fatty liver disease

BACKGROUND AND OBJECTIVES

The relationship between obstructive sleep apnea (OSA) and nonalcoholic fatty liver disease (NAFLD) is gaining increased attention. The aim of the present study was to examine the relationship of OSA with NAFLD defined by an elevated fatty liver index (FLI).

MATERIALS AND METHODS

A total of 319 consecutive patients who underwent standard polysomnography were enrolled. Fasting blood samples were obtained from all patients for biological profile measurements, and demographic data were collected. Values of FLI were determined and assessed as predictors of the presence of NAFLD, as measured by ultrasound. The discriminative ability of FLI was estimated on the basis of the area under the receiver operator characteristic curve.

RESULTS

An FLI of 60 achieved the highest diagnostic accuracy and yielded an area under the receiver operator characteristic curve of 0.822 (95% confidence interval: 0.729-0.916) in the detection of NAFLD. Patients with an FLI of 60 or higher had a significantly lower lowest O2 saturation (73 vs. 83%, P<0.001), a lower mean nocturnal oxygen saturation (93 vs. 95%, P<0.001), a higher apnea-hypopnea index (39.7 vs. 18.4, P<0.001), a higher oxygen desaturation index (39 vs. 10.6, P<0.001), and a higher percentage of sleep time spent with SpO2 less than 90% (4.63 vs. 0.92%, P<0.001) compared with those with FLI less than 60. In multivariate analysis, the presence of OSA was independently associated with elevated FLI after adjusting for confounding factors (odds ratio: 5.141, 95% confidence interval: 1.414-18.696, P=0.013).

CONCLUSION

Our results suggest a positive association between the severity of OSA and NAFLD defined by an elevated FLI, which may serve as a good biomarker for detecting NAFLD in OSA patients.

Serum triglyceride levels in relation to high-density lipoprotein cholesterol (TG-HDL) ratios as an efficient tool to estimate the risk of sleep apnea syndrome in non-overweight Japanese men

OBJECTIVES

Several studies have reported the association between sleep apnea syndrome and insulin resistance. Being overweight is known risk factor both for sleep apnea syndrome and insulin resistance. However, no studies have reported on the association between serum triglyceride levels in relation to high-density lipoprotein cholesterol (TG-HDL) ratios (a marker of insulin resistance) and sleep apnea syndrome accounting for body mass index (BMI) status.

METHODS

Subjects for the present cross-sectional study consisted of 1,528 men aged 30-69 years undergoing pulse oximetry at a sleep disorders clinic for sleep apnea syndrome. Sleep apnea syndrome was diagnosed as a 3 % oxygen desaturation index (ODI) of ≥15 events/h.

RESULTS

Among study participants, 241 men were diagnosed with sleep apnea syndrome. Independent of classical cardiovascular risk factors, TG-HDL was significantly positively associated with sleep apnea syndrome in participants with a BMI <25 kg/m², but not in participants with a BMI ≥25 kg/m². The multivariable adjusted odds ratio (OR) and 95 % confidence interval (95 % CI) of sleep apnea syndrome per Log TG-HDL was 2.03 (95 % CI: 1.36-3.03) for a BMI <25 kg/m² and 1.23 (95 % CI: 0.89-1.70) for a BMI ≥25 kg/m².

CONCLUSIONS

An independent positive association between TG-HDL levels and risk of sleep apnea syndrome was observed in participants with a BMI of <25 kg/m², but not in participants with a BMI ≥25 kg/m². TG-HDL levels could be an efficient tool to estimate the risk of sleep apnea syndrome in non-overweight Japanese men.

Serum adiponectin level in obstructive sleep apnea: Relation of adiponectin to obesity and long-term continuous positive airway pressure therapy

PURPOSE

The study aimed to determine the effect of OSA and obesity on the plasma levels of adiponectin and the long-term effect of CPAP on its plasma levels and obesity parameters.

MATERIAL/METHODS

A prospective observational study included 159 newly diagnosed OSA patients. The cohort was divided into CPAP treated (n=82) and control group (n=77). Both groups were examined at the beginning and a year later. The CPAP-treated patients were additionally tested after a month of therapy. The examinations included Epworth Sleepiness Scale questionnaire, anthropometric and polysomnographic measurements, and blood serum tests. Changes in the studied parameters of OSA, obesity, and adiponectin obtained at the beginning and after follow-up period were compared in each group.

RESULTS

In CPAP group, all studied OSA parameters improved already after a month of CPAP therapy. Contrarily, obesity parameters (except of neck and waist circumference) remained unchanged after CPAP therapy. Serum adiponectin levels dropped during CPAP therapy. In the control group, both obesity and OSA parameters did not show changes. The only exceptions were deteriorated mean SpO2 and decreased hip circumference. Adiponectin remained unchanged in this group. In neither group, the Spearman correlation analyses showed any association of serum adiponectin levels with obesity or OSA parameters, except of mean SpO2.

CONCLUSIONS

Only correlation found was between adiponectin and mean SpO2. Although CPAP therapy improves all OSA parameters, it did not change most obesity parameters. Additionally in the CPAP group, there was a significant drop in adiponectin levels, suggesting its protective role in this group of patients.

OSAS-related inflammatory mechanisms of liver injury in nonalcoholic fatty liver disease

Obstructive sleep apnoea syndrome (OSAS) is a common sleep disorder, affecting over 4% of the general population, and is associated with metabolic syndrome and cardiovascular disease, independent of obesity and traditional risk factors. OSAS has been recently connected to nonalcoholic fatty liver disease (NAFLD), the most common chronic liver disease in the world, which can be found in 30% of the general adult population. Several studies suggest that the chronic intermittent hypoxia (CIH) of OSAS patients may per se trigger liver injury, inflammation, and fibrogenesis, promoting NAFLD development and the progression from steatosis to steatohepatitis, cirrhosis, and hepatocellular carcinoma. In NAFLD patients, liver disease may be caused by hypoxia both indirectly by promoting inflammation and insulin resistance and directly by enhancing proinflammatory cytokine production and metabolic dysregulation in liver cells. In this review, we focus on molecular mechanisms linking OSAS to NAFLD, including hypoxia inducible factor (HIF), nuclear factor kappa B (NF-κB), YKL-40, unfolded protein response, and hypoxic adipose tissue inflammation, which all could provide novel potential therapeutic approaches for the management of NAFLD patients with OSAS.

Obstructive sleep apnoea, insulin resistance and adipocytokines

Obstructive sleep apnoea (OSA) is associated with multiple cardiometabolic abnormalities. Obesity is considered a major risk factor for the development of OSA, and it is also an established risk factor for insulin resistance and other cardiometabolic disorders. The enigma remains whether OSA has any causal role in the adverse metabolic profile, independent of or beyond that due to obesity. Sleep apnoeas and hypopnoeas result directly in intermittent hypoxaemia and cerebral arousals, both of which may evoke a cascade of downstream biologic responses in various body tissues and cells. Adipose tissue is a major source of adipocytokines many of which play important roles in the regulation of various metabolic functions. It is hypothesized that OSA may, through its unique pathophysiology, affect metabolic function through modulation of production or action of adipocytokines. This review focuses on insulin resistance, glucose metabolism and relevant adipocytokines in the context of OSA.

Diagnostic capability of biological markers in assessment of obstructive sleep apnea: a systematic review and meta-analysis

OBJECTIVE

The purpose of this systematic review is to evaluate the diagnostic value of biological markers (exhaled breath condensate, blood, salivary and urinary) in the diagnosis of OSA in comparison to the gold standard of nocturnal PSG.

METHODS

Studies that differentiated OSA from controls based on PSG results, without age restriction, were eligible for inclusion. The sample of selected studies could include studies in obese patients and with known cardiac disease. A detailed individual search strategy for each of the following bibliographic databases was developed: Cochrane, EMBASE, MEDLINE, PubMed, and LILACS. The references cited in these articles were also crosschecked and a partial grey literature search was undertaken using Google Scholar. The methodology of selected studies was evaluated using the 14-item Quality Assessment Tool for Diagnostic Accuracy Studies.

RESULTS

After a two-step selection process, nine articles were identified and subjected to qualitative and quantitative analyses. Among them, only one study conducted in children and one in adults found biomarkers that exhibit sufficiently satisfactory diagnostic accuracy that enables application as a diagnostic method for OSA.

CONCLUSION

Kallikrein-1, uromodulin, urocotin-3, and orosomucoid-1 when combined have enough accuracy to be an OSA diagnostic test in children. IL-6 and IL-10 plasma levels have potential to be good biomarkers in identifying or excluding the presence of OSA in adults.

Biomarkers associated with obstructive sleep apnea: A scoping review

The overall validity of biomarkers in the diagnosis of obstructive sleep apnea (OSA) remains unclear. We conducted a scoping review to provide assessments of biomarkers characteristics in the context of obstructive sleep apnea (OSA) and to identify gaps in the literature. A scoping review of studies in humans without age restriction that evaluated the potential diagnostic value of biological markers (blood, exhaled breath condensate, salivary, and urinary) in the OSA diagnosis was undertaken. Retained articles were those focused on the identification of biomarkers in subjects with OSA, the latter being confirmed with a full overnight or home-based polysomnography (PSG). Search strategies for six different databases were developed. The methodology of selected studies was classified using an adaptation of the evidence quality criteria from the American Academy of Pediatrics. Additionally the biomarkers were classified according to their potential clinical application. We identified 572 relevant studies, of which 117 met the inclusion criteria. Eighty-two studies were conducted in adults, 34 studies involved children, and one study had a sample composed of both adults and children. Most of the studies evaluated blood biomarkers. Potential diagnostic biomarkers were found in nine pediatric studies and in 58 adults studies. Only nine studies reported sensitivity and specificity, which varied substantially from 43% to 100%, and from 45% to 100%, respectively. Studies in adults have focused on the investigation of IL-6, TNF-α and hsCRP. There was no specific biomarker that was tested by a majority of authors in pediatric studies, and combinatorial urine biomarker approaches have shown preliminary promising results. In adults IL-6 and IL-10 seem to have a favorable potential to become a good biomarker to identify OSA.

Sleep apnea-hypopnea syndrome and type 2 diabetes. A reciprocal relationship?

Epidemiological data suggest that sleep apnea-hypopnea syndrome (SAHS) is independently associated with the development of insulin resistance and glucose intolerance. Moreover, despite significant methodological limitations, some studies report a high prevalence of SAHS in patients with type 2 diabetes mellitus (DM2). A recent meta-analysis shows that moderate-severe SAHS is associated with an increased risk of DM2 (relative risk=1.63 [1.09 to 2.45]), compared to the absence of apneas and hypopneas. Common alterations in various pathogenic pathways add biological plausibility to this relationship. Intermittent hypoxia and sleep fragmentation, caused by successive apnea-hypopnea episodes, induce several intermediate disorders, such as activation of the sympathetic nervous system, oxidative stress, systemic inflammation, alterations in appetite-regulating hormones and activation of the hypothalamic-pituitary-adrenal axis which, in turn, favor the development of insulin resistance, its progression to glucose intolerance and, ultimately, to DM2. Concomitant SAHS seems to increase DM2 severity, since it worsens glycemic control and enhances the effects of atherosclerosis on the development of macrovascular complications. Furthermore, SAHS may be associated with the development of microvascular complications: retinopathy, nephropathy or diabetic neuropathy in particular. Data are still scant, but it seems that DM2 may also worsen SAHS progression, by increasing the collapsibility of the upper airway and the development of central apneas and hypopneas.

Vaspin and lipocalin-2 levels in severe obsructive sleep apnea

BACKGROUND

Vaspin and lipocalin-2 are less-known recent members of adipocytokine family. There are ongoing studies investigating the role of vaspin ve lipocalin-2 in metabolic syndrome (MS). Obstructive sleep apnea syndrome (OSAS) is independently associated with an increased prevalence of MS. We aimed to measure the levels of vaspin and lipocalin-2 which are secreted from adipocytes in patients with severe OSAS and examine the relationship between these two adipocytokines and OSAS.

METHODS

THE STUDY CONSISTED OF TWO GROUPS: severe OSAS patients with an apnea-hypopnea index (AHI) of >30/h (OSAS group, 34 subjects) and age-matched healthy volunteers with a AHI <5/h (control group, 25 subjects) Serum levels of vaspin and lipocalin-2 in these two groups were compared.

RESULTS

Serum levels of vaspin were significantly lower in OSAS group; patients with severe OSAS compared with control group; healthy volunteers (OSAS group: 0.69±0.5 vs. control group: 1.24±1.13; P=0.034). The difference between the two groups in terms of serum levels of lipocalin-2 has not reached statistical significance (OSAS group: 61.6±18.2 vs. control group: 68.5±20.1; P=0.17).

CONCLUSIONS

We found that serum vaspin levels were significantly lower in patients with severe OSAS compared with healthy controls. Lipocalin-2 levels were similar. The decrease in serum vaspin levels in severe OSAS patients may be important in diagnosis and follow-up of these patients.

Obstructive sleep apnoea and diabetes: an update

PURPOSE OF REVIEW

The relationship between obstructive sleep apnoea (OSA) and dysglycaemia is well established. However, uncertainty remains as to the extent that obesity mediates this relationship. The impact of OSA treatment on glucose metabolism and the consequences of having OSA in patients with diabetes is unclear. This review aims to summarize the latest evidence regarding the links between OSA and dysglycaemia.

RECENT FINDINGS

OSA is associated with insulin resistance in lean individuals and predicts insulin resistance worsening longitudinally. Continuous positive airway pressure (CPAP) lowers insulin resistance in CPAP-compliant patients. OSA is associated with impaired β-cell function. In patients with type 2 diabetes (T2D), the association between OSA and glycosylated haemoglobin (HbA1c) is related to nocturnal hypoxaemia. Apnoea hypopnoea index (AHI) during rapid eye movement (REM) (not non-REM) sleep is associated with HbA1c. In-laboratory, supervised CPAP improves glycaemia. OSA is associated with and predicts the progression of some diabetic vascular complications. Intensive lifestyle intervention in patients with T2D improves OSA independent of weight loss.

SUMMARY

OSA is associated with insulin resistance and β-cell dysfunction independent of obesity. OSA is associated with HbA1c and vascular complications in patients with T2D. CPAP might improve insulin resistance and glycaemic measures. Lifestyle intervention has a significant impact on AHI in patients with T2D.

Study of leptin and adiponectin as disease markers in subjects with obstructive sleep apnea

Background. Published studies showed conflicting results of the associations between adiponectin and leptin levels and obstructive sleep apnoea (OSA). In obese patients, plasma leptin is elevated and adiponectin is decreased, and we postulate that these adipokines could be potential markers of clinical and metabolic perturbations in patients with OSA. Methods. 147 patients with suspected OSA had polysomnography to determine the Respiratory Disturbance Index (RDI). We measured fasting plasma glucose (FPG), fasting serum insulin, plasma leptin, adiponectin, and full lipid profile. Patients were classified on the basis of the RDI, degree of adiposity, and insulin resistance (IR) (homeostasis model assessment of insulin resistance (HOMAIR)). Results. 28.6% of subjects had normal polysomnography, 34.8% had mild OSA, 19.6% had moderate OSA, and 17% had severe OSA. Obesity was more prevalent in subjects with moderate-severe OSA (47%). Adiponectin decreased significantly (P = 0.041) with increasing severity of OSA. Though BMI was significantly higher in subjects with severe OSA, paradoxically, leptin was lowest in those subjects independent of gender dimorphism. Conclusions. Adiponectin is an independent marker of disease severity in patients with OSA. The paradoxical decrease in circulating leptin, which suggests impaired secretion, deserves further studies as a potential marker of severe OSA.

Treating obstructive sleep apnea with continuous positive airway pressure benefits type 2 diabetes management

Type 2 diabetes mellitus (T2DM) and obstructive sleep apnea (OSA) are both common major public health concerns. Epidemiological and clinical evidence postulates that OSA may be a causal factor in the pathogenesis of T2DM. This review examines recent empirical developments in theory, research, and practice regarding T2DM and OSA. We first examined the data from 10 studies that covered 281 patients with T2DM who used continuous positive airway pressure therapy, followed by research that describes how hypoxia/reoxygenation in OSA may be key triggers that initiate or contribute to the status of insulin resistance and inflammation. We then propose mechanisms that may relate diabetes with OSA. The issues that should be addressed in the future are outlined. We suggest that intervention with continuous positive airway pressure may improve diabetic symptoms and should be encouraged for patients with diabetes.

Impact of OSA on biological markers in morbid obesity and metabolic syndrome

BACKGROUND AND OBJECTIVE

There is compelling evidence that obstructive sleep apnoea (OSA) can affect metabolic syndrome (MetS) and cardiovascular risk, but the intermediate mechanisms through which it occurs have not been well defined. We explored the impact of OSA in morbidly obese patients with MetS on adipokines, pro-inflammatory markers, endothelial dysfunction, and atherosclerosis markers.

METHODS

We included 52 morbidly obese patients in an observational study matched for age, gender and central obesity in 3 groups (OSA-MetS, Non-OSA-MetS, and Non OSA-non-MetS). Anthropometrical, blood pressure, and fasting blood measurements were obtained the morning after an overnight polysomnography. VEGF, soluble CD40 ligand (sCD40L), TNF-α, IL-6, leptin, adiponectin, and chemerin were determined in serum by ELISA. OSA was defined as apnea/ hypopnea index ≥ 15 and MetS by NCEP-ATP III.

RESULTS

Cases and control subjects did not differ in age, BMI, waist circumference, and gender (43 ± 10 years, 46 ± 5 kg/m(2), 128 ± 10 cm, 71% females). The cases had severe OSA with 47 (32-66) events/h, time spent < 90% SpO2 7% (5%-31%). All groups presented similar serum cytokines, adipokines, VEGF, and sCD40L levels.

CONCLUSIONS

In a morbidly obese population with established MetS, the presence of OSA did not determine any differences in the studied mediators when matched by central obesity. Morbidly obese NonOSA-NonMetS had a similar inflammatory, adipokine VEGF, and sCD40L profile as those with established MetS, with or without OSA. Obesity itself could overwhelm the effect of sleep apnea and MetS in the studied biomarkers.

CITATION

Salord N; Gasa M; Mayos M; Fortuna-Gutierrez AM; Montserrat JM; Sánchez-de-la-Torre M; Barceló A; Barbé F; Vilarrasa N; Monasterio C. Impact of OSA on biological markers in morbid obesity and metabolic syndrome.

Obstructive Sleep Apnoea and Type 2 Diabetes

With the growing prevalence of obesity, the burden of type 2 diabetes is increasing. Obstructive sleep apnoea (OSA) is a very common medical condition that is associated with increased risk of cardiovascular disease and mortality. Obesity is a common risk factor for OSA and type 2 diabetes and hence it is not surprising that OSA and type 2 diabetes are interlinked. OSA has been shown to be an independent risk factor for the development of incident pre-diabetes/type 2 diabetes. OSA is also associated with worse glycaemic control and vascular disease in patients with type 2 diabetes. However, evidence for the benefits of OSA treatment in patients with type 2 diabetes is still lacking. The aim of this article is to provide an overview of OSA, the relationships between OSA and dysglycaemia and the impact of OSA in patients with type 2 diabetes, highlighting recent advances in the field.

Serum omentin levels in patients with obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is associated with increased rates of cardiovascular diseases (CVD). The basic mechanisms involved in the increased cardiovascular risk of OSAS remain unclear. Recent discoveries of fat-secreted substances which serve endocrine roles improve our understanding of the relationship between OSAS, CVD, and the metabolic syndrome. In this study, we aimed to examine associations between omentin levels and OSA.

METHODS

Forty-six newly diagnosed OSA patients and 35 non-apneic controls were enrolled in this study. Demographical data, cigarette smoking status, previous history of chronic diseases including CVD and metabolic diseases and drugs, and habits were obtained using a standardized questionnaire. All patients underwent polysomnographic evaluation. Omentin was measured the following morning.

RESULTS

The mean age was 48.1 ± 12.5 (24-74) years in the OSA group and 42.8 ± 14.1 (21-69) years in the control group. Of the 81 patients, 46 (34 males and 12 females) were classified as having OSA and 35 patients (20 males and 15 females) as control. Plasma levels of omentin were found to be markedly higher in OSA patients (570.8 ng/ml) than in the control group (432.0 ng/ml; p < 0.001). In addition, plasma levels of omentin were found to be high in all OSA subgroups than in controls. The plasma omentin levels were significantly correlated only with age in patients with OSA.

CONCLUSIONS

We conclude that circulating omentin levels are elevated in OSA patients. To the best of our knowledge, this is the first clinical study that demonstrated the association between omentin and OSA.

Pathophysiologic mechanisms of cardiovascular disease in obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is a highly prevalent sleep disorder, characterized by repeated disruptions of breathing during sleep. This disease has many potential consequences including excessive daytime sleepiness, neurocognitive deterioration, endocrinologic and metabolic effects, and decreased quality of life. Patients with OSAS experience repetitive episodes of hypoxia and reoxygenation during transient cessation of breathing that provoke systemic effects. Furthermore, there may be increased levels of biomarkers linked to endocrine-metabolic and cardiovascular alterations. Epidemiological studies have identified OSAS as an independent comorbid factor in cardiovascular and cerebrovascular diseases, and physiopathological links may exist with onset and progression of heart failure. In addition, OSAS is associated with other disorders and comorbidities which worsen cardiovascular consequences, such as obesity, diabetes, and metabolic syndrome. Metabolic syndrome is an emerging public health problem that represents a constellation of cardiovascular risk factors. Both OSAS and metabolic syndrome may exert negative synergistic effects on the cardiovascular system through multiple mechanisms (e.g., hypoxemia, sleep disruption, activation of the sympathetic nervous system, and inflammatory activation). It has been found that CPAP therapy for OSAS provides an objective improvement in symptoms and cardiac function, decreases cardiovascular risk, improves insulin sensitivity, and normalises biomarkers. OSAS contributes to the pathogenesis of cardiovascular disease independently and by interaction with comorbidities. The present review focuses on indirect and direct evidence regarding mechanisms implicated in cardiovascular disease among OSAS patients.

Consequences of obstructive sleep apnea on metabolic profile: a Population-Based Survey

OBJECTIVE

Epidemiologic studies that control for potential confounders are needed to assess the independent associations of obstructive sleep apnea (OSA) with metabolic abnormalities. The aim of our study was to evaluate the associations of OSA with metabolic abnormalities among the adult population of Sao Paulo, Brazil.

DESIGN AND METHODS

Questionnaires were applied face-to-face, full night polysomnography (PSG) was performed, and blood samples were collected in a population-based survey in Sao Paulo, Brazil, adopting a probabilistic three-stage cluster sample method. The metabolic profile included fasting glucose, insulin, and lipid levels. The hepatic insulin resistance index was assessed by the homeostasis model assessment-estimated insulin resistance (HOMAIR ).

RESULTS

A total of 1,042 volunteers underwent PSG. Mild OSA and moderate to severe OSA comprised 21.2% and 16.7% of the population, respectively. Subjects with severe to moderate OSA were older, more obese, had higher fasting glucose, HOMAIR , and triglycerides (TG) levels than did the mild and non-OSA group (P < 0.001). Multivariate regression analyses showed that an apnea-hypopnea index (AHI) ≥ 15 and a time of oxy-hemoglobin saturation <90% were independently associated with impaired fasting glucose, elevated TG, and HOMAIR .

CONCLUSIONS

The results of this large cross-sectional epidemiological study showed that the associations of OSA and metabolic abnormalities were independent of other risk factors.

Neck circumference, metabolic syndrome and obstructive sleep apnea syndrome; evaluation of possible linkage

Background

This study was performed to evaluate neck circumference (NC) and metabolic syndrome (MS) parameters in severe and non-severe (mild-moderate) obstructive sleep apnea syndrome (OSAS) patients according to apnea-hypopnea index (AHI).

Material/Method

We enrolled 44 patients diagnosed with OSAS based on overnight polysomnography. The diagnosis of OSAS was based on AHI. Apnea is a pause of airflow for more than 10 seconds. and hypopnea is a decrease of airflow for more than 10 seconds and oxygen desaturation of 4% or greater. AHI score. per hour; below 5 normal. 5–29 mild-moderate. 30 and above were grouped as severe OSAS. Height. weight. neck circumference (NC). waist circumference (WC) and body mass index (BMI) of the patients were measured. MS was diagnosed by the Adult Treatment Panel (ATP) III criteria (≥3 of the following abnormalities): 1) WC ≥94 cm for males, ≥80 cm for females; 2) arterial blood pressure ≥130/85 mmHg; 3) fasting blood glucose ≥100 mg/dl; 4) high density lipoprotein (HDL) cholesterol <40 mg/dl in man, <50 mg/dl in women; 5) triglycerides ≥150 mg/dl.

Results

Mean BMI and NC were higher in severe OSAS patients compared to non-severe patients (p=0.021. p<0.001). According to ATP III criteria. 64% of severe and 61.1% of non-severe OSAS patients were MS (p=0.847). A logistic regression model displayed an association with NC as a risk factor for severe OSAS (p=0.01). but not with MS.

Conclusions

In this study. NC in severe OSAS patients was significantly higher than in non-severe OSAS patients. The prevalence of metabolic syndrome was not correlated with OSAS severity. NC is an independent risk factor for severe OSAS.

Death by a thousand cuts in Alzheimer's disease: hypoxia--the prodrome

A wide range of clinical consequences may be associated with obstructive sleep apnea (OSA) including systemic hypertension, cardiovascular disease, pulmonary hypertension, congestive heart failure, cerebrovascular disease, glucose intolerance, impotence, gastroesophageal reflux, and obesity, to name a few. Despite this, 82 % of men and 93 % of women with OSA remain undiagnosed. OSA affects many body systems, and induces major alterations in metabolic, autonomic, and cerebral functions. Typically, OSA is characterized by recurrent chronic intermittent hypoxia (CIH), hypercapnia, hypoventilation, sleep fragmentation, peripheral and central inflammation, cerebral hypoperfusion, and cerebral glucose hypometabolism. Upregulation of oxidative stress in OSA plays an important pathogenic role in the milieu of hypoxia-induced cerebral and cardiovascular dysfunctions. Strong evidence underscores that cerebral amyloidogenesis and tau phosphorylation--two cardinal features of Alzheimer's disease (AD), are triggered by hypoxia. Mice subjected to hypoxic conditions unambiguously demonstrated upregulation in cerebral amyloid plaque formation and tau phosphorylation, as well as memory deficit. Hypoxia triggers neuronal degeneration and axonal dysfunction in both cortex and brainstem. Consequently, neurocognitive impairment in apneic/hypoxic patients is attributable to a complex interplay between CIH and stimulation of several pathological trajectories. The framework presented here helps delineate the emergence and progression of cognitive decline, and may yield insight into AD neuropathogenesis. The global impact of CIH should provide a strong rationale for treating OSA and snoring clinically, in order to ameliorate neurocognitive impairment in aged/AD patients.

Medical disorders impacted by obstructive sleep apnea

Normal-sleeping individuals experience a lower metabolic rate and relative cardiovascular quiescent state with lower heart rate and blood pressure that naturally occurs during sleep compared with the waking state. In patients with obstructive sleep apnea (OSA), this quiescent state becomes disrupted. Research has shown a higher risk for several medical disorders, most ominous being a myocardial infarction or stroke. This article serves as an overview to the cardiovascular, cerebrovascular, metabolic, and gastroesophageal effects of OSA.

OSA and atherosclerosis

Untreated obstructive sleep apnea (OSA) is increasingly recognized as a risk factor contributing to cardiovascular morbidity and mortality. Research in recent decades has uncovered many components of the complex pathological events leading to the atherosclerotic vascular diseases in OSA, which involve heightened oxidative stress as a result of intermittent hypoxia, vascular inflammation, activation of platelet and coagulation cascades, endothelial dysfunction and ultimately the formation of atherosclerotic plagues. The close association of OSA and conventional cardiovascular risk factors including hypertension, diabetes mellitus, dyslipidemia and obesity adds to the adverse cardiovascular sequelae. Further studies are required to clarify further on the pathophysiological processes, and the effect size of OSA therapy, and other potential preventive strategies.

Obesity, obstructive sleep apnoea and metabolic syndrome

OSA is increasingly recognized as a major health problem in developed countries. Obesity is the most common risk factor in OSA and hence, the prevalence of OSA is undoubtedly rising given the epidemic of obesity. Recent data also suggest that OSA is highly associated with the metabolic syndrome, and it is postulated that OSA contributes to cardiometabolic dysfunction, and subsequently vasculopathy. Current evidence regarding the magnitude of impact on ultimate cardiovascular morbidity or mortality attributable to OSA-induced metabolic dysregulation is scarce. Given the known pathophysiological triggers of intermittent hypoxia and sleep fragmentation in OSA, the potential mechanisms of OSA-obesity-metabolic syndrome interaction involve sympathetic activation, oxidative stress, inflammation and neurohumoral changes. There is accumulating evidence from human and animal/cell models of intermittent hypoxia to map out these mechanistic pathways. In spite of support for an independent role of OSA in the contribution towards metabolic dysfunction, a healthy diet and appropriate lifestyle modifications towards better control of metabolic function are equally important as CPAP treatment in the holistic management of OSA.

The relation of serum 25-hydroxyvitamin-D levels with severity of obstructive sleep apnea and glucose metabolism abnormalities

Obstructive sleep apnea (OSA) and 25-hydroxyvitamin-D₃ (25-OH-D) deficiency are two separate disorders associating with obesity, inflammation, and impaired glucose metabolism. We aimed to investigate the vitamin D status of OSA patients regarding to potential links between lower vitamin D levels and abnormal glucose metabolism, which is one of the main adverse outcomes of OSA. Study group is composed of 190 non-diabetic subjects who were suspected of having OSA. Subjects undergone polysomnography and were grouped due to apnea-hypopnea indices (AHI) as controls (AHI < 5, n = 47), mild OSA (5 ≤ AHI < 15, n = 46), moderate OSA (15 ≤ AHI < 30, n = 47), and severe OSA (AHI ≥ 30, n = 50). Serum 25-OH-D, HbA₁c, insulin levels were measured and 75-g oral glucose tolerance test was performed. Serum 25-OH-D level (ng/ml) of OSA patients were lower than control subjects (17.4 ± 6.9 vs. 19.9 ± 7.8), and decrement was parallel to severity of OSA; as 18.2 ± 6.4 (5 ≤ AHI < 15), 17.5 ± 7.4 (15 ≤ AHI < 30), and 16.3 ± 6.9 (AHI > 30), respectively (P = 0.097, r = -0.13). However, severe female OSA patients had significantly lower 25-OH-D levels (11.55 ng/ml), while control males had the highest mean value (21.7 ng/ml) (P < 0.001). Frequency of insulin resistance (IR) was 48%, prediabetes 41%, diabetes 16% in OSA patients. Mean 25-OH-D level of insulin resistant subjects (HOMA-IR ≥ 2.7, n = 77, AHI = 35.5) was lower than non-insulin resistant subjects (HOMA-IR < 2.7, n = 113, AHI = 19.8) as 16.18 ± 7.81 versus 19.2 ± 6.6, respectively (P = 0.004). 25-OH-D level of 91 non-diabetic subjects (n = 91, AHI = 19.7) was 19.5 ± 7.4, prediabetics (n = 75, AHI = 28.7) was 17.45 ± 6.9, and diabetics (n = 24, AHI = 46.3) was 13.8 ± 5.3 (P = 0.02). We showed that subjects with more severe OSA indices (AHI ≥ 15) tended to present lower vitamin D levels correlated to increased prevalence of IR, prediabetes, and diabetes. Vitamin D deficiency may play a role and/or worsen OSA's adverse outcomes on glucose metabolism. OSA patients may be considered for supplementation treatment which was shown to ameliorate abnormal glucose metabolism and inflammation.

Insulin resistance and adipose-derived hormones in young men with untreated obstructive sleep apnea

PURPOSE

Obstructive sleep apnea (OSA) increases the risk for insulin resistance (IR). The mechanisms that link the two are not clear and are frequently confounded by obesity. OSA is associated with alterations in adipose-derived hormones (adipokines) that increase IR; however, previous studies have focused on middle-aged and older adults. The objective of this study was to determine if IR and alterations in adipokines exist in young men with OSA, independent of obesity.

METHODS

Subjects were assigned into the following groups based on body mass index and presence of OSA: obese with OSA (OSA, n = 12), obese without OSA (NOSA, n = 18), and normal weight without OSA (CON, n = 15). Fasting blood was obtained for batch analysis of biomarkers of IR. The homeostasis model assessment (HOMA) method was used to assess IR.

RESULTS

HOMA and leptin were higher in the OSA group than the CON group. There were no differences in insulin, tumor necrosis factor alpha (TNF-α), and interleukin-6 (IL-6) between the OSA and NOSA groups. Adiponectin was lower in the OSA group vs. NOSA and CON; however, when controlled for central abdominal fat (CAF), the difference was nullified. When controlled for total body adiposity, however, CAF was 24 % higher in the subjects with OSA vs. subjects without OSA.

CONCLUSIONS

These findings suggest that excess CAF in young men with OSA may contribute to risk for type 2 diabetes indirectly by a degree that would otherwise not be reached through obesity, although further research is needed.

Plasma dehydroepiandrosterone sulphate and insulin-like growth factor I levels in obstructive sleep apnoea syndrome

CONTEXT

We aimed to assess whether obstructive sleep apnoea syndrome (OSAS) affects plasma IGF-1 and dehydroepiandrosterone sulphate (DHEA-S) levels in men, factors implicated in the development of age-related metabolic disorders.

DESIGN

We conducted a cross-sectional and longitudinal clinical study.

PATIENTS AND SETTING

We measured plasma IGF-1 and DHEA-S levels in 191 non-drug-treated Japanese men (34 primary snorers (PS), 88 patients with mild-to-moderate OSAS and 69 patients severe OSAS ).

RESULTS

Plasma IGF-1 and DHEA-S were negatively correlated with age. Plasma IGF-1 was also negatively correlated with plasma glucose, HOMA-IR and systolic blood pressure and apnoea parameters such as the apnoea-hypopnea index, minimum oxygen saturation and slow-wave sleep (SWS) time. Plasma DHEA-S was associated with plasma glucose, HbA1c and free fatty acid and was negatively correlated with SWS time. To eliminate the influence of age, PS, patients with mild-to-moderate OSAS and severe OSAS were divided into three groups by age: young (<40 years), middle-aged (40-59 years) and elderly (≥ 60 years). Patients with severe OSAS aged <40 or <60 years had lower plasma IGF-1 or DHEA-S levels, respectively, than did the corresponding snorers and mild-to-moderate OSAS groups. Continuous positive airway pressure therapy for generally 16-18 months increased plasma IGF-1 levels in patients with severe OSAS aged <40 years (n = 18). Plasma DHEA-S levels were increased in patients with severe OSAS aged <60 years, whose DHEA-S level was below the mean value for that age (n = 23/41).

CONCLUSION

Severe OSAS could reduce plasma IGF-1 and DHEA-S levels in younger, but not elderly Japanese men, which is potentially associated with the development of metabolic abnormalities.

Snoring, inflammatory markers, adipokines and metabolic syndrome in apparently healthy Chinese

OBJECTIVE

Chronic low-grade inflammation and adipokines dysregulation are linked to mechanisms underscoring the pathogenesis of obesity-related metabolic disorders. Little is known about roles of these cytokines on the association between snoring and metabolic syndrome (MetS). We aimed to investigate whether a cluster of cytokines are related to snoring frequency and its association with MetS in apparently healthy Chinese.

METHODS

Current analyses used a population-based sample including 1059 Shanghai residents aged 35-54 years. Self-reported snoring frequency was classified as never, occasionally and regularly. Fasting plasma glucose, lipid profile, insulin, C-reactive protein, interleukin-6, interleukin-18, lipopolysaccharide binding protein, high-molecular-weight adiponectin and leptin were measured. MetS was defined by the updated National Cholesterol Education Program Adult Treatment Panel III criteria for Asian-Americans.

RESULTS

Overweight/obese subjects had significantly higher prevalence of regular snorers than their normal-weight counterparts (34.8% vs. 11.5%, P<0.001). Regular snoring was associated with unfavorable profile of inflammatory markers and adipokines. However, those associations were abolished after adjustment for body mass index (BMI) or waist circumference. The MetS risk (multivariate-adjusted odds ratio 5.41, 95% confidence interval 3.72-7.88) was substantially higher in regular snorers compared with non-snorers. Controlling for BMI remarkably attenuated the association (2.03, 1.26-3.26), while adjusting for inflammatory markers and adipokines showed little effects.

CONCLUSION

Frequent snoring was associated with an elevated MetS risk independent of lifestyle factors, adiposity, inflammatory markers and adipokines in apparently healthy Chinese. Whether snoring pattern is an economic and no-invasive indicator for screening high-risk persons needs to be addressed prospectively.

Hypertension in obesity

Obesity and HTN are on the rise in the world. HTN seems to be the most common obesity-related health problem and visceral obesity seems to be the major culprit. Unfortunately, only 31% of hypertensives are treated to goal. This translates into an increased incidence of CVD and related morbidity and mortality. Several mechanisms have been postulated as the causes of obesity-related HTN. Activation of the RAAS, SNS, insulin resistance, leptin, adiponectin, dysfunctional fat, FFA, resistin, 11 Beta dehydrogenase, renal structural and hemodynamic changes, and OSA are some of the abnormalities in obesity-related HTN. Many of these factors are interrelated. Treatment of obesity should begin with weight loss via lifestyle modifications, medications, or bariatric surgery. According to the mechanisms of obesity-related HTN, it seems that drugs that blockade the RAAS and target the SNS should be ideal for treatment. There is not much evidence in the literature that one drug is better than another in controlling obesity-related HTN. There have only been a few studies specifically targeting the obese hypertensive patient, but recent trials that emphasize the importance of BP control have enrolled both overweight and obese subjects. Until we have further studies with more in-depth information about the mechanisms of obesity-related HTN and what the targeted treatment should be, the most important factor necessary to control the obesity-related HTN pandemic and its CVD and CKD consequences is to prevent and treat obesity and to treat HTN to goal.

Effects of sleep apnea on nocturnal free fatty acids in subjects with heart failure

STUDY OBJECTIVES

Sleep apnea is common in patients with congestive heart failure, and may contribute to the progression of underlying heart disease. Cardiovascular and metabolic complications of sleep apnea have been attributed to intermittent hypoxia. Elevated free fatty acids (FFA) are also associated with the progression of metabolic, vascular, and cardiac dysfunction. The objective of this study was to determine the effect of intermittent hypoxia on FFA levels during sleep in patients with heart failure.

DESIGN AND INTERVENTIONS

During sleep, frequent blood samples were examined for FFA in patients with stable heart failure (ejection fraction < 40%). In patients with severe sleep apnea (apnea-hypopnea index = 65.5 ± 9.1 events/h; average low SpO₂ = 88.9%), FFA levels were compared to controls with milder sleep apnea (apnea-hypopnea index = 15.4 ± 3.7 events/h; average low SpO₂ = 93.6%). In patients with severe sleep apnea, supplemental oxygen at 2-4 liters/min was administered on a subsequent night to eliminate hypoxemia.

MEASUREMENTS AND RESULTS

Prior to sleep onset, controls and patients with severe apnea exhibited a similar FFA level. After sleep onset, patients with severe sleep apnea exhibited a marked and rapid increase in FFA relative to control subjects. This increase persisted throughout NREM and REM sleep exceeding serum FFA levels in control subjects by 0.134 mmol/L (P = 0.0038). Supplemental oxygen normalized the FFA profile without affecting sleep architecture or respiratory arousal frequency.

CONCLUSION

In patients with heart failure, severe sleep apnea causes surges in nocturnal FFA that may contribute to the accelerated progression of underlying heart disease. Supplemental oxygen prevents the FFA elevation.