Nature and Science of Sleep (Jan 2020)
Intramyocellular Lipids, Insulin Resistance, and Functional Performance in Patients with Severe Obstructive Sleep Apnea
Abstract
Meng-Yueh Chien, 1–3 Pei-Lin Lee, 2–5 Chih-Wei Yu, 6 Shwu Yuan Wei, 6 Tiffany Ting-Fang Shih 6 1School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan; 2Center of Sleep Disorder, National Taiwan University Hospital, Taipei, Taiwan; 3Center for Obesity, Lifestyle and Metabolic Surgery, National Taiwan University Hospital, Taipei, Taiwan; 4Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan; 5Center for Electronics Technology Integration, National Taiwan University, Taipei, Taiwan; 6Department of Medical Imaging and Radiology, Medical College and Hospital, National Taiwan University, Taipei, TaiwanCorrespondence: Tiffany Ting-Fang ShihDepartment of Medical Imaging and Radiology, Medical College and Hospital, National Taiwan University, No. 7, Chung Shan S. Road, Taipei 10002, TaiwanTel +886 2 23123456 ext 65568Email [email protected]: An increasing number of studies have linked the severity of obstructive sleep apnea (OSA) with metabolic dysfunction. However, little is known about the lipid compartments (intramyocellular [IMCL] and extramyocellular [EMCL] lipids) inside the musculature in these patients. The present study was designed to investigate the IMCL and EMCL, biochemical data, and functional performance in patients with severe OSA, and to examine the correlations between intramuscular lipid contents and test variables.Participants and Methods: Twenty patients with severe OSA (apnea-hypopnea index [AHI]: ≥ 30/h; body mass index [BMI]: 26.05± 2.92) and 20 age- and BMI-matched controls (AHI < 5/h) were enrolled. Proton magnetic resonance spectroscopy was used to measure the IMCL and EMCL of the right vastus lateralis muscle. Biochemical data, including levels of fasting plasma glucose, insulin, lipid profiles, and high-sensitivity C-reactive protein (hsCRP), were measured. Insulin resistance index (IR) was calculated using the homeostasis model assessment method. Performance tests included a cardiopulmonary exercise test and knee extension strength and endurance measurements.Results: Patients with severe OSA had significantly (P< 0.05) lower values of IMCL (14.1± 5.4 AU) and EMCL (10.3± 5.8 AU) compared to the control group (25.2± 17.6 AU and 14.3± 11.1 AU, respectively). Patients with severe OSA had significantly higher hsCRP, IR, and dyslipidemia compared with controls (all P< 0.05). Furthermore, IMCL was negatively correlated with AHI, cumulative time with nocturnal pulse oximetric saturation lower than 90% (TSpO 2< 90%) (ρ=− 0.35, P< 0.05), IR (ρ=− 0.40, P< 0.05), glucose (ρ=− 0.33, P< 0.05), and insulin (ρ=− 0.36, P< 0.05), and positively correlated with lowest oximetric saturation (ρ=0.33, P< 0.01).Conclusion: Skeletal muscle dysfunction and metabolic abnormalities were observed in patients with OSA that did not have obesity. IMCL was positively correlated with aerobic capacity and muscular performance, but negatively correlated with AHI and IR. Large-scale clinical trials are required to explore the complicated mechanism among OSA, intramuscular metabolism, and insulin action.Clinical Trial Registration: ClinicalTrials.gov Identifier: NCT00813852.Keywords: 1H magnetic resonance spectroscopy, insulin resistance, obstructive sleep apnea, skeletal muscle
