 Obstructive sleep apnoea OSA has been reported to be common 17 in patients with diabetes mellitus DM. Both OSA and DM are highly associated with cardiovascular morbidity and mortality. There is growing evidence that OSA may trigger or worsen pre-existing adverse metabolic profile indicative of cardiovascular risk. Treatment of OSA with nasal Continuous Positive Airway Pressure nCPAP has been shown to reduce blood pressure and hence to reduce the risk of atherogenesis. In patients with DM, the therapeutic effect of nCPAP is still not known, it would be important to delineate any independent effect of OSA on DM and the therapeutic effect of nCPAP on glycemic control to reduce the long term risk of macrovascular and microvascular complications. 