An update on obstructive sleep apnea and the metabolic syndrome

Current Opinion in Pulmonary Medicine:Volume 13(6)November 2007p 484-489
An update on obstructive sleep apnea and the metabolic syndrome
[Sleep and respiratory neurobiology: Edited by Lee K. Brown]

Lam, Jamie CM; Ip, Mary SM

University Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Pokfulam, Hong Kong SAR, China

Correspondence to Mary S.M. Ip, MD, University Department of Medicine, Queen Mary Hospital, The University of Hong Kong, 102 Pokfulam Road, Pokfulam, Hong Kong SAR, China Tel: +852 28554455; fax: +852 28162863; e-mail: msmip@hkucc.hku.hk

Abstract
Purpose of review: Patients with obstructive sleep apnea are often overweight or obese, and they frequently exhibit metabolic aberrations, collectively known as the metabolic syndrome, an established cardiovascular risk factor. We review recent data on the relationship between obstructive sleep apnea and metabolic syndrome or its components, including abdominal obesity, insulin resistance, hypertension, and dyslipidemia.

Recent findings: There is accumulating evidence for an independent association between obstructive sleep apnea and metabolic syndrome or its components. Recent epidemiologic and clinical data suggest a causal role of severe obstructive sleep apnea in development of hypertension, but findings for insulin resistance and dyslipidemia are controversial. Visceral obesity remains a confounding issue in analyses. Animal models and translational studies indicate that obstructive sleep apnea may promote metabolic dysfunction through cycles of intermittent hypoxia; proposed underlying pathophysiologic mechanisms include oxidative stress, sympathetic activation, and inflammation.

Summary: There is suggestive evidence, but independent associations between obstructive sleep apnea and metabolic syndrome or its components are not fully established because of the confounding effect of obesity. Large randomized interventional trials are needed to identify any cause-effect relationship. Long-term follow-up studies would help to clarify the role of treatment of sleep apnea in reducing cardio-metabolic morbidity.

© 2007 Lippincott Williams & Wilkins, Inc.