Effects of a lifestyle intervention on REM sleep-related OSA severity in obese individuals with type 2 diabetes

The aim of this study was to determine if an intensive lifestyle intervention (ILI) reduces the severity of obstructive sleep apnea (OSA) in rapid-eye movement (REM) sleep, and to determine if longitudinal changes in glycaemic control are related to changes in OSA severity during REM sleep over a 4-year follow-up. This was a randomized controlled trial including 264 overweight/obese adults with type 2 diabetes (T2D) and OSA. Participants were randomized to an ILI targeted to weight loss or a diabetes support and education (DSE) control group. Measures included anthropometry, apnea-hypopnea index (AHI) during REM sleep (REM-AHI) and non-REM sleep (NREM-AHI) and glycated haemoglobin (HbA1c) at baseline and year 1, year 2 and year 4 follow-ups. Mean baseline values of REM-AHI were significantly higher than NREM-AHI in both groups. Both REM-AHI and NREM-AHI were reduced significantly more in ILI versus DSE, but these differences were attenuated slightly after adjustment for weight changes. Repeated-measure mixed-model analyses including data to year 4 demonstrated that changes in HbA1c were related significantly to changes in weight, but not to changes in REM-AHI and NREM-AHI. Compared to control, the ILI reduced REM-AHI and NREM-AHI during the 4-year follow-up. Weight, as opposed to REM-AHI and NREM-AHI, was related to changes in HbA1c. The findings imply that weight loss from a lifestyle intervention is more important than reductions in AHI for improving glycaemic control in T2D patients with OSA.