Baseline participant characteristics
| Real CPAP (n=34) | Sham CPAP (n=31) | p Value | |
| Age (years) | 51.0 (12.3) | 46.4 (10.4) | 0.11 |
| Sleep and breathing | |||
| TST (min) | 362 (308 to 400) | 378 (329 to 406) | 0.19* |
| Sleep efficiency (%) | 81.2 (67.4 to 88.7) | 85.3 (76.9 to 92.3) | 0.09* |
| REM (% TST) | 14.0 (5.0) | 17.0 (6.0) | 0.08 |
| Non-REM (% TST) | 86.0 (5.0) | 83.0 (6.0) | 0.09 |
| SWS (% TST) | 17.7 (11.3) | 21.0 (8.6) | 0.10 |
| AHI (events/h) | 38.5 (14.7) | 41.5 (20.7) | 0.79 |
| ODI3 (events/h) | 32.0 (16.8) | 34.9 (17.6) | 0.74 |
| Minimum saturation (%) | 82 (79 to 85) | 79 (74 to 84) | 0.12* |
| SpO2T90 (% TST) | 3.1 (1.0 to 5.6) | 3.6 (1.2 to 8.2) | 0.54* |
| Sleepiness | |||
| Subjective sleepiness (ESS, scale 0–24) | 10.0 (4.0) | 10.2 (4.8) | 0.82 |
| Anthropometry | |||
| Weight (kg) | 97.4 (20.7) | 94.3 (17.9) | 0.53 |
| BMI (kg/m2) | 31.6 (5.3) | 31.0 (5.1) | 0.63 |
| Waist circumference (cm) | 109.7 (13.3) | 106.3 (13.0) | 0.31 |
| Body composition | |||
| Visceral abdominal fat (cm3) | 307.4 (118.2) | 299.2 (126.0) | 0.72 |
| Subcutaneous abdominal fat (cm3) | 669.2 (239.7) | 571.1 (225.4) | 0.23 |
| Liver fat (HU) | 52.6 (13.3) | 52.9 (9.8) | 0.91 |
| L/S ratio (HU) | 1.1 (0.2) | 1.0 (0.2) | 0.19 |
| Total fat (kg) | 33.4 (12.6) | 29.9 (10.8) | 0.25 |
| Total lean muscle (kg) | 59.6 (9.1) | 59.7 (8.6) | 0.98 |
| Metabolic markers | |||
| ISx (min−1)(μU/ml)−1 | 7.1×104 (5.8×104) | 5.5×104 (4.8×104) | 0.44 |
| DI (unit) | 0.07 (0.09) | 0.05 (0.07) | 0.26 |
| HOMA (unit) | 2.9 (2.5) | 2.9 (1.8) | 0.70 |
| QUICKI (unit) | 0.3 (0.02) | 0.4 (0.05) | 0.36 |
| Fasting glucose (mmol/litre) | 5.3 (0.7) | 5.2 (0.5) | 0.56 |
| Fasting insulin (μIU/ml) | 11.8 (7.8) | 12.5 (7.7) | 0.81 |
| Adiponectin (ng/ml) | 7.3 (3.4) | 7.0 (3.6) | 0.59 |
| Leptin (ng/ml) | 15.9 (9.8) | 14.5 (10.6) | 0.58 |
| Medical history | |||
| Hypertension, n (%) | 11 (32) | 11 (35) | 0.80 |
| Using antihypertensive, n (%) | 11 (32) | 11 (35) | 0.80 |
| Hypercholesterolaemia, n (%) | 12 (35) | 12 (39) | 0.80 |
| Using statins, n (%) | 11 (32) | 7 (23) | 0.42 |
| Pre-existing CVD, n (%) | 5 (15) | 3 (10) | 0.71 |
| Glucose intolerance,† n (%) | 10 (29) | 7 (23) | 0.58 |
Values are mean (SD), median (IQR) or number (%) as appropriate. Between-group differences were assessed by t test after normalisation as required, or by rank-sum test as indicated with *.
↵† Determined by oral glucose tolerance test.
AHI, apnoea-hypopnoea index; BMI, body mass index; CPAP, continuous positive airway pressure; CVD, cardiovascular disease; DI, insulin disposition index measured by minimal model analysis; ESS, Epworth Sleepiness Scale; HOMA, homeostasis model assessment of insulin resistance; HU, Hounsfield unit; ISx, insulin sensitivity measured by minimal model analysis; L/S, liver/spleen; ODI3, oxygen desaturation index 3% pressure; QUICKI, quantitative insulin sensitivity check index; REM, rapid eye movement; SpO2T90, time that the arterial oxygen saturation was <90%; TST, total sleep time; SWS, slow wave sleep.