Obstructive Sleep Apnea Syndrome (osas) Has Been Repeatedly Shown to Be Associated with Impaired Glucose Metabolism, Resulting Main- Ly from Insulin

OBSTRUCTIVE SLEEP APNEA SYNDROME (OSAS) HAS BEEN REPEATEDLY SHOWN TO BE ASSOCIATED WITH IMPAIRED GLUCOSE METABOLISM, RESULTING MAINLY FROM INSULIN RESISTANCE,1-3 and, more recently, OSAS has been linked to the metabolic syndrome.4 However, data on early or late effects of OSAS treatment with continuous positive airway pressure (CPAP) on blood glucose and insulin resistance are conflicting.5-9 We have therefore conducted a study aiming to assess the immediate effect of CPAP on glucose control measured with a continuous glucose monitoring system (CGMS).10 The CGMS is a recently developed electronic system designed to continuously monitor subcutaneous glucose concentration in interstitial fluid. It consists of 4 elements: a subcutaneous glucose sensor, a pager-sized continuous glucose monitor worn on a belt, a cable, and a communication station with software. A disposable sterile 1-cm needle-like glucose sensor is inserted into the subcutaneous tissue 15 to 20 cm laterally from the umbilicus. The glucose sensor records interstitial glucose concentration every 10 seconds and stores an average glucose value for each 5-minute period, thus enabling up to 288 measurements to be made per day. The sensor measures glucose as a potential, created by the chemical reaction in which hydrogen peroxide is formed by glucose oxidase from glucose and oxygen. The sensor requires calibration to be made at least 4 times during each day that the CGMS is used. The sensor is calibrated by entering the blood glucose measurement obtained from a glucose meter into the monitor. The CGMS is designed to record glucose levels for up to 72 hours, and it reliably measures glucose concentrations in the range of 40 to 400 mg/dL.10,11 Within normal glucose values, the correlation coefficient between the CGMS results and the readings on the blood glucose meters have been reported to be between 0.84 and 1.0, and mean absolute error to be from 7% to 17%.11 Boyne et al12 found that in a group of patients with type 1 diabetes who experienced blood glucose levels between 50 and 250 mg/dL, the interstitial glucose may lag behind blood glucose for 4 to 10 minutes, usually when rapid changes in blood glucose occur. This observation, however, is not relevant for persons with normal glucose metabolism who maintain stable blood glucose levels.