Original articleCPAP treatment does not affect glucose–insulin metabolism in sleep apneic patients
Introduction
Obstructive sleep apnea is a common problem in the general population. Young et al. [1] studied a well-selected sample of 602 middle-aged patients (30–60 years old) and found that 24% of the men and 9% of the women had an apnea-hypopnea index >5 events/h of sleep. They estimated that 2% of women and 4% of men in the middle age work force meet the minimal diagnostic criteria for the sleep apnea syndrome (≥5 apnea-hypopnea events/ h of sleep and daytime hypersomnolence).
There are controversies surrounding the effects of obstructive sleep apnea and the repetitive short drops of oxygen saturation associated with the abnormal respiratory events on nocturnal glucose metabolism.
Previous studies [2], [3] have shown a relationship between glucose intolerance and obstructive sleep apnea syndrome (OSAS). High blood pressure, stroke and myocardial infarction have been associated with obstructive sleep apnea syndrome but also with insulin resistance [4], [5], [6]. The proposed mechanisms for the association between sleep disordered breathing and abnormal glucose metabolism included: presence of abnormal sympathetic activation, well demonstrated in OSAS patients [7], [8]; secondary development of atherosclerosis; and reduced endothelium-dependent vascular relaxation [9], [10]. Repetitive hypoxemia, with sympathetic activation and catecholamine release, contribute to insulin resistance [11], [12]. Based on these findings in obese OSA subjects, the possibility that abnormal breathing during sleep could be responsible for metabolic changes, and more particularly glucose intolerance and insulin resistance was considered [2], [3], [13]. Stoohs et al. [14], however, have argued against this position. Obesity is an important confounding variable, as it is associated with glucose intolerance and insulin resistance. Exclusion of clearly obese subjects when investigating the role of OSAS is one way to avoid the problems. Another strategy is to treat adequately the sleep apnea syndrome and to investigate any changes in glucose metabolism.
We designed a protocol that combined both approaches. We recruited non-obese or moderately overweight subjects with OSAS, including some with and some without glucose intolerance, and we investigated both subgroups at baseline and after 2 months of nasal CPAP treatment, with good nocturnal compliance.
Section snippets
Subjects
We recruited our subjects from the patient population consulting the endocrinology department at the University Hospital of Bordeaux. As part of their routine evaluation, all subjects had to complete a sleep questionnaire and undergo a clinical interview that included a sleep disorders evaluation. The sleep questionnaire included questions about snoring (frequency, loudness), observations by bed partners of abnormal breathing events during sleep and complaints of daytime tiredness and/or
For the ten subjects first recruited
The mean CPAP pressure was 6.4±1.08 cm H2O. Compared to baseline, during the night of CPAP titration, stage 1–2 decreased (ns), slow wave sleep increased (ns) as did REM sleep (ns). A significant augmentation trend was observed in sleep efficiency (P<0.02). The mean AHI significantly decreased (P<0.05) during the night of CPAP titration (from 31.06 to 3.1 events/h of sleep). The mean CPAP usage was 6.4±0.8 h/ day.
For the six matched OSAS patients
The mean CPAP pressure prescribed was 7.16±1.47 cm H2O. On the night of monitored
Discussion
The main goal of this study was to determine if a relationship between sleep, disordered breathing and glucose metabolism could be demonstrated. In order to limit bias factors regarding glucose metabolism, all our subjects came from a population of non-obese or moderately obese subjects. We carefully excluded patients with family history of diabetes [22], renal failure [23], hepatic insufficiency [24] or consumption of drugs interfering with glucose metabolism [25], such as beta blockers or
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Continuous positive airway pressure and diabetes risk in sleep apnea patients: A systemic review and meta-analysis
2017, European Journal of Internal MedicineCitation Excerpt :However, prior studies investigating whether CPAP can improve insulin resistance of glucose control in OSA patients have resulted in conflicting findings. Some work found CPAP treatment resulted in a significant reduction in HbA1c and improvement in glycemic control [13,14,19–21], while other studies found no effect of CPAP on diabetes-related outcomes [22–26]. Similarly, some but not all studies, found CPAP therapy improved insulin sensitivity [14,19,21–23,26–28].
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