Screening for diabetes mellitus in patients with OSAS: a case for glycosylated haemoglobin

To the Editors: Obstructive sleep apnoea syndrome (OSAS) is a highly prevalent disorder, associated with decreased quality of life, increased risk of road traffic accidents, and increased cardiovascular morbidity and mortality [1]. OSAS also appears to independently predict metabolic dysfunction, with a growing body of evidence suggesting that sleep disordered breathing may be an independent driver of insulin resistance and dysglycaemia [2]. Indeed, a particularly intimate relationship exists between obesity and the development of OSAS and type 2 diabetes mellitus (T2DM): in the Sleep Heart Health Study over half of the diabetic subjects studied had some degree of sleep disordered breathing, while 23.8% had a respiratory disturbance index in the moderate or severe range [3]. Similarly, up to 40% of subjects with OSAS are diabetic at diagnosis [4]. Identification of subjects with T2DM allows the introduction of appropriate treatment to reduce cardiovascular morbidity and diabetes-related mortality. While screening for T2DM has conventionally utilised either fasting plasma glucose (FPG) measurement or performance of an oral glucose tolerance test (OGTT), glycosylated haemoglobin (HbA1c) measurement has recently been approved as a stand-alone diagnostic …