Effects of sleep apnea severity on glycemic control in patients with type 2 diabetes prior to continuous positive airway pressure treatment

The relationship between obstructive sleep apnea and haemoglobin A1c and the moderating role of glycaemic status in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL)

This study investigated the relationship between obstructive sleep apnea and haemoglobin A1c (HbA1c) among Hispanics/Latinos in the United States and assessed whether this relationship was moderated by glycaemic status. This was a cross-sectional analysis of the Hispanic Community Health Study/Study of Latinos cohort. The sample consisted of 13,394 participants with valid measures of obstructive sleep apnea, HbA1c, and study covariates. Obstructive sleep apnea was assessed with the apnea-hypopnea index and categorised as obstructive sleep apnea if the apnea-hypopnea index was ≥5 events/h. HbA1c measures were obtained through fasting blood samples. Fasting plasma glucose (FPG), 2-h post-load plasma glucose (2h-PG) and use of antihyperglycaemic medications were used to define glycaemic status (i.e., normoglycaemia [FPG < 5.6 mmol/L (< 100 mg/dL) and 2h-PG < 7.8 mmol/L (140 mg/dL)], prediabetes [FPG 5.6-6.9 mmol/L (100-125 mg/dL), and/or 2h-PG 7.8-11.0 mmol/L (140-199 mg/dL)], diabetes without treatment [FPG > 7.0 mmol/L (≥ 126 mg/dL) and/or 2h-PG ≥ 11.1 mmol/L (≥ 200 mg/dL)], and diabetes with treatment. Multivariable linear regression was used to calculate adjusted least square means. Overall, 25.9% of the sample had obstructive sleep apnea and 49.2% had normal glycaemic levels, 36.1% had prediabetes, 6.5% diabetes without receiving treatment, and 8.3% diabetes and undergoing treatment for it. Participants with obstructive sleep apnea had significantly higher adjusted mean HbA1c (adjusted mean [standard error] 5.85 [0.03)]) than those without (5.70 [0.02)]; p < 0.001). Models stratified by diabetes status showed that the association between obstructive sleep apnea (versus not) and higher HbA1c was only for participants with normal glycaemic status (adjusted mean [standard error] 5.27 [0.01] versus 5.30 [0.01]; p = 0.013) and prediabetes (5.59 [0.01] versus 5.66 [0.01]; p < 0.001). In conclusion, obstructive sleep apnea was associated with higher HbA1c in a diverse sample of Hispanic/Latino adults in the United States. This association was present only for participants with normal glycaemic status or with prediabetes. Studies are needed to further understand the clinical implications of the association between obstructive sleep apnea and HbA1c according to glycaemic status.

Obstructive sleep apnea: Beyond the dogma of obesity!

Obstructive sleep apnea (OSA) has long been studied in patients with obesity and type 2 diabetes mellitus (T2DM), due to the fact that both disorders are commonly associated with an increased body mass index (BMI). However, a link between OSA and non-obese diabetic patients is still not very elaborated, nor heavily explored. In this review, we elucidate some proposed mechanisms for the link between OSA and diabetic patients both with and beyond obesity, shedding the light on the latter case. One such mechanism is oxidative stress, a phenomenon of reactive oxygen species (ROS) imbalance seen in both of the previously mentioned disorders. A plausible explanation for the OSA-induced ROS production is the repeating episodes of hypoxia and reperfusion and their effect on the mitochondrial electron transport chain. This paper explores the literature regarding ROS imbalance as the possible missing link between OSA and Diabetes Mellitus beyond obesity, while still mentioning other possible proposed mechanisms such as a dysregulated autonomic nervous system (ANS), as well as mechanical and craniofacial abnormalities. This paper also suggests a link between OSA and diabetic complications, while exploring the clinical progress made in treating the former disorder with anti-oxidant and hypo-glycemic drugs. If further investigated, these findings could help identify novel therapeutic interventions for the treatment of OSA and Diabetic patients.

Endocrine disorders in obstructive sleep apnoea syndrome: A bidirectional relationship

Obstructive sleep apnoea (OSA) is a common disorder characterized by recurrent episodes of apnoea or hypopnea due to total or partial pharyngeal collapse and temporary upper airway obstruction during sleep. The prevalence of OSA is increasing and currently affects about 30% of men and 13% of women in Europe. Intermittent hypoxia, oxidative stress, systemic inflammation, and sleep fragmentation resulting from OSA can provoke subsequent cardiometabolic disorders. The relationships between endocrine disorders and OSA are complex and bidirectional. Indeed, several endocrine disorders are risk factors for OSA. Compared with the general population, the prevalence of OSA is increased in patients with obesity, hypothyroidism, acromegaly, Cushing syndrome, and type 1 and 2 diabetes. In some cases, treatment of the underlying endocrine disorder can improve, and occasionally cure, OSA. On the other hand, OSA can also induce endocrine disorders, particularly glucose metabolism abnormalities. Whether continuous positive airway pressure (CPAP) treatment for OSA can improve these endocrine disturbances remains unclear due to the presence of several confounding factors. In this review, we discuss the current state-of-the-art based on the review of the current medical literature for key articles focusing on the bidirectional relationship between endocrine disorders and OSA and the effects of treatment. Screening of OSA in endocrine patients is also discussed, as it remains a subject of debate.

Effect of nocturnal hypoxemia on glycemic control among diabetic Saudi patients presenting with obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is a prevalent disease that is associated with an increased incidence of type II diabetes mellitus (DM) if left untreated. We aimed to determine the association between glycosylated hemoglobin (HbA1c) levels and both nocturnal hypoxemia and apnea-hypopnea index (AHI) among a Saudi patients with OSA.

METHODS

A cross-sectional study that enrolled 103 adult patients diagnosed with DM and confirmed to have OSA by full night attended polysomnography between 2018 and 2021. Those who presented with acute illness, chronic obstructive pulmonary disease (COPD)/restrictive lung diseases causing sleep-related hypoxemia, or no available HbA1c level within 6 months before polysomnography were excluded from the study. Univariate and multivariate linear regression analyses between HbA1c levels and parameters of interest were tested.

RESULTS

Sixty-seven (65%) of the studied population had uncontrolled DM (HbA1c ≥7%). In univariate regression analysis, there was a significant positive association between HbA1c, and sleep time spent with an oxygen saturation below 90% (T90), female gender, and body mass index (BMI) (p<0.05) but not AHI, or associated comorbidities (p>0.05). In the multivariate analysis, HbA1c was positively associated with increasing T90 (p<0.05), and ODI (p<0.05), but not with AHI (p>0.05).

CONCLUSION

Nocturnal hypoxemia could be an important factor affecting glycemic control in patients with OSA suffering from DM irrespective of the severity of both diseases.

Association between nocturnal hypoxemic burden and glucose metabolism

PURPOSE

To evaluate the association between a novel integrated event-based and hypoxemia-based parameter of polysomnography (PSG), hypoxemic load or HL100, and fasting blood glucose (FBG) and hemoglobin A1c (HbA1c) levels.

METHODS

Adult patients, who underwent an in-lab PSG at the University of Iowa Hospitals and Clinics with FBG or HbA1c levels, were included. Event-based parameter and hypoxemia-based parameter data were derived. HL100, defined as the integrated area of desaturation between the 100% oxygen saturation and the measured saturation levels during sleep divided by the total sleep time, was calculated by Python software. Demographic data and glycemic parameters within 1 year prior to PSG (FBG and HbA1c) were retrieved from chart review. Spearman correlation analysis and stepwise backward regression analysis were performed to determine independent predictors of FBG and HbA1c levels.

RESULTS

Of the 467 patients who underwent an in-lab PSG, 218 had FBG levels, 84 had HbA1c levels, and 118 had both values. All event-based and hypoxemia-based parameters, including HL100, were significantly correlated to FBG and HbA1c levels. Stepwise backward regression analyses, adjusted for age, sex, body mass index, and diabetes status, revealed that log HL100 was significantly related to FBG (B = 23.9, p = 0.010), but none of log event-based or hypoxemia-based parameters were found to be significantly related HbA1c levels.

CONCLUSIONS

HL100 was shown to be an independent predictor of FBG in this cohort, implying that any degree of desaturation below 100% could adversely affect glucose metabolism. HL100 may be useful for interpretation of sleep studies, risk stratification, and patient management purposes in the future.

Postprandial hyperglycemia in type 2 diabetes and obstructive sleep apnea

OBJECTIVES

Postprandial hyperglycemia is common in type 2 diabetes even in those with acceptable glycemic control and conveys an increased risk of cardiovascular morbidity and mortality. Although obstructive sleep apnea (OSA) has been associated with altered glucose metabolism, data regarding its association with postprandial hyperglycemia in type 2 diabetes are limited. Thus, the current study sought to characterize the association between OSA and postprandial hyperglycemia in adults with type 2 diabetes.

METHODS

A cross-sectional study of adults with type 2 diabetes was conducted. Home sleep testing was used to assess OSA severity as determined by the oxygen desaturation index (ODI). Self-monitoring of blood glucose (SMBG) was performed before and 2-h after breakfast, lunch, and dinner for three days. The association between OSA and glucose levels before and after each meal was examined using multivariable logistic regression.

RESULTS

The study sample consisted of 195 adults with 52% being men. OSA severity, as assessed by ODI quartiles, was associated with higher postprandial glucose values after dinner but not after breakfast or lunch. The adjusted odds ratios (95% confidence intervals) for a higher post-dinner glucose level for four ODI quartiles were 1.00 (Reference), 2.16 (0.96, 4.87), 2.23 (1.03, 4.83), and 2.58 (1.18, 5.94). Stratified analyses showed that this association was present in men but not women.

CONCLUSIONS

Increasing OSA severity is associated with postprandial hyperglycemia in type 2 diabetes and may contribute to impaired glycemic control. Future studies examining the impact of OSA treatment on glucose metabolism should consider meal-related glycemic excursions as a potential outcome.

The impact of sleep disorders on microvascular complications in patients with type 2 diabetes (SLEEP T2D): the protocol of a cohort study and feasibility randomised control trial

BACKGROUND

Obstructive sleep apnoea (OSA) is very common in patients with type 2 diabetes (T2D). We and others have shown that OSA was associated with diabetes-related microvascular complications in patients with T2D in cross-sectional and longitudinal studies and that compliance with continuous positive airway pressure (CPAP) reduced the progression of microvascular complications. Hence, we hypothesised that adequate CPAP reduces the development of microvascular complication in patients with T2D.

METHODS

SLEEP T2D is a cohort study with embedded feasibility, open-label, parallel-arm, randomised control trial (RCT) over 2 years. The primary aim is the feasibility of conducting a definitive RCT assessing the impact of CPAP on chronic kidney disease and other microvascular complications in patients with T2D. The main parameters are to assess willingness of participants to be randomised, follow-up rates, CPAP adherence/compliance, to optimise the choice of outcome measures for a substantive trial, and to identify the parameters for sample size calculations. The secondary aims of the study are related to the impact of CPAP, sleep-related disorders, and sleep chronotype on a variety of diabetes-related end points. The study participants were recruited from the T2D services in multiple NHS trusts across England. The main exclusion criteria for the cohort study are as follows: T1D, eGFR < 15 mL/min/1.73 m², known OSA, active malignancy or chronic kidney disease from reasons other than diabetes, pregnancy, professional drivers, and a history of falling asleep whilst driving within last 2 years. The main exclusion criteria from the RCT were as follows: Apnoea-Hypopnoea Index < 10 and Epworth Sleepiness Score ≥ 11. Study participants were extensively phenotyped clinically and biochemically. The OSA diagnosis was based on multichannel portable device (ApneaLink Air^TM, Resmed).

DISCUSSION

The feasibility RCT will help us design the future RCT to assess the impact of CPAP on diabetes-related microvascular complications. The cohort study will generate preliminary data regarding the impact of sleep quality, duration, and chronotype on diabetes-related outcomes which could lead to further mechanistic and interventional studies.

TRIAL REGISTRATION

ISRCTN, ISRCTN12361838 . Registered 04 April 2018, Protocol version: v5.0 02.12.19.

Sleep characteristics and HbA1c in patients with type 2 diabetes on glucose-lowering medication

INTRODUCTION

To examine the association of sleep duration, insomnia, and obstructive sleep apnea (OSA) with hemoglobin A1c (HbA1c) in a cohort of patients with type 2 diabetes (T2D) on glucose-lowering medications.

RESEARCH DESIGN AND METHODS

13 346 patients with T2D were included in the present analysis (mean age: 60.2 years; 56.6% were on antidiabetic drug monotherapy; 43.4% received at least two glucose-lowering medications). Sleep duration (short: ≤6 hours/day; normal: 7-8 hours/day; long: ≥9 hours/day) and frequency of insomnia symptoms were self-reported. The risk of OSA was considered high if at least two of the following conditions were fulfilled: regular snoring, frequent daytime sleepiness, and either obesity (≥30 kg/m²) or hypertension (systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg). Associations between sleep variables and HbA1c were investigated by analysis of covariance or linear regression (adjusted for, eg, participants' age, sex, ethnic background, and systolic blood pressure).

RESULTS

Long sleep duration and a high risk for OSA were independently associated with higher HbA1c values (long vs normal sleep duration: +0.10% (95% CI 0.03 to 0.18); high vs low risk for OSA: +0.07% (95% CI 0.02 to 0.11), both p=0.004). No robust association was found of short sleep duration and frequent insomnia symptoms with HbA1c. Finally, a positive dose-response association between the number of sleep problems per subject (range: 0-3) and HbA1c was observed (β=0.04% (0.02 to 0.06), p=0.002). However, all significant associations were small.

CONCLUSION

Screening for and treatment of sleep problems may help lower HbA1c levels in patients with T2D on glucose-lowering medications.

The association between sleep and diabetes outcomes - A systematic review

AIM

This study aimed to systematically review the prevalence of diagnosed sleep disorders in people with diabetes and to determine the association between sleep disorders and blood glucose levels and diabetes outcomes.

METHODS

We conducted a literature search in the following databases: MEDLINE (Pubmed), EMBASE, CINAHL, PsychInfo and Web of Science Citation Index. Meta-analysis (random-effects models) was conducted to estimate the prevalence of sleep disorders in people with diabetes.

RESULTS

Forty-one articles measured the prevalence of sleep disorders in adults with diabetes. The estimated pooled prevalence of sleep disorders in diabetes was estimated to be 52% (95% CI 42-63%). The highest pooled prevalence was observed for unspecified sleep apnea (69%; 95% CI: 59-78%), followed by obstructive sleep apnea (60%; 95% CI 39-80%), and restless leg syndrome (27%; 95% CI 20-34%). Eleven studies examined the association between sleep disorders and diabetes control and complications. The presence of comorbid sleep disorders was associated with increased diabetes outcomes.

CONCLUSIONS

Diagnosed sleep disorders are highly prevalent in people with diabetes. Sleep disorders are associated with diabetes outcomes, though there was considerable heterogeneity across studies.

Obstructive Sleep Apnea, Sleepiness, and Glycemic Control in Type 2 Diabetes

STUDY OBJECTIVES

Self-reported sleepiness is common in patients with obstructive sleep apnea (OSA) and is being increasingly recognized as an effect modifier of the association between OSA and cardiovascular outcomes. However, data on whether sleepiness modifies the association between OSA and glycemic outcomes are lacking. The current study sought to characterize the association between glycemic control and sleepiness in people with OSA and type 2 diabetes.

METHODS

Adults with non-insulin requiring type 2 diabetes and undiagnosed moderate to severe OSA were recruited from the community. Demographic data, Epworth Sleepiness Scale (ESS), hemoglobin A1c (HbA1c), as well a type III home sleep test were obtained. The association between self-reported sleepiness and glycemic control was examined using quantile regression.

RESULTS

The study cohort included 311 participants with 56% of the sample being men. Stratified analyses by sex demonstrated that self-reported sleepiness was associated with a higher HbA1c level, but this association was present only in men with a body mass index (BMI) < 35 kg/m². Mean HbA1c levels were higher by 0.57% (95% confidence interval: 0.11, 1.02) in men with an ESS ≥ 11 compared to men with an ESS < 11. No such association was observed in men with a BMI ≥ 35 kg/m² or in women of any BMI category.

CONCLUSIONS

The association between self-reported sleepiness and glycemic control in people with type 2 diabetes and moderate to severe OSA varies a function of BMI and sex. The noted differences in association should be considered when assessing possible treatment effects of therapy for OSA on metabolic outcomes.

Interactions between and Shared Molecular Mechanisms of Diabetic Peripheral Neuropathy and Obstructive Sleep Apnea in Type 2 Diabetes Patients

Type 2 diabetes (T2D) accounts for about 90% of all diabetes patients and incurs a heavy global public health burden. Up to 50% of T2D patients will eventually develop neuropathy as T2D progresses. Diabetic peripheral neuropathy (DPN) is a common diabetic complication and one of the main causes of increased morbidity and mortality of T2D patients. Obstructive sleep apnea (OSA) affects over 15% of the general population and is associated with a higher prevalence of T2D. Growing evidence also indicates that OSA is highly prevalent in T2D patients probably due to diabetic peripheral neuropathy. However, the interrelations among diabetic peripheral neuropathy, OSA, and T2D hitherto have not been clearly elucidated. Numerous molecular mechanisms have been documented that underlie diabetic peripheral neuropathy and OSA, including oxidative stress, inflammation, endothelin-1, vascular endothelial growth factor (VEGF), accumulation of advanced glycation end products, protein kinase C (PKC) signaling, poly ADP ribose polymerase (PARP), nitrosative stress, plasminogen activator inhibitor-1, and vitamin D deficiency. In this review, we seek to illuminate the relationships among T2D, diabetic peripheral neuropathy, and OSA and how they interact with one another. In addition, we summarize and explain the shared molecular mechanisms involved in diabetic peripheral neuropathy and OSA for further mechanistic investigations and novel therapeutic strategies for attenuating and preventing the development and progression of diabetic peripheral neuropathy and OSA in T2D.

Effect of transoral endoscopic adenoidectomy on peripheral blood T-lymphocyte subsets in children with obstructive sleep apnea-hypopnea syndrome and its treatment strategy

The objective of the present study was to investigate the effect of transoral endoscopic adenoidectomy on peripheral blood T lymphocyte subsets in pediatric patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) and its treatment strategy. Ninety-eight pediatric patients with adenoidal hypertrophy associated with OSAHS admitted to the Department of Otolaryngology, Xuzhou Children's Hospital were selected. After admission, patients received perfected 24 h polysomnogram monitoring, routine blood examination, fasting blood biochemistry examination, T-lymphocyte subset count, 24 h ambulatory blood pressure monitoring, and nasopharyngeal computed tomography. After patients were diagnosed with adenoidal hypertrophy associated with OSAHS, they underwent transoral endoscopic adenoidectomy with a power microdebrider. Patients were evaluated at 3-, 6- and 12-week follow-up visits. The CD3⁺, CD4⁺, and CD8⁺ T-cell counts, CD4⁺/CD8⁺ T lymphocyte ratio, and changes of 24 h ambulatory blood pressure before and after surgery were recorded. After the 6-week follow-up visit, the mean CD4⁺ T lymphocyte count in patients was increased significantly compared with that before surgery, the CD4⁺/CD8⁺ T lymphocyte ratio increased gradually, and the differences were statistically significant (P<0.05). The frequency of nocturnal awakening of patients was decreased significantly after surgery and the duration of nocturnal sleep was extended significantly (P<0.05). Through analysis of the preoperative and postoperative clinical data of pediatric patients, the CD4⁺/CD8⁺ T lymphocyte ratio was negatively correlated with mean arterial pressure (MAP) (r=-1.06, P=0.003). In conclusion, adenoidectomy can significantly decrease the MAP in pediatric patients with OSAHS and increase the duration of nocturnal sleep. The peripheral blood CD4⁺/CD8⁺ T lymphocyte ratio in pediatric patients was significantly negatively correlated with MAP.

Effect of Continuous Positive Airway Pressure on Glycemic Control in Patients with Obstructive Sleep Apnea and Type 2 Diabetes. A Randomized Clinical Trial

RATIONALE

Obstructive sleep apnea (OSA) is a risk factor for type 2 diabetes that adversely impacts glycemic control. However, there is little evidence about the effect of continuous positive airway pressure (CPAP) on glycemic control in patients with diabetes.

OBJECTIVES

To assess the effect of CPAP on glycated hemoglobin (HbA1c) levels in patients with suboptimally controlled type 2 diabetes and OSA, and to identify its determinants.

METHODS

In a 6-month, open-label, parallel, and randomized clinical trial, 50 patients with OSA and type 2 diabetes and two HbA1c levels equal to or exceeding 6.5% were randomized to CPAP (n = 26) or no CPAP (control; n = 24), while their usual medication for diabetes remained unchanged.

MEASUREMENTS AND MAIN RESULTS

HbA1c levels, Homeostasis Model Assessment and Qualitative Insulin Sensitivity Check Index scores, systemic biomarkers, and health-related quality of life were measured at 3 and 6 months. After 6 months, the CPAP group achieved a greater decrease in HbA1c levels compared with the control group. Insulin resistance and sensitivity measurements (in noninsulin users) and serum levels of IL-1β, IL-6, and adiponectin also improved in the CPAP group compared with the control group after 6 months. In patients treated with CPAP, mean nocturnal oxygen saturation and baseline IL-1β were independently related to the 6-month change in HbA1c levels (r(2) = 0.510, P = 0.002).

CONCLUSIONS

Among patients with suboptimally controlled type 2 diabetes and OSA, CPAP treatment for 6 months resulted in improved glycemic control and insulin resistance compared with results for a control group. Clinical trial registered with www.clinicaltrials.gov (NCT01801150).

HbA1c levels are associated with severity of hypoxemia and not with apnea hypopnea index in patients with type 2 diabetes: Results from a cross-sectional study

BACKGROUND

The aim of the present study was to evaluate the effect of untreated sleep apnea syndrome (SAS) on glycemic control, evaluated by HbA1c, in patients with type 2 diabetes (T2D).

METHODS

The study sample consisted of 100 consecutive adult (≥18 years) patients with T2D without a prior diagnosis of sleep apnea recruited from an outpatient diabetes clinic. All patients underwent an in-hospital cardiorespiratory study using a three-channel portable sleep diagnostic tool; 64 were found to have sleep apnea, 36 were not. Information on medical history, body weight, height, sleep apnea symptoms, Epworth Sleepiness Scale scores, and HbA1c and fasting plasma glucose levels were recorded.

RESULTS

After adjusting for factors known to affect HbA1c (gender, age, diabetes duration, diabetes treatment, body mass index [BMI], and waist circumference), HbA1c was higher in patients with than without SAS (8.4 % vs 7.6 %, respectively; P = 0.04). A positive correlation was found between the presence of sleep apnea and HbA1c (r = 0.24; P = 0.02). After adjusting for confounding factors (including BMI), only mean and lowest O₂ saturation during sleep were significantly associated with HbA1c (β = -0.23 [P = 0.03] and β = -0.24 [P = 0.007], respectively). After further adjusting for waist circumference, only lowest O₂ saturation during recording remained independently associated with HbA1c (β = -0.21; P = 0.05).

CONCLUSIONS

The presence of sleep apnea is associated with poorer glycemic control in patients with T2D. In patients with sleep apnea and T2D, greater levels of oxygen desaturation are associated with poorer glycemic control.

Obstructive Sleep Apnea and Diabetes: A State of the Art Review

OSA is a chronic treatable sleep disorder and a frequent comorbidity in patients with type 2 diabetes. Cardinal features of OSA, including intermittent hypoxemia and sleep fragmentation, have been linked to abnormal glucose metabolism in laboratory-based experiments. OSA has also been linked to the development of incident type 2 diabetes. The relationship between OSA and type 2 diabetes may be bidirectional in nature given that diabetic neuropathy can affect central control of respiration and upper airway neural reflexes, promoting sleep-disordered breathing. Despite the strong association between OSA and type 2 diabetes, the effect of treatment with CPAP on markers of glucose metabolism has been conflicting. Variability with CPAP adherence may be one of the key factors behind these conflicting results. Finally, accumulating data suggest an association between OSA and type 1 diabetes as well as gestational diabetes. This review explores the role of OSA in the pathogenesis of type 2 diabetes, glucose metabolism dysregulation, and the impact of OSA treatment on glucose metabolism. The association between OSA and diabetic complications as well as gestational diabetes is also reviewed.

Prevalence and Associations of Obstructive Sleep Apnea in South Asians and White Europeans with Type 2 Diabetes: A Cross-Sectional Study

STUDY OBJECTIVES

To assess and compare obstructive sleep apnea (OSA) prevalence in South Asians and White Europeans with type 2 diabetes mellitus (T2DM). Secondary aims included exploring possible causes for observed ethnic differences.

METHODS

A cross-sectional study of patients with T2DM recruited from secondary care diabetes clinics. OSA was defined as an apnea-hypopnea index (AHI) ≥ 5 events/h using home-based, multi-channel respiratory monitoring.

RESULTS

Two hundred thirty-four patients (105 South Asian and 129 White Europeans) were studied. The prevalence of mild, moderate, and severe OSA in South Asians was 36.2% (n = 38/105), 9.5% (n = 10/105), and 5.7% (n = 6/105) respectively. After adjustment, OSA was associated with a higher body mass index in South Asians. OSA was significantly less common in South Asians compared to White Europeans (51.4% [54/105] versus 75.2% [97/129], P < .001). OSA was also less severe in South Asians compared to White Europeans (median [interquartile range]: AHI 5.1 [1.4-11.5] versus 8.5 [5.0-20.7] events/h, P < .001; time spent with oxygen saturations < 90% 0.5 [0.0-2.9]% versus 4.0 [0.7-14.4]%, P < .001). Logistic regression showed that only obesity measures explained the ethnic differences in OSA.

CONCLUSIONS

South Asians with T2DM are at considerable risk of OSA. OSA in South Asians was associated with obesity. However, OSA prevalence was lower in South Asians than in White Europeans. Obesity measures accounted for the observed ethnic differences. Examining factors contributing to ethnic differences will be important to inform screening and treatment strategies.

Associations between nocturnal urinary 6-sulfatoxymelatonin, obstructive sleep apnea severity and glycemic control in type 2 diabetes

Reduced nocturnal secretion of melatonin, a pineal hormone under circadian control, and obstructive sleep apnea have been both identified as risk factors for the development of type 2 diabetes mellitus. Whether they interact to impact glycemic control in patients with existing type 2 diabetes is not known. Therefore, this study explores the relationships between obstructive sleep apnea, melatonin and glycemic control in type 2 diabetes. As diabetic retinopathy may affect melatonin secretion, we also explore the relationship between retinopathy, melatonin and glycemic control. Fifty-six non-shift workers with type 2 diabetes, who were not using beta-blockers, participated. Most recent hemoglobin A1c (HbA1c) levels and the results of ophthalmologic examinations were obtained from medical records. Obstructive sleep apnea was diagnosed using an ambulatory device. Sleep duration and fragmentation were recorded by 7-day wrist actigraphy. The urinary 6-sulfatoxymelatonin/creatinine ratio, an indicator of nocturnal melatonin secretion, was measured in an overnight urine sample. Mediation analyses were applied to explore whether low nocturnal urinary 6-sulfatoxymelatonin/creatinine ratio could be a causal link between increasing obstructive sleep apnea severity [as measured by an Apnea Hypopnea Index (AHI)] and poorer glycemic control, and between the presence of retinopathy and glycemic control. AHI and HbA1c were log-scale (ln) transformed. Obstructive sleep apnea was found in 76.8%, and 25.5% had diabetic retinopathy. The median (interquartile range) of urinary 6-sulfatoxymelatonin/creatinine ratio was 12.3 (6.0, 20.1) ng/mg. Higher lnHbA1c significantly correlated with lower 6-sulfatoxymelatonin/creatinine ratio (p = 0.04) but was not directly associated with OSA severity. More severe obstructive sleep apnea (lnAHI, p = 0.01), longer diabetes duration (p = 0.02), retinopathy (p = 0.01) and insulin use (p = 0.03) correlated with lower urinary 6-sulfatoxymelatonin/creatinine ratio, while habitual sleep duration and fragmentation did not. A mediation analysis revealed that lnAHI negatively correlated with urinary 6-sulfatoxymelatonin/creatinine ratio (coefficient = -2.413, p = 0.03), and urinary 6-sulfatoxymelatonin/creatinine negatively associated with lnHbA1c (coefficient = -0.005, p = 0.02), after adjusting for covariates. Mediation analysis indicated that the effect of lnAHI on lnHbA1c was indirectly mediated by urinary 6-sulfatoxymelatonin/creatinine ratio (B = 0.013, 95% CI: 0.0006, 0.0505). In addition, having retinopathy was significantly associated with reduced nocturnal urinary 6-sulfatoxymelatonin/creatinine ratio, and an increase in HbA1c by 1.013% of its original value (B = -0.013, 95% CI: -0.038, -0.005). In conclusion, the presence and severity of obstructive sleep apnea as well as the presence of diabetic retinopathy were associated with lower nocturnal melatonin secretion, with an indirect adverse effect on glycemic control. Intervention studies are needed to determine whether melatonin supplementation may be beneficial in type 2 diabetes patients with obstructive sleep apnea.

Circadian rhythms and metabolism: from the brain to the gut and back again

This paper focuses on the relationship between the circadian system and glucose metabolism. Research across the translational spectrum confirms the importance of the circadian system for glucose metabolism and offers promising clues as to when and why these systems go awry. In particular, basic research has started to clarify the molecular and genetic mechanisms through which the circadian system regulates metabolism. The study of human behavior, especially in the context of psychiatric disorders, such as bipolar disorder and major depression, forces us to see how inextricably linked mental health and metabolic health are. We also emphasize the remarkable opportunities for advancing circadian science through big data and advanced analytics. Advances in circadian research have translated into environmental and pharmacological interventions with tremendous therapeutic potential.

The association of obstructive sleep apnea (OSA) and nocturnal hypoxemia with the development of abnormal HbA1c in a population cohort of men without diabetes

AIM

To examine the relationship between indices of undiagnosed OSA and the development of abnormal glycaemic control in community-dwelling men free of diabetes.

METHODS

The Men, Androgens, Inflammation, Lifestyle, Environment, and Stress (MAILES) Study is a population-based cohort study in Adelaide, South Australia. Clinic visits at baseline (2002-06) and follow-up (2007-10) identified abnormal glycaemic metabolism [HbA1c 6.0 to <6.5% (42 to <48mmol/mol)] in men without diabetes. At follow-up (2010-11), n=837 underwent assessment of OSA by full in-home unattended polysomnography (Embletta X100).

RESULTS

Development of abnormal glycaemic metabolism over 4-6 years (n=103 "incident" cases, 17.0%) showed adjusted associations [odds ratio (95% CI)] with the 1st [1.7 (0.8-3.8)], 2nd [2.4 (1.1-4.9)], and 3rd [2.3 (1.1-4.8)] quartiles of mean oxygen saturation (SaO2) compared to the highest quartile. Prevalent abnormal glycaemic metabolism (n=140, 20.8%) was independently associated with the third and fourth quartiles of percentage of sleep time with oxygen saturation <90% and lowest quartile of mean SaO2. Linear regression analysis showed a significant reduction in HbA1c [unstandardized B, 95% CI: -0.02 (-0.04, -0.002), p=0.034] per percentage point increase in mean SaO2. OSA as measured by the apnea-hypopnea index showed no adjusted relationship with abnormal glycaemic metabolism.

CONCLUSIONS

Development of abnormal glycaemic metabolism was associated with nocturnal hypoxemia. Improved management of OSA and glycaemic control may occur if patients presenting with one abnormality are assessed for the other.

Sleep Apnea in Type 2 Diabetes

IN BRIEF Obstructive sleep apnea (OSA) alters glucose metabolism, promotes insulin resistance, and is associated with development of type 2 diabetes. Obesity is a key moderator of the effect of OSA on type 2 diabetes. However, chronic exposure to intermittent hypoxia and other pathophysiological effects of OSA affect glucose metabolism directly, and treatment of OSA can improve glucose homeostasis.

Intermittent hypoxia is an independent marker of poorer glycaemic control in patients with uncontrolled type 2 diabetes

AIM

This study investigated the association between intermittent hypoxia and glycaemic control in patients with uncontrolled type 2 diabetes (T2D) not treated for sleep apnoea.

METHODS

This was a single-centre cross-sectional study of stable patients with T2D and HbA1c ≥7% (53 mmol/mol). Patients underwent overnight pulse oximetry and, if intermittent hypoxia-defined by a 4% oxyhaemoglobin desaturation index ≥15-was observed, respiratory polygraphy was performed. All participants completed the Pittsburgh Sleep Questionnaire and Hospital Anxiety and Depression Scale. The association between intermittent hypoxia and poorer glycaemic control (defined by an HbA1c level above the median of 8.5%) was estimated by multivariate logistic regression analysis.

RESULTS

Out of 145 patients studied, 54 (37.2%) had intermittent hypoxia (with sleep apnoea confirmed in 53). Patients with intermittent hypoxia had 0.7% (7.7 mmol/mol) higher median HbA1c levels than patients without intermittent hypoxia (P=0.001). Intermittent hypoxia was associated with poorer glycaemic control after adjusting for obesity, age at onset and duration of diabetes, insulin requirement, sleep quality and depressive mood (OR: 2.31, 95% CI: 1.06-5.04, model adjusted for body mass index; OR: 2.46, 95% CI: 1.13-5.34, model adjusted for waist-to-height ratio).

CONCLUSION

Intermittent hypoxia, a consequence of sleep apnoea, is frequent and has a strong independent association with poorer glycaemic control in patients with uncontrolled T2D.

Comparative effectiveness research in obstructive sleep apnea: bridging gaps between efficacy studies and clinical practice

Comparative effectiveness research encompasses research that compares two interventions to each other, and takes place in real-world settings without strict inclusion and exclusion criteria, according to the established standard of care. There is a need for comparative evaluations of the treatments for obstructive sleep apnea, a disease associated with increased cardiovascular risk, stroke and metabolic derangement. This article reviews the recent, representative literature that addresses obstructive sleep apnea intervention and treatment, paradigms for diagnosis and randomized control trials addressing the efficacy of interventions, in an effort to demonstrate examples of both traditional observational and randomized control trials, as well as to illustrate the considerable overlap between some traditional studies and comparative effectiveness research. Despite methodological challenges, the potentially large clinical and public health impact of obstructive sleep apnea, accompanied by considerable cost, mandates that randomized controlled trials and comparative effectiveness research be systematically applied to identify both the efficacy and effectiveness of alternative diagnosis and treatment strategies.

New frontiers in obstructive sleep apnoea

OSA (obstructive sleep apnoea), the most common respiratory disorder of sleep, is caused by the loss of upper airway dilating muscle activity during sleep superimposed on a narrow upper airway. This results in recurrent nocturnal asphyxia. Termination of these events usually requires arousal from sleep and results in sleep fragmentation and hypoxaemia, which leads to poor quality sleep, excessive daytime sleepiness, reduced quality of life and numerous other serious health consequences. Furthermore, patients with untreated sleep apnoea are at an increased risk of hypertension, stroke, heart failure and atrial fibrillation. Although there are many predisposing risk factors for OSA, including male gender, endocrine disorders, use of muscle relaxants, smoking, fluid retention and increased age, the strongest risk factor is obesity. The aim of the present review is to focus on three cutting-edge topics with respect to OSA. The section on animal models covers various strategies used to simulate the physiology or the effects of OSA in animals, and how these have helped to understand some of the underlying mechanisms of OSA. The section on diabetes discusses current evidence in both humans and animal models demonstrating that intermittent hypoxia and sleep fragmentation has a negative impact on glucose tolerance. Finally, the section on cardiovascular biomarkers reviews the evidence supporting the use of these biomarkers to both measure some of the negative consequences of OSA, as well as the potential benefits of OSA therapies.

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.

Associations of Alcohol Consumption and Chronic Diseases With Sleep Apnea Among US Adults

BACKGROUND

Sleep apnea (SA) is a common sleep disorder among US adults. Associations of SA with alcohol consumption and some chronic diseases have been inconsistent.

OBJECTIVES

This study aimed to estimate prevalence of SA and examine its associations with potential factors including alcohol consumption, asthma, diabetes, and hypertension.

PATIENTS AND METHODS

This was a cross-sectional study on 823 adults with SA and 38,638 controls from the 2011 National Survey on Drug Use and Health Data. Weighted univariate and multiple logistic regression analyses were used to examine the associations of SA with the potential factors.

RESULTS

The prevalence of SA was higher in males (4.01%) than in females (2.61%), while the prevalence increased with age (0.86%, 3.50%, and 4.47% for age groups of 18-25, 26-64, and ≥ 65, respectively). Univariate analysis revealed that all factors except for income and education were associated with SA (P < 0.05). In multivariable analyses, participants who were current and past alcohol consumers had significantly higher odds of having SA (OR = 1.52, 95% CI = 1.03-2.23; OR = 1.65, 95% CI = 1.09-2.49, respectively) than non-alcohol drinker. Furthermore, asthma (OR = 2.77, 95% CI = 2.04-3.75), diabetes (OR = 2.89, 95% CI = 2.19-3.83), and hypertension (OR = 2.42, 95% CI = 1.91-3.07) were significantly associated with SA.

CONCLUSIONS

Age, alcohol consumption, asthma, diabetes, and hypertension, were positively associated with SA. More efforts should be directed to promoting screening for SA and finding possible treatments for SA among these vulnerable groups.

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.

Interactions between sleep, circadian function, and glucose metabolism: implications for risk and severity of diabetes

Sleep disturbances, including sleep insufficiency and sleep fragmentation, have been linked to abnormal glucose metabolism and increased diabetes risk. Well-controlled laboratory studies have provided insights regarding the underlying mechanisms. Several large prospective studies suggest that these sleep disturbances are associated with an increased risk of incident diabetes. Obstructive sleep apnea, which combines sleep fragmentation and hypoxemia, is a major risk factor for insulin resistance and possibly diabetes. Whether glycemic control in type 2 diabetes patients can be improved by treating sleep apnea remains controversial. Recently, sleep disturbances during pregnancy and their relationship to gestational diabetes and hyperglycemia have received considerable attention owing to potential adverse effects on maternal and fetal health. Additionally, evidence from animal models has identified disruption of the circadian system as a putative risk factor for adverse metabolic outcomes. The purpose of this review is to provide an update on the current state of knowledge linking sleep disturbances, circadian dysfunction, and glucose metabolism. Experimental, prospective, and interventional studies are discussed.

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.

Association of obstructive sleep apnea in rapid eye movement sleep with reduced glycemic control in type 2 diabetes: therapeutic implications

OBJECTIVE

Severity of obstructive sleep apnea (OSA) has been associated with poorer glycemic control in type 2 diabetes. It is not known whether obstructive events during rapid eye movement (REM) sleep have a different metabolic impact compared with those during non-REM (NREM) sleep. Treatment of OSA is often limited to the first half of the night, when NREM rather than REM sleep predominates. We aimed to quantify the impact of OSA in REM versus NREM sleep on hemoglobin A1c (HbA1c) in subjects with type 2 diabetes.

RESEARCH DESIGN AND METHODS

All participants underwent polysomnography, and glycemic control was assessed by HbA1c.

RESULTS

Our analytic cohort included 115 subjects (65 women; age 55.2 ± 9.8 years; BMI 34.5 ± 7.5 kg/m(2)). In a multivariate linear regression model, REM apnea-hypopnea index (AHI) was independently associated with increasing levels of HbA1c (P = 0.008). In contrast, NREM AHI was not associated with HbA1c (P = 0.762). The mean adjusted HbA1c increased from 6.3% in subjects in the lowest quartile of REM AHI to 7.3% in subjects in the highest quartile of REM AHI (P = 0.044 for linear trend). Our model predicts that 4 h of continuous positive airway pressure (CPAP) use would leave 60% of REM sleep untreated and would be associated with a decrease in HbA1c by approximately 0.25%. In contrast, 7 h of CPAP use would cover more than 85% of REM sleep and would be associated with a decrease in HbA1c by as much as 1%.

CONCLUSIONS

In type 2 diabetes, OSA during REM sleep may influence long-term glycemic control. The metabolic benefits of CPAP therapy may not be achieved with the typical adherence of 4 h per night.

Use of a level 3 portable monitor for the diagnosis and management of sleep disordered breathing in an inpatient tertiary care setting

BACKGROUND

Sleep-disordered breathing (SDB) may impact the course of medical illness among hospitalized patients. Access to testing during hospitalization to assess this may be limited by wait times for laboratory polysomnography. Level 3 portable monitoring (PM) may provide an alternative.

OBJECTIVE

To assess the rate of technically adequate studies, diagnostic information obtained and impact on patient management of inpatient PM studies performed for SDB.

METHODS

A retrospective review of 114 PM (Embletta, Natus Inc, Canada) records from the past two years was performed. Studies were ordered by pulmonologists, initiated by respiratory therapists and performed unattended on inpatient units. Admitting diagnoses, indication for sleep study, diagnostic information obtained from recordings and change in clinical management subsequent to PM were determined from medical charts.

RESULTS

Of 114 studies reviewed, 99 (87%) met predetermined criteria for adequate signal quality and duration. Five studies could not be interpreted due to inadequate data, yielding an overall success rate of 83% (94 of 114). Of 86 studies performed for diagnosis, clinical and PM data supported a new diagnosis of SDB in 55 patients, of which 23 (42%) were started on positive pressure therapy. Thirteen PM studies were performed during SDB treatment. All were technically adequate and six of 13 demonstrated new or persistent SDB. Results from PM testing informed clinical management during hospitalization in 70 (61%) cases.

CONCLUSION

Unattended level 3 PM studies are technically feasible in hospitalized patients and may provide information that influences clinical management.

Obstructive sleep apnea in children: a critical update

Obstructive sleep apnea (OSA) in children is a highly prevalent disorder caused by a conglomeration of complex pathophysiological processes, leading to recurrent upper airway dysfunction during sleep. The clinical relevance of OSA resides in its association with significant morbidities that affect the cardiovascular, neurocognitive, and metabolic systems. The American Academy of Pediatrics recently reiterated its recommendations that children with symptoms and signs suggestive of OSA should be investigated with polysomnography (PSG), and treated accordingly. However, treatment decisions should not only be guided by PSG results, but should also integrate the magnitude of symptoms and the presence or absence of risk factors and signs of OSA morbidity. The first-line therapy in children with adenotonsillar hypertrophy is adenotonsillectomy, although there is increasing evidence that medical therapy, in the form of intranasal steroids or montelukast, may be considered in mild OSA. In this review, we delineate the major concepts regarding the pathophysiology of OSA, its morbidity, diagnosis, and treatment.

Sleep apnoea syndrome and 10-year cardiovascular risk in females with type 2 diabetes: relationship with insulin secretion and insulin resistance

BACKGROUND

Obstructive sleep apnoea syndrome (OSAS) is a risk factor for type 2 diabetes mellitus (T2DM) and promotes cardiovascular events, especially in men. The prevalence of sleep apnoea and its association with microvascular and macrovascular diseases and glycaemic control are poorly documented in T2DM women.

METHODS

A total of 305 T2DM women were sleep apnoea diagnosed through (hetero)anamnesis, Epworth's score, oximetry and polysomnography. Sleep apnoea[+] (n = 25) were compared with sleep apnoea[-] (n = 280) regarding cardiovascular risk factors, glucose homeostasis, micro/macrovascular complications and the United Kingdom Prospective Diabetes Study (UKPDS) 10-year risk.

RESULTS

Mean (1 SD) age was 66 (12) years, diabetes duration 15 (9) years, sleep apnoea prevalence 8.2% and metabolic syndrome 86%. There were no differences in age, diabetes duration, education, smoking and blood pressure between groups. Sleep apnoea[+] had significantly higher values of body mass index, waist, relative/absolute fat, conicity, visceral fat (all p < 0.0001) and lower skeletal muscle (p = 0.0008). The sleep apnoea[+] group was more insulin resistant [homeostasis model assessment (HOMA S): 37 (20)% versus 59 (44)%; p < 0.0001] and had lesser residual insulin secretion (HOMA B × S: 20 (12)% versus 30 (19)%; p = 0.0006), increased hyperbolic product loss (p = 0.0442) and poorer glycaemic control (HbA1c 69 (12) versus 62 (13) mmol mol(-1) ; p = 0.0099). All atherogenic dyslipidaemia components and inflammatory markers were worsened in sleep apnoea[+]. Women with sleep apnoea had higher UKPDS risk of CAD: 18 (11)% versus 12 (10)% (p = 0.0136). Prevalent micro/macrovascular complications were not different between groups.

CONCLUSIONS

Sleep apnoea, a frequent comorbidity of T2DM women, is associated with central fat, atherogenic dyslipidaemia, inflammation, worsening β-cell function, poorer glycaemic control and coronary artery disease risk. Sleep apnoea may increase residual vascular risk for microvascular and macrovascular events in T2DM women.

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.

Obesity prevention and intervention in dental practice

Dentists have an important role in preventing and detecting oral and systemic diseases because of their diagnostic and screening abilities and the frequency of patient visits. These skills and practice paradigms should be considered in solving the obesity epidemic. The well-described connection between periodontal disease and diabetes is a reason for dentists to intervene in the rise of obesity. Dentists are in a unique position to identify and aid in treatment of obstructive sleep apnea, a condition associated with obesity and diabetes. Dentists can play a role in raising awareness of overweight status and obesity risk behaviors in children.

Obstructive sleep apnea and type 2 diabetes: is there a link?

Type 2 diabetes is a chronic illness that is increasing in epidemic proportions worldwide. Major factors contributing to the development of type 2 diabetes include obesity and poor lifestyle habits (e.g., excess dietary intake and limited physical activity). Despite the proven efficacy of lifestyle interventions and the use of multiple pharmacological agents, the economic and public health burden of type 2 diabetes remains substantial. Obstructive sleep apnea (OSA) is a treatable sleep disorder that is pervasive among overweight and obese adults, who represent about two thirds of the U.S. population today. An ever-growing number of studies have shown that OSA is associated with insulin resistance, glucose intolerance and type 2 diabetes, independent of obesity. Evidence from animal and human models that mimic OSA provides potential mechanisms for how OSA may alter glucose metabolism. Up to 83% of patients with type 2 diabetes suffer from unrecognized OSA and increasing severity of OSA is associated with worsening glucose control. However, it is still unclear whether OSA may lead to the development of diabetes over time. More data from large-scale longitudinal studies with rigorous assessments of diabetes and OSA are needed. In addition, there is still controversy whether continuous positive airway pressure (CPAP) treatment of OSA improves glucose metabolism. Large-scale randomized-controlled trials of CPAP treatment of OSA with well-validated assessments of insulin sensitivity and glucose tolerance are needed. These studies may reveal that OSA represents a novel, modifiable risk factor for the development of prediabetes and type 2 diabetes.