Effects of continuous positive airway pressure on glycemic control and insulin resistance in patients with obstructive sleep apnea: a meta-analysis

Characteristics of obstructive sleep apnea related to insulin resistance

BACKGROUND

Obstructive sleep apnea (OSA) is associated with multiple comorbidities, including diabetes. Its development is preceded by alterations in the initial phase of carbohydrate metabolism characterized by insulin resistance. This study aims to evaluate the role of intermittent hypoxia and sleep fragmentation characteristic of OSA on the risk of insulin resistance among apneic patients without diabetes.

METHODOLOGY

92 consecutive patients with OSA without evidence of diabetes were recruited. Overnight video polysomnography was performed and, the following morning, fasting blood glucose, insulin and glycosylated hemoglobin were determined. Insulin resistance was measured using the HOMA-IR index.

RESULTS

Insulin resistance was present in 52.2% of OSA patients. In these subjects, insulin resistance was independently associated to the apnea index during REM sleep (adjusted odds ratio [aOR] 1.09; 95% CI, 1.03 to 1.16; p = 0.004), desaturation index (aOR 1.08; 95% CI: 1.04 to 1.13; p = 0.027), and sleep time with oxygen saturation below 90% (aOR 1.04; 95% CI 1.00 to 1.08; p = 0.049). Furthermore, the HOMA-IR level was also directly related to the desaturation index (standardized regression coefficient [B] = 0.514, p < 0.001) and to the apnea index during REM sleep (B = 0.344, p = 0.002).

CONCLUSIONS

Intermittent hypoxia and disturbances in REM sleep emerge as main contributors to insulin resistance in OSA patients yet to experience diabetes onset.

The benefits of hypoglycemic therapy for patients with obstructive sleep apnea

PURPOSE

Obstructive sleep apnea (OSA) is often associated with glycemic abnormalities. This study is conducted to investigate the effects of hypoglycemic therapy on OSA-related indicators.

METHOD

We systematically searched Web of Science, PubMed, Embase, and the Cochrane Library for articles on OSA patients receiving any hypoglycemic drugs, published until December 25, 2022. Seven original studies were finally included. The proposal was registered with PROSPERO (CRD42022351206).

RESULTS

In summary, in addition to reduced glycosylated hemoglobin A1c (HbA1c), we found that hypoglycemic treatment can lower the apnea-hypopnea index (AHI) by 7.07/h (p = 0.0001). Although long-term treatment (> 12 weeks) achieved a more significant reduction in HbA1c (- 1.57% vs. - 0.30%) compared to short-term treatment (≤ 12 weeks), there was no significant difference between the two in terms of AHI (intergroup p-value = 0.27). We also found that patients using sodium glucose cotransporter 2 inhibitors (SGLT2i) experienced a greater reduction in AHI (- 11.00/h, p < 0.00001). Additionally, hypoglycemic treatment also showed certain improvements in related indicators like Epworth Sleepiness Scale, body mass index, and blood pressure.

CONCLUSIONS

Our results affirm the benefits of hypoglycemic treatment for OSA patients and highlight the notable effect of SGLT2i. Further researches are needed to help doctors gain a comprehensive understanding of the interaction between OSA and glycemic abnormalities.

Effect of Continuous Positive Airway Pressure on Glucose and Lipid Profiles in Patients With Obstructive Sleep Apnoea: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND AND AIM

Continuous Positive Airway Pressure (CPAP) is the most effective therapy for symptomatic obstructive sleep apnoea (OSA). However, uncertainty remains about the effectiveness of CPAP in improving OSA-related metabolic dysregulation. This meta-analysis of randomized controlled trials (RCTs) aimed to investigate whether CPAP, compared to other control treatments, could improve glucose or lipid metabolism in OSA patients.

METHODS

Relevant articles were searched in three different databases (MEDLINE, EMBASE and Web of Science) from inception to 6th Feb 2022 through specific search terms and selection criteria.

RESULTS

From a total of 5553 articles, 31 RCTs were included. CPAP modestly improved insulin sensitivity as determined by mean fasting plasma insulin and Homeostasis Model Assessment of Insulin Resistance reduction of 1.33mU/L and 0.287, respectively. In subgroup analyses pre-diabetic/type 2 diabetic patients as well as those with sleepy OSA showed a greater response to CPAP. Regarding lipid metabolism, CPAP was associated with a mean total cholesterol reduction of 0.064mmol/L. In subgroup analyses, the benefit was higher in patients that showed more severe OSA and oxygen desaturations at the baseline sleep study as well as in younger and obese subjects. Neither glycated haemoglobin nor triglycerides, HDL- and LDL-cholesterol were reduced by CPAP.

CONCLUSION

CPAP treatment may improve insulin sensitivity and total cholesterol levels in OSA patients but with low effect size. Our results suggest that CPAP does not substantially improve metabolic derangements in an unselected OSA population, but the effect may be higher in specific subgroups of OSA patients.

Personalized Medicine and Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a common disease that is often under-diagnosed and under-treated in all ages. This is due to differences in morphology, diversity in clinical phenotypes, and differences in diagnosis and treatment of OSA in children and adults, even among individuals of the same age. Therefore, a personalized medicine approach to diagnosis and treatment of OSA is necessary for physicians in clinical practice. In children and adults without serious underlying medical conditions, polysomnography at sleep labs may be an inappropriate and inconvenient testing modality compared to home sleep apnea testing. In addition, the apnea-hypopnea index should not be considered as a single parameter for making treatment decisions. Thus, the treatment of OSA should be personalized and based on individual tolerance to sleep-quality-related parameters measured by the microarousal index, harmful effects of OSA on the cardiovascular system related to severe hypoxia, and patients' comorbidities. The current treatment options for OSA include lifestyle modification, continuous positive airway pressure (CPAP) therapy, oral appliance, surgery, and other alternative treatments. CPAP therapy has been recommended as a cornerstone treatment for moderate-to-severe OSA in adults. However, not all patients can afford or tolerate CPAP therapy. This narrative review seeks to describe the current concepts and relevant approaches towards personalized management of patients with OSA, according to pathophysiology, cluster analysis of clinical characteristics, adequate combined therapy, and the consideration of patients' expectations.

Type 2 diabetes

Type 2 diabetes accounts for nearly 90% of the approximately 537 million cases of diabetes worldwide. The number affected is increasing rapidly with alarming trends in children and young adults (up to age 40 years). Early detection and proactive management are crucial for prevention and mitigation of microvascular and macrovascular complications and mortality burden. Access to novel therapies improves person-centred outcomes beyond glycaemic control. Precision medicine, including multiomics and pharmacogenomics, hold promise to enhance understanding of disease heterogeneity, leading to targeted therapies. Technology might improve outcomes, but its potential is yet to be realised. Despite advances, substantial barriers to changing the course of the epidemic remain. This Seminar offers a clinically focused review of the recent developments in type 2 diabetes care including controversies and future directions.

Obstructive sleep apnea screening, diagnosis, and treatment in the transportation industry

Obstructive sleep apnea (OSA) is a common, identifiable, and treatable disorder with serious health, safety, and financial implications-including sleepiness- related crashes and incidents-in workers who perform safety-sensitive functions in the transportation industry. Up to one-third of crashes of large trucks are attributable to sleepiness, and large truck crashes result in more than 4,000 deaths annually. For each occupant of a truck who is killed, 6 to 7 occupants of other vehicles are killed. Treatment of OSA is cost-effective, lowers crash rates, and improves health and well-being. A large body of scientific evidence and expert consensus supports the identification and treatment of OSA in transportation operators. An Advanced Notice of Proposed Rulemaking regarding the diagnosis and treatment of OSA in commercial truck and rail operators was issued by the Federal Motor Carrier Safety Administration and Federal Railroad Administration, but it was later withdrawn. This reversal of the agencies' position has caused confusion among some, who have questioned whether efforts to identify and treat the disorder are warranted. In response, we urge key stakeholders, including employers, operators, legislators, payers, clinicians, and patients, to engage in a collaborative, patient-centered approach to address the disorder. At a minimum, stakeholders should follow the guidelines issued by a medical review board commissioned by the Federal Motor Carrier Safety Administration in 2016 alone, or in combination with the 2006 criteria, "Sleep Apnea and Commercial Motor Vehicle Operators," a Statement from the Joint Task Force of the American College of Chest Physicians, the American College of Occupational and Environmental Medicine, and the National Sleep Foundation developed by a joint task force. As research in this area continues to evolve, waiting is no longer an option, and the current standard of care demands action to mitigate the burden of serious health and safety risks due to this common, treatable disorder.

CITATION

Das AM, Chang JL, Berneking M, Hartenbaum NP, Rosekind M, Gurubhagavatula I. Obstructive sleep apnea screening, diagnosis, and treatment in the transportation industry. J Clin Sleep Med. 2022;18(10):2471-2479.

The Clash of Two Epidemics: the Relationship Between Opioids and Glucose Metabolism

PURPOSE OF REVIEW

We are currently in the midst of a global opioid epidemic. Opioids affect many physiological processes, but one side effect that is not often taken into consideration is the opioid-induced alteration in blood glucose levels.

RECENT FINDINGS

This review shows that the vast majority of studies report that opioid stimulation increases blood glucose levels. In addition, plasma levels of the endogenous opioid β-endorphin rise in response to low blood glucose. In contrast, in hyperglycaemic baseline conditions such as in patients with type 2 diabetes mellitus (T2DM), opioid stimulation lowers blood glucose levels. Furthermore, obesity itself alters sensitivity to opioids, changes opioid receptor expression and increases plasma β-endorphin levels. Thus, opioid stimulation can have various side effects on glycaemia that should be taken into consideration upon prescribing opioid-based medication, and more research is needed to unravel the interaction between obesity, glycaemia and opioid use.

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.

Gender Differences in the Context of Obstructive Sleep Apnea and Metabolic Diseases

The relationship between obstructive sleep apnea (OSA) and endocrine and metabolic disease is unequivocal. OSA, which is characterized by intermittent hypoxia and sleep fragmentation, leads to and exacerbates obesity, metabolic syndrome, and type 2 diabetes (T2D) as well as endocrine disturbances, such as hypothyroidism and Cushing syndrome, among others. However, this relationship is bidirectional with endocrine and metabolic diseases being considered major risk factors for the development of OSA. For example, polycystic ovary syndrome (PCOS), one of the most common endocrine disorders in women of reproductive age, is significantly associated with OSA in adult patients. Several factors have been postulated to contribute to or be critical in the genesis of dysmetabolic states in OSA including the increase in sympathetic activation, the deregulation of the hypothalamus-pituitary axis, the generation of reactive oxygen species (ROS), insulin resistance, alteration in adipokines levels, and inflammation of the adipose tissue. However, probably the alterations in the hypothalamus-pituitary axis and the altered secretion of hormones from the peripheral endocrine glands could play a major role in the gender differences in the link between OSA-dysmetabolism. In fact, normal sleep is also different between men and women due to the physiologic differences between genders, with sex hormones such as progesterone, androgens, and estrogens, being also connected with breathing pathologies. Moreover, it is very well known that OSA is more prevalent among men than women, however the prevalence in women increases after menopause. At the same time, the step-rise in obesity and its comorbidities goes along with mounting evidence of clinically important sex and gender differences. Metabolic and cardiovascular diseases, seen as a men's illness for decades, presently are more common in women than in men and obesity has a higher association with insulin-resistance-related risk factors in women than in men. In this way, in the present manuscript, we will review the major findings on the overall mechanisms that connect OSA and dysmetabolism giving special attention to the specific regulation of this relationship in each gender. We will also detail the gender-specific effects of hormone replacement therapies on metabolic control and sleep apnea.

Long-Term Weight Change and Glycemic Control in Patients With Type 2 Diabetes Mellitus and Treated vs. Untreated Sleep-Disordered Breathing-Analysis From the DIAbetes COhoRtE

Hypothesis: Positive airway pressure (PAP) is the standard treatment for sleep-disordered breathing (SDB), a prevalent condition in patients with type 2 diabetes mellitus (DM2). Recent studies showed that short-term PAP treatment may cause weight gain. However, long-term data for patients with DM2 are scarce. Therefore, the aim of the present analysis was to assess changes in weight and glycemic control in patients with DM2 and treated vs. untreated SDB.

Methods: The DIAbetes COhoRtE (DIACORE) study is a prospective population-based cohort study in patients with DM2. At baseline, patients of the DIACORE-SDB sub-study were tested for SDB [defined as apnea-hypopnea-index (AHI) ≥ 15/h] using a two-channel ambulatory SDB-monitoring device. In this observational study, PAP treatment was initiated in a subgroup of patients with SDB (SDB PAP) within clinical routine between the baseline and first follow-up visit [median observation period of 2.3 (2.2; 2.4) years], whereas the other patients with SDB did not receive PAP (SDB untreated). At baseline and first follow-up visit, weight and HbA1c were assessed.

Results: Of the 346 patients with SDB [mean age 68 years, 71% male, body-mass index (BMI) 31.9 kg/m²], 17% were in the SDB PAP and 83% in the SDB untreated group. Weight change within the observation period was similar in both groups (−0.2 and −0.9 kg; p = 0.322). The percentage of patients with severe weight gain (≥ 5 kg) within the observation period was significantly higher in the SDB PAP group compared to the SDB untreated group (15.0 vs. 5.6%; p = 0.011). Multivariable regression analysis, accounting for baseline HbA1c, insulin substitution, BMI, waist-to-hip ratio (WHR), physical activity, and AHI, showed that PAP treatment was significantly associated with a weight gain ≥ 5 kg [odds ratio (OR) = 3.497; 95% CI (1.343; 9.106); p = 0.010] and an increase in HbA1c [B = 2.410; 95% CI (0.118; 4.702); p = 0.039].

Conclusion: Median weight change was similar in patients with SDB with and without PAP treatment. However, patients with DM2 and PAP treatment have an increased risk of severe long-term weight gain and an increase in HbA1c.

Clinical Trial registration: DRKS00010498

Positive airway pressure (PAP) treatment reduces glycated hemoglobin (HbA1c) levels in obstructive sleep apnea patients with concomitant weight loss: Longitudinal data from the ESADA

Patients with obstructive sleep apnea (OSA) are at increased risk of developing metabolic disease such as diabetes. The effects of positive airway pressure on glycemic control are contradictory. We therefore evaluated the change in glycated hemoglobin (HbA1c) in a large cohort of OSA patients after long-term treatment with positive airway pressure. HbA1c levels were assessed in a subsample of the European Sleep Apnea Database [n=1608] at baseline and at long-term follow up with positive airway pressure therapy (mean 378.9±423.0 days). In a regression analysis, treatment response was controlled for important confounders. Overall, HbA1c decreased from 5.98±1.01% to 5.93±0.98% (p=0.001). Patient subgroups with a more pronounced HbA1c response included patients with diabetes (-0.15±1.02, p=0.019), those with severe OSA baseline (-0.10±0.68, p=0.005), those with morbid obesity (-0.20±0.81, p<0.001). The strongest HbA1c reduction was observed in patients with a concomitant weight reduction >5 kilos (-0.38±0.99, p<0.001). In robust regression analysis, severe OSA (p=0.038) and morbid obesity (p=0.005) at baseline, and weight reduction >5 kilos (p<0.001) during follow up were independently associated with a reduction of HbA1c following PAP treatment. In contrast, PAP treatment alone without weight reduction was not associated with significant Hb1Ac reduction. In conclusion, positive airway pressure therapy is associated with HbA1c reduction in patients with severe OSA, in morbidly obese patients. and most obviously in those with significant weight lost during the follow-up. Our study underlines the importance to combine positive airway pressure use with adjustments in lifestyle to substantially modify metabolic complications in OSA.

Impact of sleep-disordered breathing on glucose metabolism among individuals with a family history of diabetes: the Nagahama study

STUDY OBJECTIVES

It is well known that a family history of diabetes (FHD) is a definitive risk factor for type 2 diabetes. It has not been known whether sleep-disordered breathing (SDB) increases the prevalence of diabetes in those with an FHD.

METHODS

We assessed SDB severity in 7,477 study participants by oximetry corrected by objective sleep duration determined by wrist actigraphy. Glycated hemoglobin ≥6.5% and/or current medication for diabetes indicated the presence of diabetes. In addition to the overall prevalence, the prevalence of recent-onset diabetes during the nearly 5 years before the SDB measurements were made was investigated.

RESULTS

Of the 7,477 participants (mean age: 57.9; range: 34.2-80.7; SD: 12.1 years; 67.7% females), 1,569 had an FHD. The prevalence of diabetes in FHD participants with moderate-to-severe SDB (MS-SDB) was higher than in those without SDB (MS-SDB vs without SDB: all, 29.3% vs 3.3% [P < .001]; females, 32.6% vs 1.9% [P < .001]; males, 26.2% vs 11.7% [P = .037]). However, multivariate analysis showed that MS-SDB was significantly associated with a higher prevalence of diabetes only in FHD-positive females (odds ratio [95% confidence interval]: females, 7.43 [3.16-17.45]; males, 0.92 [0.37-2.31]). Among the FHD-positive participants, the prevalence of recent-onset diabetes was higher in those with MS-SDB than those without SDB, but only in females (MS-SDB vs without SDB: 21.4% vs 1.1%; P < 0.001).

CONCLUSIONS

MS-SDB was associated with diabetes risk in females with an FHD, and future studies are needed on whether treatment of SDB in females with an FHD would prevent the onset of diabetes.

Diagnostic accuracy of the Berlin questionnaire and therapeutic effect of nasal continuous positive airway pressure in OSAHS patients with glucose metabolic dysfunction

PURPOSE

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is associated with alterations in glucose metabolism. The Berlin questionnaire (BQ) is effective in identifying subjects with high risk of OSAHS. However, its validity in patients with glucose metabolic dysfunction remains unclear. Our study aims to examine the diagnostic efficacy of the BQ in detecting OSAHS in patients with glucose metabolic dysfunction and to explore the effect of nasal CPAP on glucose metabolism.

METHODS

Patients with glucose metabolic dysregulation were first asked to complete the BQ and then recruited for polysomnogram (PSG). The diagnostic accuracy of the BQ and the relationships between groups with normal glucose tolerance (NGT), elevated fasting blood glucose (IFG), impaired glucose tolerance (IGT), and diabetes mellitus (DM) were analyzed. Subjects with both OSAHS and glucose dysregulation received CPAP treatment and underwent an oral glucose tolerance test. Changes in apnea-hypopnea indices (AHI) and glycemic parameters were calculated to determine the efficacy of CPAP.

RESULTS

Glycosylated hemoglobin and insulin levels were statistically different between the high-risk and low-risk groups according to the BQ. For diagnosis of subjects with OSAHS who also had glucose metabolic dysfunction, the sensitivity and specificity of the BQ using AHI cut-off values at 5 events per hour were 73% and 67%. CPAP therapy effectively reduced the blood glucose, HOMA-IR, and insulin levels.

CONCLUSIONS

The BQ can be considered to be an effective and economical screening tool for patieints with OSAHS who also have glucose metabolic dysfunction. Treatment with CPAP may improve glycemic parameters.

Update on Research and Practices in Major Sleep Disorders: Part I. Obstructive Sleep Apnea Syndrome

PURPOSE

The purpose of this first of two review articles providing an update on sleep disorders was to examine the pathophysiology, epidemiology, and treatment of obstructive sleep apnea (OSA). OSA is a common sleep disorder whose prevalence is similar to asthma. As with other sleep disorders, OSA has a broad impact on individuals, affecting their daily behaviors, cognitive abilities, and performance, and putting them at increased risk for accidents, mood disorders, cancer, cardiovascular disease, and hypertension. Thus, early recognition and management, much of which can be implemented by nurses, can reduce health and accident risks and improve daily functioning.

METHODS

This narrative review utilized medical databases such as PubMed to identify relevant English language original and systematic review articles predominantly from peer-reviewed journals from 2012 to 2018. However, as background, findings from classic articles prior to 2012 were also included.

CLINICAL RELEVANCE

OSA is a common condition with considerable impact on daily functioning and potential for accidents and serious comorbidities such as hypertension, cardiovascular disease, diabetes, and depressed mood. The impairments and comorbidities associated with OSA can be reduced through early detection, encouraging treatment, providing education about sleep and OSA, and, importantly, promoting adherence to the predominant therapy, positive airway pressure.

Witnessed sleep apneas together with elevated plasma glucose are predictors of COPD exacerbations

Objective

Sleep apnea and elevated plasma glucose associates with inflammation which associates with the risk of COPD exacerbations. We investigated the risk of exacerbations in individuals with COPD, witnessed sleep apneas, and elevated plasma glucose.

Methods

From the Copenhagen City Heart Study cohort, we identified 564 individuals with COPD (forced expiratory volume in 1 sec divided by forced vital capacity, FEV₁/FVC<0.70), no asthma, above 40 years of age, and more than 10 pack-years of smoking history, with information on witnessed apneas and levels of plasma glucose. We prospectively recorded hospital admissions with COPD exacerbations during maximum available follow-up (26.3 years; mean 10.7 years). Cox-regression analyses were used to analyze the risk of COPD exacerbations.

Results

We identified 74 (13%) individuals with sleep apnea without elevated plasma glucose, 70 (12%) had elevated plasma glucose (above 6.9 mM (>125 mg/dL)) without sleep apnea and 11 individuals had the presence of both conditions. In univariable analysis, witnessed apneas together with elevated plasma glucose had a high risk of exacerbations, hazard ratio (HR) = 5.81 (2.34–14.4, p = 0.0001) compared to those without sleep apnea and without elevated plasma glucose. Multivariable analysis, adjusting for several risk factors of exacerbations, showed a similar result, HR = 3.45 (1.13–10.5, p = 0.03). Both presence of sleep apnea without elevated plasma glucose and the presence of elevated plasma glucose without sleep apnea showed no associations with the risk of exacerbations.

Conclusions

Witnessed sleep apneas in COPD are associated with increased risk of exacerbations, but only among those with elevated plasma glucose.

Obstructive sleep apnea and liver injury in severely obese patients with nonalcoholic fatty liver disease

OBJECTIVES

Obstructive sleep apnea (OSA) and nonalcoholic fatty liver disease (NAFLD) are common in subjects with severe obesity. It has been suggested that insulin resistance and systemic inflammation may play a role in the development of nonalcoholic steatohepatitis (NASH), but the mechanisms remain controversial. The aim of this study was to explore the influence of OSA on liver injury and its potential mechanisms in severely obese patients with NAFLD.

METHODS

Severely obese patients requiring bariatric surgery were consecutively recruited between November 2017 and June 2018. Demographic, biochemical, liver ultrasound, and ambulatory polygraph data were collected.

RESULTS

One hundred fifty-three subjects with liver ultrasound-verified NAFLD were classified into three groups according to the apnea-hypopnea index (AHI). The level of serum alanine aminotransferase (ALT) and gamma-glutamyl transpeptidase (GGT) tended to increase with more severe OSA (P = 0.024 and P = 0.004, respectively). In the unadjusted analysis, both ALT and GGT were positively correlated with AHI, oxygen desaturation index, percentage of total sleep time spent with oxyhemoglobin saturation below 90%, male sex, homeostasis model assessment of insulin resistance (HOMA-IR), and total cholesterol, while liver enzymes were negatively related to lowest oxygen saturation. In multiple regression analysis, AHI (odds ratio (OR) = 1.052, P = 0.044) and HOMA-IR (OR = 1.135, P = 0.001) were independent risk factors for an elevated ALT level. High-sensitivity C-reactive protein (hs-CRP) was positively associated with BMI and GGT (r = 0.349 and r = 0.164 (P < 0.05), respectively), and no correlation was found between hs-CRP and AHI or other parameters of hypoxia. hs-CRP and GGT remained significantly correlated after adjusting for confounding parameters (OR = 2.509, P = 0.013).

CONCLUSIONS

OSA may play a role in liver injury among severely obese individuals with NAFLD. Insulin resistance and systemic inflammation were possible contributing factors in this process.

Non-sleepy obstructive sleep apnoea: to treat or not to treat?

Non-sleepy obstructive sleep apnoea (OSA) is thought to have a prevalence of around 20-25% in industrialised countries. However, the question of whether it should be routinely treated or not is controversial. This review collates the results from recent randomised controlled trials addressing OSA and examines whether treating the condition leads to improvements in quality of life and reduced cardiometabolic dysfunction, comorbidities generally attributed to untreated obstructive sleep apnoea/hypopnoea syndrome.

Sleep Apnea and Sleep Habits: Relationships with Metabolic Syndrome

Excess visceral adiposity is a primary cause of metabolic syndrome and often results from excess caloric intake and a lack of physical activity. Beyond these well-known etiologic factors, however, sleep habits and sleep apnea also seem to contribute to abdominal obesity and metabolic syndrome: Evidence suggests that sleep deprivation and behaviors linked to evening chronotype and social jetlag affect eating behaviors like meal preferences and eating times. When circadian rest and activity rhythms are disrupted, hormonal and metabolic regulations also become desynchronized, and this is known to contribute to the development of metabolic syndrome. The metabolic consequences of obstructive sleep apnea syndrome (OSAS) also contribute to incident metabolic syndrome. These observations, along with the first sleep intervention studies, have demonstrated that sleep is a relevant lifestyle factor that needs to be addressed along with diet and physical activity. Personalized lifestyle interventions should be tested in subjects with metabolic syndrome, based on their specific diet and physical activity habits, but also according to their circadian preference. The present review therefore focuses (i) on the role of sleep habits in the development of metabolic syndrome, (ii) on the reciprocal relationship between sleep apnea and metabolic syndrome, and (iii) on the results of sleep intervention studies.

The Veterans Affairs Continuous Positive Airway Pressure Use and Diabetic Retinopathy Study

SIGNIFICANCE

Obstructive sleep apnea has been linked to the development and progression of diabetic retinopathy. In this study, diabetic patients compliant with continuous positive airway pressure therapy (CPAP) for sleep apnea were less likely to have retinopathy, emphasizing the benefits and potential therapeutic role of CPAP in individuals with both conditions.

PURPOSE

The aim of this study was to compare the prevalence of diabetic retinopathy in type 2 diabetic patients with obstructive sleep apnea who were compliant with CPAP therapy with those who were not compliant with CPAP therapy.

METHODS

A retrospective cross-sectional review of type 2 diabetic patients using CPAP for obstructive sleep apnea was conducted. The prevalence of retinopathy was identified, and groups with and without retinopathy were compared using univariate analyses and multivariate logistic regression.

RESULTS

The prevalence of retinopathy was 19.6% (n = 321). Retinopathy was significantly less prevalent in those compliant with CPAP (odds ratio, 0.54; 95% confidence interval, 0.31 to 0.94; P = .04). The relationship remained statistically significant when adjusting for other factors known to impact the course of diabetic eye disease.

CONCLUSIONS

Increased CPAP compliance may mitigate the risk of developing diabetic retinopathy in type 2 diabetic patients with obstructive sleep apnea.

Holistic Management of Obstructive Sleep Apnea: Translating Academic Research to Patient Care

A holistic approach is pertinent in managing obstructive sleep apnea (OSA). It goes beyond integrated multidisciplinary assessment and management in the hospital setting. Although clinicians should be aware of different treatment modalities and adjunctive measures, proactive management of OSA is as important. The future of OSA management lies in identifying patients at risk of developing OSA and developing strategy to prevent OSA from taking root. It involves active screening of patients with OSA and treating them and identifying patients with OSA with high risk of preventable serious morbidity and death and intervening early to prevent these from happening.

Upper airway stimulation in obstructive sleep apnea improves glucose metabolism and reduces hedonic drive for food

Upper airway stimulation is a new and effective second-line treatment for obstructive sleep apnea, but possible consequences on glucose metabolism and central regulation of food intake are unclear. Twenty patients were prospectively studied before and 12 months after obstructive sleep apnea treatment by upper airway stimulation. Respiratory parameters and daytime sleepiness were assessed to document effectiveness of treatment. Glucose metabolism was assessed by the oral glucose tolerance test, and hedonic versus homeostatic drive to eat was characterized. At 12 months, upper airway stimulation significantly improved measures of obstructive sleep apnea (all p < 0.01). Despite no change in body weight, fasting C-peptide insulin resistance index (p = 0.01) as well as insulin and C-peptide levels at 60 min during the oral glucose tolerance test (p < 0.02) were reduced. Hedonic drive to eat was strongly reduced (p < 0.05), while leptin and ghrelin remained unchanged (p > 0.15). Upper airway stimulation is effective in treatment of obstructive sleep apnea and improves glucose metabolism. Reduced hedonic drive to eat might contribute to these metabolic improvements. These promising findings are in need for long-term controlled evaluation of metabolic sequelae of upper airway stimulation and to mechanistically evaluate the metabolic benefits of upper airway stimulation in patients with obstructive sleep apnea.

Sleep apnea and type 2 diabetes

The aim of the present review was to clarify the association between obstructive sleep apnea (OSA) and type 2 diabetes, and discuss the therapeutic role of continuous positive airway pressure (CPAP) in type 2 diabetes. OSA patients are more likely than non-OSA populations to develop type 2 diabetes, while more than half of type 2 diabetes patients suffer from OSA. Similar to Western countries, in the East Asian population, the association between these two disorders has also been reported. CPAP is the primary treatment for OSA, but the effect of CPAP on comorbid diabetes has not been established. CPAP improved glucose metabolism determined by the oral glucose tolerance test in OSA patients, and several studies have shown that CPAP improves insulin resistance, particularly in obese populations undergoing long-term CPAP. Diabetes is associated with other sleep-related manifestations as well, such as snoring and excessive daytime sleepiness. Snoring is associated with the development of diabetes, and excessive daytime sleepiness appears to modify insulin resistance. Well-designed studies are required to clarify the therapeutic effect of CPAP on diabetes. As both diabetes and OSA lead to cardiovascular disease, clinicians and healthcare professionals should be aware of the association between diabetes and OSA, and should take CPAP and health-related behaviors into consideration when treating patients with diabetes and/or OSA.

CPAP in patients with obstructive sleep apnea and type 2 diabetes mellitus: Systematic review and meta-analysis

INTRODUCTION

Obstructive sleep apnea hypopnea syndrome (OSAHS) is a prevalent condition across the world; it co-exists with others metabolic diseases, such as central obesity, dyslipidemia, and arterial hypertension. These associations increase the cardiovascular risk and mortality. Observational studies have reported a strength association between OSA and type 2 Diabetes Mellitus (T2DM) and continuous positive airway pressure (CPAP) is recommended for moderate to severe OSAHS.

OBJECTIVE

To summarize the evidence of CPAP in T2DM patients with OSAHS.

METHODS

A compressive search in Medline, Cochrane, Ovids, Epistemonikos, and DARE was performed. Two reviewers evaluated included studies, extracted data, carried out quality assessment and summarized the result. Pooled data was evaluated by meta-analysis and summaries of results and evidence grading were performed through the GRADE method.

RESULTS

Six randomized controlled trials (RCTs), including a total of 581 participants. Treatment with CPAP showed no effectiveness regarding changing glycated hemoglobin (HbA1c) levels at 12 or 24 weeks after treatment; (Mean difference= -0.10; Confidence interval -0.25 to 0.04) (GRADE: MODERATE). Subgroup analysis by adherence to CPAP (> 4 hours or < 4 hours) confirmed these results. Other indirect outcomes, such as change in fasting glucose levels, were similar in CPAP population and placebo.

DISCUSSION

This systematic review and meta-analysis evaluates the evidence regarding the efficacy of CPAP in patients with T2DM and OSAHS. In conclusion, CPAP does not improve glycemic control measure as HbA1c.

Obstructive sleep apnoea and Type 2 diabetes mellitus: are they connected?

Obstructive sleep apnoea (OSA), a sleep-related breathing condition, is diagnosed based on a patient's apnoea-hypopnea index from a sleep study, and the presence or absence of symptoms. Diabetes mellitus (DM) and OSA share a significant common risk factor, obesity, with all three conditions contributing to the risk of developing cardiovascular diseases. The pathophysiological links between OSA and DM are still unclear, but intermittent hypoxia may be an important mechanism. More awareness of the possible link between OSA and DM is needed, given their increasing prevalence locally and worldwide. Continuous positive airway pressure is the standard treatment for OSA, while weight loss through dietary and lifestyle modifications is important to holistically manage patients with either condition. There is currently insufficient evidence to support the benefits of screening every diabetic patient for OSA. However, diabetic patients with symptoms suggestive of OSA should be referred to a sleep specialist for further evaluation.

A Case of Concomitant Obstructive Sleep Apnea and Non-Alcoholic Steatohepatitis Treated With CPAP Therapy

Obstructive sleep apnea syndrome is a disorder of sleep breathing that is a result of recurrent and intermittent hypoxia during sleep induced by the repeated partial or complete collapse of the upper airway, eventually causing chronic intermittent hypoxia. Non-alcoholic fatty liver disease is divided into non-alcoholic fatty liver and non-alcoholic steatohepatitis. Animal and human studies showed that obesity is associated with chronic liver hypoxia, even in the presence of systemic normoxia causing inflammation and release of cytokines. A "two-hit" model has been proposed. The first hit is characterized by insulin resistance and excess hepatic lipid accumulation secondary to abnormal fatty acid metabolism. Oxidative stress and inflammation are thought to comprise the second hit. Gold standard for the diagnosis of non-alcoholic steatohepatitis is a liver biopsy. Many clinical scores and non-invasive tools are used for the diagnosis of non-alcoholic steatohepatitis. Conservative management with lifestyle modifications including diet, exercise and weight loss remains the therapy of choice today. We present a case report of a 39-year-old man who was diagnosed with concomitant non-alcoholic steatohepatitis and severe obstructive sleep apnea. He was started treatment with continuous positive airway pressure and demonstrated excellent adherence to therapy for 6 years, with concomitant obstructive sleep apnea and non-alcoholic steatohepatitis which reversed with prolonged optimal continuous positive airway pressure therapy. Physical examination remained unremarkable except for morbid obesity. His abdominal girth, as well as body mass index, remained unchanged. After 6 years of optimal continuous positive airway pressure therapy, liver enzymes and relevant lipid panel normalized, suggesting reversal of non-alcoholic steatohepatitis.

Effect of CPAP therapy on liver disease in patients with OSA: a review

Obstructive sleep apnea (OSA) may play an important role in the progression of nonalcoholic fatty liver disease (NAFLD).The effect of continuous positive airway pressure (CPAP) treatment, the first-line therapy for OSA, on liver disease in OSA patients is still debated. We provide this review of previous studies to summarize the effects of CPAP treatment on liver disease in OSA patients in aspects of liver function, liver steatosis, fibrosis, and incidence of liver disease. CPAP treatment may be beneficial to liver disease in subjects with OSA independent of metabolic risk factors, but a sufficiently long therapeutic duration (perhaps greater than 3 months) may be needed to achieve these positive effects. Though the mechanism of impact of CPAP treatment on liver in OSA patients is unclear, the influence of CPAP treatment on the factors of the "Two-hit" hypothesis (insulin resistance, fatty acids dysregulation, oxidative stress, and inflammation) may be a reasonable explanation.

Aiding sleep in type 2 diabetes: therapeutic considerations

Insomnia and obstructive sleep apnoea (OSA) are more prevalent in patients with type 2 diabetes than in the general population. Both insomnia and OSA have been linked to cardiometabolic alterations (eg, hypertension, increased activity of the sympathetic nervous system, and systemic insulin resistance) that can exacerbate the pathophysiology of type 2 diabetes. Improvement of sleep in patients with diabetes could therefore aid the treatment of diabetes. To help health practitioners choose the best clinical tool to improve their patients' sleep without detrimentally affecting glucose regulation, this Review critically analyses the effects of common treatments for insomnia and OSA on both sleep and glucose metabolism in patients with type 2 diabetes. These treatments include pharmaceutical sleep aids (eg, benzodiazepine receptor agonists, melatonin) and cognitive behavioural therapy for insomnia, continuous positive airway pressure for OSA, and lifestyle interventions.

Distinct impacts of sleep-disordered breathing on glycemic variability in patients with and without diabetes mellitus

BACKGROUND

Sleep-disordered breathing (SDB) is highly prevalent in patients with diabetes mellitus (DM) and heart failure (HF) and contributes to poor cardiovascular outcomes. Enlarged glycemic variability (GV) is a risk factor of cardiac events independently of average blood glucose level, but the influence of SDB on GV is uncertain. In this study, we examined whether the impact of SDB on GV is modified by the presence of DM with or without HF.

METHODS AND RESULTS

Two hundred three patients (67.5±14.1 [SD] years old, 132 males) who were admitted to our institute for examination or treatment of DM and/or HF underwent continuous glucose monitoring and polysomnography. Both HbA1c (8.0±2.0 vs. 5.7±0.4%) and mean amplitude of glycemic excursion (MAGE, median: 95.5 vs. 63.5 mg/dl) were significantly higher in a DM group (n = 100) than in a non-DM group (n = 103), but apnea-hypopnea index (AHI: 29.0±22.7 vs. 29.3±21.5) was similar in the two groups. AHI was correlated with log MAGE in the non-DM group but not in the DM group, and multivariate regression analysis revealed that AHI was an independent variable for log MAGE in the non-DM group but not in the DM group. We then divided the non-DM patients into two subgroups according to BNP level (100 pg/ml). AHI was positively correlated with log MAGE (r = 0.74, p<0.001) in the non-DM low-BNP subgroup, but such a correlation was not found in the non-DM high-BNP subgroup. Continuous positive airway pressure (CPAP) reduced MAGE from 75.3 to 53.0 mg/dl in the non-DM group but did not reduce MAGE in the DM group.

CONCLUSION

Severity of SDB was associated with higher GV, but DM as well as HF diminished the contribution of SDB to GV. Treatment with CPAP was effective for reduction of GV only in patients without DM.

Obstructive sleep apnoea and polycystic ovary syndrome: A comprehensive review of clinical interactions and underlying pathophysiology

Polycystic ovary syndrome (PCOS) is the most prevalent endocrine disorder in women of reproductive age. PCOS is associated with multiple comorbidities including, obesity, insulin resistance and type 2 diabetes, as well as mood disorders and impaired quality of life (QoL). Obstructive sleep apnoea (OSA) is also a common medical condition that is often undiagnosed, particularly in women. OSA is associated with a similar spectrum of comorbidities to that observed in PCOS, including manifestations of the metabolic syndrome and impaired QoL, whilst obesity frequently constitutes a common denominator in the pathophysiology of both OSA and PCOS. Hence, it is not surprising that OSA and PCOS may coexist in women of reproductive age, and the current clinical guidelines on the management of PCOS recommend screening for OSA symptoms in overweight/obese women with PCOS. In this review, we examine the relationship between OSA and PCOS and explore the potential underlying mechanisms that link these two conditions.

Insulin Resistance and Hypertension in Obese Youth With Sleep-Disordered Breathing Treated With Positive Airway Pressure: A Prospective Multicenter Study

STUDY OBJECTIVES

There is evidence that cardiometabolic disease associated with obesity and sleep-disordered breathing (SDB) in adults is present in youth. SDB is often treated with positive airway pressure (PAP) in youth with obesity. Our aims were to determine: (1) the prevalence of cardiometabolic disease and (2) whether PAP improves markers of cardiometabolic disease, in youth with obesity and newly diagnosed moderate-severe SDB.

METHODS

A prospective multicenter cohort study was conducted in youth (8 to 16 years old) with obesity, prescribed PAP therapy for newly diagnosed moderate-severe SDB. Assessments occurred at baseline and at 6 and 12 months. Outcomes included markers of insulin resistance (change in homeostasis model assessment of insulin resistance (HOMA-IR) at 6 months = primary outcome), hypertension (24-hour ambulatory/blood pressure) and inflammation (high-sensitivity C-reactive protein: hs-CRP).

RESULTS

Twenty-seven participants were enrolled. Of those with baseline testing available, 10/25 (40%) had HOMA-IR above the 97th percentile, 10/23 (44%) were hypertensive, 16/23 (70%) had loss of nocturnal blood pressure dip and hs-CRP was elevated in 16/27 (64%). There were no significant changes over time in markers of metabolic dysfunction or blood pressure, nor between PAP-adherent and non-adherent subgroups.

CONCLUSIONS

In youth with obesity and SDB, metabolic dysfunction and hypertension were highly prevalent. There were no statistically significant improvements in cardiometabolic markers 1 year after the prescription of PAP therapy, although clinically relevant improvements were seen in insulin resistance and systolic blood pressure load, important predictors of future risk of cardiovascular disease. Larger, longer-term studies are needed to determine whether PAP improves cardiometabolic outcomes in obese youth.

COMMENTARY

A commentary on this article appears in this issue on page 1025.

Effects of positive airway pressure therapy on cardiovascular and metabolic markers in males with obstructive sleep apnea

INTRODUCTION

Obstructive sleep apnea syndrome (OSAS) is associated with cardiovascular/metabolic complications. Some analytical parameters (homocysteine, glycemic and lipidic profiles) are recognized markers of these consequences. Limited data is available on the association of these markers and OSAS's severity/response to positive airway pressure therapy (PAP).

MATERIAL AND METHODS

In this prospective study we analyzed polysomnographic and analytical data of male patients admitted to sleep laboratory. The aim was to evaluate metabolic/cardiovascular markers in snorers and OSAS patients, to relate with sleep parameters and PAP response. One-hundred and three patients were included, and 73 (71%) were OSAS patients. OSAS patients were similar to snorers except for higher body mass index (BMI) and dyslipidemia. Severe OSAS patients showed higher glycemia, HbA1c, insulin, and insulin resistance, and lower HDL cholesterol in comparison to mild-moderate (p<0.05, p<0.05, p<0.001, p<0.001, p<0.05, respectively). Glycemic profile and triglycerides were slightly correlated with OSAS severity. 46 OSAS patients were submitted to 6 months of PAP, with a statistical decrease in mean values of homocysteine, glycemia, total and LDL cholesterol (p<0.05, p<0.05, p<0.05, respectively), and in glycemia and LDL cholesterol in severe group only (p<0.05, p<0.05, respectively).

RESULTS

This study demonstrated an association between glucose metabolism parameters and triglycerides with OSAS severity underlying the complexity of the process leading to cardiovascular/metabolic complications in this disorder. Moreover, homocysteine, glycemic and lipidic profiles changed significantly after 6 months of PAP therapy in OSAS, supporting its cardiovascular and metabolic protective effect.

CONCLUSION

Our study has reinforced the importance of analytical cardiovascular/metabolic evaluation as complementary tool of diagnosis/treatment response in OSAS.

Obstructive sleep apnea and hormones - a novel insight

Obstructive sleep apnea (OSA), a disorder characterized by repetitive collapse of the upper respiratory tract during sleep, occurs in about 4% of middle-aged men and 2% of women. The incidence of the disorder is rising due to an increase in obesity and ageing of the population. Patients with obstructive sleep apnea are at elevated risk of some endocrinal and metabolic disorders, which may lead to serious consequences including shortening of life expectancy. The recognition and understanding of interactions between local upper airway dysfunction and its endocrinal consequences is therefore vital. In this review we will focus on the influence of OSA on bone metabolism and endocrine homeostasis.

Continuous positive airway pressure and diabetes risk in sleep apnea patients: A systemic review and meta-analysis

BACKGROUND

The study assessed the effect of continuous positive airway pressure (CPAP) therapy on the risk of developing type 2 diabetes by evaluating change in the homeostasis model assessment of insulin resistance (HOMA-IR) fasting blood glucose (FBG) and fasting insulin following CPAP treatment in non-diabetic patients and pre-diabetic with obstructive sleep apnea (OSA).

METHODS

Medline, PubMed, Cochrane, and EMBASE databases were searched until August 24, 2015. The analysis included randomized controlled trials (RCTs), two arm prospective studies, cohort studies, and retrospective studies. The primary outcome measure was change of HOMA-IR in pre-diabetic patients receiving CPAP treatment.

RESULTS

Twenty-three studies were included with 965 patients who had OSA. Nineteen studies were prospective studies and four were RCTs. CPAP therapy resulted in a significant reduction in the pooled standard difference in means of HOMA-IR (-0.442, P=0.001) from baseline levels compared with the control group. Change in FBG and fasting insulin from baseline levels was similar for the CPAP and control groups. For RCT studies (n=4), there was no difference in change in HOMA-IR or FBG levels from baseline between CPAP and control groups. The combined effect of RCTs showed that CPAP was associated with a significant reduction in change from baseline in fasting insulin than the control group (standardized diff. in means between groups=-0.479, P value=0.003).

CONCLUSION

These findings support the use of CPAP in non-diabetic and pre-diabetic patients with OSA to reduce change of HOMA-IR and possibly reduce the risk of developing type 2 diabetes in this patient population.

VAMONOS (Veterans Affairs' Metabolism, Obstructed and Non-Obstructed Sleep) Study: Effects of CPAP Therapy on Glucose Metabolism in Patients with Obstructive Sleep Apnea

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) and type 2 diabetes mellitus (T2DM) are prevalent disorders that pose increased risk of cardiovascular disease and death. The objective of this study was to clarify if continuous positive airway pressure (CPAP) therapy for OSA affects T2DM control and emergence.

METHODS

Point-of-care, comparative effectiveness study; cross-sectional and longitudinal analyses.

RESULTS

Our cohort included 928 consecutive patients; 13% were women; 36% were Caucasians and 61% African-Americans. OSA was diagnosed in approximately 738 patients and CPAP was initiated in 718 patients; median duration of therapy was 5 mo (25% to 75% interquartile range [IQR] 3-14). Patients with OSA used CPAP therapy for a median duration of 4.8 h, 34.5% of the nights. Adherence to CPAP was prespecified as follows: good (≥ 70% nights and ≥ 4 h/night), excellent (≥ 80% nights and ≥ 6 h/night) or outstanding (≥ 90% of nights and 8 h/night). Based on objective data, good, excellent, and outstanding compliance were found in only 30%, 20%, and 6%, respectively. Three percent of subjects without CPAP follow-up and less than 4% of those nonadherent to CPAP therapy (based on the established criteria) developed incident T2DM. Incident T2DM developed in only 0.8% of those with good compliance and in none (0%) of those in the excellent and outstanding groups. During follow-up, median weight change was +0.3 kg (IQR -1.8 to 2.7).

CONCLUSIONS

We found that an outstanding compliance to CPAP reduced fasting blood glucose in patients with OSA. Longitudinally, higher levels of therapeutic adherence may affect the rate of incident impaired fasting glucose, prediabetes, and T2DM, despite the observed weight gains.

COMMENTARY

A commentary on this article appears in this issue on page 365.

The Link Between Obstructive Sleep Apnea and Cardiovascular Disease

Obstructive sleep apnea (OSA) is common in the general population and highly prevalent in patients with cardiovascular disease. In this paper, we review (1) the pathophysiological mechanisms of OSA that may causally contribute to cardiovascular disease; (2) current evidence regarding the association between OSA and hypertension, stroke, ischemic heart disease, heart failure, atrial fibrillation, and cardiovascular mortality; and (3) the impact of continuous positive airway pressure (CPAP) treatment on cardiovascular risk factors and outcomes. We emphasize the importance of obesity as a comorbidity of OSA and a confounder in the association between OSA and cardiovascular disease. We also discuss the importance of addressing obesity in patients with OSA, as a strategy to reduce the burden of cardiovascular risk factors in this population. Implications for the approach of patients' OSA in clinical practice and future research directions are discussed.

Non-Invasive Ventilation (NIV) and Homeostatic Model Assessment (HOMA) Index in Stable Chronic Obstructive Pulmonary Disease (COPD) Patients with Chronic Hypercapnic Respiratory Failure: A Pilot Study

The effects of Non-invasive Ventilation (NIV) on Insulin Resistance (IR) in stable Chronic Obstructive Pulmonary Disease (COPD) patients have not been fully explored. The aim of this study was to assess the effects of NIV on IR and adiponectin levels during one year application of NIV in stable COPD patients with Chronic Hypercapnic Respiratory Failure. Twenty-five (25) stable COPD patients with Chronic Hypercapnic Respiratory Failure and with no self-reported comorbidities completed the study. NIV was administered in the spontaneous/timed mode via a full face mask using a bi-level positive airway pressure system. Spirometry, blood pressure, arterial blood gases, dyspnea, daytime sleepiness, serum fasting glucose and insulin levels were assessed. IR was assessed with the calculation of the Homeostatic Model Assessment (HOMA) index. Adiponectin was measured with radioimmunoassay. Study participants were re-evaluated on the first, third, sixth, ninth and twelfth month after the initial evaluation. There was a significant improvement in FEV1 values from the first month (34.1 ± 11.6% vs 37 ± 12.3%, p = 0.05). There was a significant decrease in IR by the ninth month of NIV use (3.4 ± 2.3 vs 2.2 ± 1.4, p < 0.0001), while adiponectin levels significantly improved from the first month of NIV use. Stepwise regression analysis revealed that baseline HOMA index was associated with paCO2 (β = 0.07 ± 0.02, p = 0.001), while baseline adiponectin levels were associated with FVC (β = 0.05 ± 0.02, p = 0.035) and the concentration of serum bicarbonate (HCO3-) (-β = 0.18 ± 0.06, p = 0.002). Insulin sensitivity and glucose metabolism as well as adiponectin levels improved along with the improvements in respiratory failure.

Diabetic kidney disease and obstructive sleep apnea: a new frontier?

PURPOSE OF REVIEW

Obstructive sleep apnea (OSA) has been shown to be an independent risk factor for the development and progression of diabetes mellitus. Interestingly, there is also a strong correlation between OSA and the development and progression of chronic kidney disease (CKD). As diabetes mellitus is the most common cause of CKD, in this review we summarize the current literature regarding this interconnecting relationship between OSA, CKD, and diabetes mellitus. The literature increasingly supports a bidirectional relationship between CKD and OSA among diabetes mellitus patients leading to an increased rate of progression of diabetic nephropathy.

RECENT FINDINGS

There is growing evidence that among patients with diabetes mellitus, OSA may be a strong risk factor for the development of diabetic nephropathy. The treatment of OSA in CKD patients may play a role in attenuating the rate of the progression of CKD.

SUMMARY

Clinicians should have a low threshold for evaluating diabetic patients with CKD for OSA. Further studies examining if treatment of OSA would improve the outcomes of CKD patients in general and diabetic CKD patients in particular are needed.

Glucose tolerance and cardiovascular risk biomarkers in non-diabetic non-obese obstructive sleep apnea patients: Effects of long-term continuous positive airway pressure

BACKGROUND

Insulin resistance, glucose dyshomeostasis and oxidative stress are associated to the cardiovascular consequences of obstructive sleep apnea (OSA). The effects of a long-term continuous positive airway pressure (LT-CPAP) treatment on such mechanisms still remain conflicting.

OBJECTIVE

To investigate the effect of LT-CPAP on glucose tolerance, insulin sensitivity, oxidative stress and cardiovascular biomarkers in non-obese non-diabetic OSA patients.

PATIENTS & METHODS

Twenty-eight apneic, otherwise healthy, men suffering from OSA (mean age = 48.9 ± 9.4 years; apnea-hypopnea index = 41.1 ± 16.1 events/h; BMI = 26.6 ± 2.8 kg/m(2); fasting glucose = 4.98 ± 0.37 mmol/L) were evaluated before and after LT-CPAP by an oral glucose tolerance test (OGTT), measuring plasma glucose, insulin and proinsulin. Glycated hemoglobin, homeostasis model assessment resistance insulin, blood lipids, oxidative stress, homocysteine and NT-pro-brain natriuretic peptide (NT-proBNP) were also measured.

RESULTS

LT-CPAP treatment lasted 13.9 ± 6.5 months. At baseline, the time spent at SaO2<90%, minimal and mean SaO2 were associated with insulin area under the curve during OGTT (r = 0.448, P = 0.011; r = -0.382; P = 0.047 and r = -0.424; P = 0.028, respectively) and most other glucose/insulin homeostasis biomarkers, as well as with homocysteine (r = 0.531, P = 0.006; r = -0.487; P = 0.011 and r = -0.409; P = 0.034, respectively). LT-CPAP had no effect on all the OGTT-related measurements, but increased plasma total antioxidant status (+7.74%; P = 0.035) in a duration-dependent manner (r = 0.607; P < 0.001), and decreased both homocysteine (-15.2%; P = 0.002) and NT-proBNP levels (-39.3%; P = 0.002).

CONCLUSIONS

In non-obese non-diabetic OSA patients, nocturnal oxygen desaturation is strongly associated to insulin resistance. LT-CPAP does not improve glucose homeostasis nor insulin sensitivity but has a favorable effect on antioxidant capacity and cardiovascular risk biomarkers.