The impact of obstructive sleep apnoea in extreme obesity : the impact on ethnicity, glycaemia and diabetes related microvascular complications

Obesity is known to be associated with obstructive sleep apnoea (OSA) and Type 2 diabetes mellitus (T2DM). The effect of OSA in very severely obese individuals is not well documented. In this thesis, I compared the effect of OSA in South Asians and white Europeans, examined the effect of OSA on glycaemic control among T2DM, and explored the relationship between OSA and diabetic retinal and kidney diseases in a severely obese population. I also systematically reviewed the effect of OSA on diabetic kidney and retinal diseases. Findings from this thesis were 1) severely obese South Asians had greater severity of OSA compared to white Europeans and the mechanisms mediating this require further investigation, 2) a high OSA prevalence in T2DM individuals with a positive relationship between nocturnal hypoxia and glycaemic control, 3) severity of hypoxaemia during sleep may be an important factor in the development of diabetic retinal complications, 4) duration of hypoxaemia during sleep were inversely associated with renal function in T2DM and 5) from the systematic review, there is a need for future large cohort studies with long term follow-up data to examine the long-term effects of OSA and other sleep parameters on diabetic retinal and kidney diseases.