BackgroundObstructive sleep apnea (OSA) is a common yet underdiagnosed condition. The aim of our study is to test whether prediabetes and type 2 diabetes are associated with obstructive sleep apnea (OSA) in extremely obese (BMI ≥ 40 kg/m2) subjects.MethodsOne hundred and thirty seven consecutive extremely obese patients (99 females) from a controlled clinical trial [MOBIL-study (Morbid Obesity treatment, Bariatric surgery versus Intensive Lifestyle intervention Study) (ClinicalTrials.gov number NCT00273104)] underwent somnography with Embletta® and a 2-hour oral glucose tolerance test (OGTT). OSA was defined by an apnea-hypopnea index (AHI) ≥ 5 events/hour. Patients were categorized into three groups according to criteria from the American Diabetes Association: normal glucose tolerance, pre-diabetes and type 2 diabetes. Multiple logistic regression analysis was used to identify possible determinants of OSA.ResultsThe patients had a mean (SD) age of 43 (11) years and a body mass index (BMI) of 46.9 (5.7) kg/m2. Males had significantly higher AHI than females, 29 (25) vs 12 (17) events/hour, p < 0.001. OSA was observed in 81% of men and in 55% of women, p = 0.008. Twenty-nine percent of subjects had normal glucose tolerance, 42% had pre-diabetes and 29% had type 2 diabetes. Among the patients with normal glucose tolerance 33% had OSA, while 67% of the pre-diabetic patients and 78% of the type 2 diabetic patients had OSA, p < 0.001. After adjusting for age, gender, BMI, high sensitive CRP and HOMA-IR, both pre-diabetes and type 2 diabetes were still associated with OSA, odds ratios 3.18 (95% CI 1.00, 10.07), p = 0.049 and 4.17 (1.09, 15.88), p = 0.036, respectively. Mean serum leptin was significantly lower in the OSA than in the non-OSA group, while other measures of inflammation did not differ significantly between groups.ConclusionsType 2 diabetes and pre-diabetes are associated with OSA in extremely obese subjects.Trial registrationMOBIL-study (Morbid Obesity treatment, Bariatric surgery versus Intensive Lifestyle intervention Study) (ClinicalTrials.gov number NCT00273104)

I ntroduction: Few studies have compared the effect of surgical and conservative weight loss strategies on obstructive sleep apnea (OSA). We hypothesized that Roux-en-Y gastric bypass (RYGB) would be more effective than intensive lifestyle intervention (ILI) at reducing the prevalence and severity of OSA (apnea-hypopnea-index [AHI] ≥ 5 events/hour). Methods: A total of 133 morbidly obese subjects (93 females) were treated with either a 1-year ILI-program (n = 59) or RYGB (n = 74) and underwent repeated sleep recordings with a portable somnograph (Embletta). Results: Participants had a mean (SD) age of 44.7(10.8) years, BMI 45.1(5.7) kg/m 2 , and AHI 17.1(21.4) events/hour. Eightyfour patients (63%) had OSA. The average weight loss was 8% in the ILI-group and 30% in the RYGB-group (p < 0.001). The mean (95%CI) AHI reduced in both treatment groups, although signifi cantly more in the RYGB-group (AHI change -6.0 [ILI] vs -13.1 [RYGB]), between group difference 7.2 (1.3, 13.0), p = 0.017. Twenty-nine RYGB-patients (66%) had remission of OSA, compared to 16 ILI-patients (40%), p = 0.028. At follow-up, after adjusting for age, gender, and baseline AHI, the RYGB-patients had signifi cantly lower adjusted odds for OSA than the ILI-patients-OR (95% CI) 0.33 (0.14, 0.81), p = 0.015. After further adjustment for BMI change, treatment group difference was no longer statistically signifi cant-OR (95% CI) 1.31 (0.32, 5.35), p = 0.709. Conclusion: Our study demonstrates that RYGB was more effective than ILI at reducing the prevalence and severity of OSA. However, our analysis also suggests that weight loss, rather than the surgical procedure per se, explains the benefi cial effects. S C I E N T I F I C I N V E S T I G A T I O N SO bstructive sleep apnea (OSA) is a commonly unrecognized condition with an especially high prevalence among morbidly obese subjects.1,2 OSA is characterized by apneas and hypopneas due to the collapse of upper airways and is defi ned by ≥ 5 apneas or hypopneas per hour during sleep, as measured by the apnea-hypopnea index (AHI). Mild OSA is defi ned as 5-15 episodes of apneas or hypopneas per hour, moderate OSA 15-30, and severe OSA ≥ 30. A metaanalysis from 2009 concluded that continuous positive airway pressure (CPAP) is a cost-effective treatment of OSA and that it reduces daytime sleepiness compared to placebo or usual care.3 Accordingly, CPAP is the fi rst-line treatment and is recommended for all patients with moderate to severe OSA (AHI ≥ 15). Obesity, older age, male sex, and heredity are well-established risk factors for OSA, 5 with obesity being the single most important modifi able risk factor. In cases of obesity, fat deposits narrow the upper airways, and abdominal fat masses decrease the tracheal tension, both increasing the collapsibility of the upper airways. If untreated, OSA is associated with increased risk of diabetes, cardiovascular disease, driving accidents, and allcause mortality. BRIEF SUMMARYCurrent Knowledge/Study Rationale: Weight reduction reduces the severity of OSA in ...

Obese patients have a high prevalence of obstructive sleep apnoea (OSA), but a low response rate and high frequency of relapse after uvulopalatopharyngoplasty (UVPP). In this study we have determined the level of obstruction during sleep in 31 men with OSA, using a catheter with multiple micropressure transducers and a portable digital recorder. The proportion of apnoeic episodes with obstruction at lower levels correlated with increasing body mass index (BMI) (P < 0.05). Thus, with increasing obesity, there seems to be a shift to a lower level of obstruction. All patients with BMI > 30 and apnoea index (AI) > 5 had predominantly lower obstructions (P < 0.05). This may explain why many obese patients fail to respond, or have relapses after UVPP.

Repeatability of sites of obstructive events is influenced by the severity of illness and the degree of upper or lower obstructive predominance. The distribution of sites of obstructive events (classified as mainly "upper"/"lower" or as percent upper obstructive events of all) can be identified with relative confidence in patients who have frequent apneic events (AI > or = 5) or a high degree of upper or lower obstructive predominance and especially in those who have a combination of these two criteria.

BMI is a simple, yet important predictor of subjective reduction of snoring after LAUP and should be considered before performing such surgery.