Cholesterol metabolism and weight reduction in subjects with mild obstructive sleep apnoea: a randomised, controlled study

Abstract

To evaluate whether parameters of obstructive sleep apnoea (OSA) associate with cholesterol metabolism before and after weight reduction, 42 middle-aged overweight subjects with mild OSA were randomised to intensive lifestyle intervention (N = 23) or to control group (N = 18) with routine lifestyle counselling only. Cholesterol metabolism was evaluated with serum noncholesterol sterol ratios to cholesterol, surrogate markers of cholesterol absorption (cholestanol and plant sterols) and synthesis (cholestenol, desmosterol, and lathosterol) at baseline and after 1-year intervention. At baseline, arterial oxygen saturation (SaO2 ) was associated with serum campesterol (P < 0.05) and inversely with desmosterol ratios (P < 0.001) independently of gender, BMI, and homeostasis model assessment index of insulin resistance (HOMA-IR). Apnoea-hypopnoea index (AHI) was not associated with cholesterol metabolism. Weight reduction significantly increased SaO2 and serum cholestanol and decreased AHI and serum cholestenol ratios. In the groups combined, the changes in AHI were inversely associated with changes of cholestanol and positively with cholestenol ratios independent of gender and the changes of BMI and HOMA-IR (P < 0.05). In conclusion, mild OSA seemed to be associated with cholesterol metabolism independent of BMI and HOMA-IR. Weight reduction increased the markers of cholesterol absorption and decreased those of cholesterol synthesis in the overweight subjects with mild OSA.

Figure 1

The percentage changes in apnoea-hypopnoea index (AHI), mean oxygen saturation (Sa_O2), and cholestenol and cholestanol : cholesterol ratios (10²x mmol/mol of cholesterol) in relation to changes in body weight: less than −10 kg, −10 to −5 kg, and −5 to 0 kg and more than 0 kg ^a P < 0.05 or less from weight reduction of <−10 kg, ^b P < 0.05 or less from weight reduction of −5 to 0 kg.

Figure 2

The associations between the percentage changes in apnoea-hypopnoea index (AHI) and serum cholestenol ((a), r = 0.589, P < 0.001, N = 41) and cholestanol ratios to cholesterol (10² x mmol/mol of cholesterol) ((b), r = −0.441, P = 0.004, N = 41) in the control (○) and intervention (●) groups.