Screening for sleep apnea may be useful in a number of settings, such as preoperative testing, clinical research, and evaluation for referral to a sleep center. The purpose of the study was to validate the ApneaLink device (ResMed Corporation, Poway, Calif) for use as a screening tool for sleep apnea in clinical practice. The ApneaLink device is a single-channel screening tool for sleep apnea that measures airflow through a nasal cannula connected to a pressure transducer, providing an apnea-hypopnea index (AHI) based on recording time. We compared the AHI from the ApneaLink device to that obtained during simultaneously conducted attended sleep-laboratory polysomnography to assess the sensitivity and specificity of the device in consecutive subjects with type 2 diabetes mellitus referred from a diabetes clinic. We also compared the AHI obtained from the ApneaLink device during a study in the subjects' homes to that obtained during the in-laboratory study. The laboratory study was performed within 2 weeks of the home study. Fifty-nine subjects completed the study. Mean age of subjects was 57 years; mean body mass index was 33 kg/m2. The results demonstrate a high sensitivity and specificity of the at-home ApneaLink AHI compared with the AHI from the simultaneous polysomnographic study at all AHI levels, with the best results at an AHI of > or =15 events per hour (sensitivity 91%, specificity 95%). The AHI comparison from the home and laboratory studies also demonstrates good sensitivity and specificity at AHI levels of > or =15 and > or =20 events per hour (sensitivity 76%, specificity 94%, for both). Given the prevalence of sleep apnea in the adult population and in specific comorbid conditions, a screening tool may be useful in many diagnostic settings. This study demonstrates that the ApneaLink device provides reliable information, is a simple, easy-to-use device, and is highly sensitive and specific in calculating AHI, when compared with the AHI obtained from full polysomnography.