Obstructive Sleep Apnoea Syndrome (OSAS) is a common disorder, characterised by repetitive episodes of partial or complete obstruction of the upper airway during sleep and associated with increasing respiratory efforts. These perturbations lead, in turn, to oxyhaemoglobin desaturation,
sleep fragmentation, and daytime symptoms, mainly excessive
sleepiness. Accumulating evidence suggests that intermittent
hypoxia and oxyhaemoglobin desaturation may result, independently of
obesity, in impaired
glucose metabolism, as well as
insulin resistance even in non-diabetic patients with OSAS. Additionally, OSAS has been proposed as an independent risk factor for
type 2 diabetes mellitus.
Continuous Positive Airway Pressure (CPAP) is the treatment of choice for OSAS, since it eliminates upper airway collapse during sleep and also improves
sleep fragmentation, daytime symptoms and quality of life. Moreover, it has been proposed that the amelioration of breathing disturbances during sleep can improve several markers of
glucose metabolism and
insulin resistance, such as glycated haemoglobin, fasting
glucose,
insulin, and
insulin resistance. Indeed, some studies have reported improvements in these parameters especially in compliant patients. However, other works failed to confirm this beneficial effect. The present article reviews the issue whether CPAP treatment exerts a beneficial effect on
glucose metabolism and
insulin resistance.