Lower grade chronic inflammation is associated with obstructive sleep apnea syndrome in type 2 diabetes mellitus

Abstract

To investigate whether the existence of obstructive sleep apnea syndrome (OSAS) in patients with type 2 diabetes (T2DM) is associated with low grade chronic inflammation. Fifty-four patients hospitalized for poor glycemic control from 12/2008 to 12/2009 were divided into 2 groups, OSAS group (T2DM with OSAS, 27 cases) and NOSAS group (T2DM without OSAS, 27 cases). The control group consisted of 26 people from a health check-up program without diabetes and OSAS. Biochemical indexes were analyzed in central laboratory of the hospital. Serum tumor necrosis factor-α(TNF-α), lipopolysaccharides (LPS), monocyte chemoattractant protein-1 (MCP), and plasminogen activator inhibitor-1 (PAI) levels were determined with commercial ELISA kits. Apnea hypopnea index (AHI), the lowest pulse oxygen saturation (LSpO₂) at night were measured with a portable home sleep monitor. Homeostasis model assessment insulin resistance index (HOMA-IR), AHI in OSAS group were higher than those in NOSAS group and control group [for HOMA-IR, 2.7 ± 1.5 vs 1.7 ± 0.9 vs 1.2 ± 0.7, and for AHI, (17.0 ± 13.0) vs (3.4 ± 1.3) vs (3.2 ± 1.2) per hour], and LSpO₂ was lower than that in NOSAS group and control group [(78 ± 11)% vs (87 ± 4)% vs (89 ± 6)%]. Compared with normal control, levels of TNF-α [(0.73 ± 0.19) vs (1.97 ± 0.13) vs (1.09 ± 0.29) ng/ml], LPS [(50 ± 11) vs (303 ± 70) vs (171 ± 49) pg/ml], MCP [(302 ± 41) vs (514 ± 122) vs (473 ± 134) pg/ml] and PAI [(0.89 ± 0.25) vs (2.27 ± 0.85) vs (1.59 ± 0.13) ng/ml] in patients with OSAS and with NOSAS group increased significantly. Pearson univariate correlation analysis revealed that TNF-α and PAI were both positively associated with HOMA-IR, FBG and AHI, and negatively with LSpO₂, LPS, MCP were both associated positively with FBG and AHI, and negatively with LSpO₂. Multiple linear regression stepwise analysis found that TNF-α and LPS were independently associated with AHI and FBG, MCP with LSpO₂, PAI with both AHI and HOMA-IR. Patients with diabetes and OSAS show raised level of chronic inflammatory activity.