Association of OSAHS Hypoxia Indicators with Early Renal Injury and Serum Fibroblast Growth Factor 21 in Obese Type 2 Diabetic Patients

OBJECTIVE: This study aimed to explore the association of obstructive sleep apnea-hypopnea syndrome (OSAHS) hypoxia indicators with early renal injury and serum fibroblast growth factor 21 (FGF21) in obese type 2 diabetic patients. METHODS: A total of 109 obese patients with type 2 diabetes mellitus (T2DM) were recruited, including 70 males and 39 females, with an average age of 52.77 ± 13.57 years and average BMI of 29.08 ± 4.36 kg/m(2). Overnight sleep monitoring was performed with a portable monitor to record respiratory parameters [apnea-hypopnea index (AHI), oxygen desaturation index (ODI), lowest oxygen saturation (LSaO(2)), mean oxygen saturation (MSaO(2)/MPO(2)) and cumulative time of oxygen saturation < 90% (CT < 90%)]. Ultrasonography was done to detect the quantitative liver fat content (LFC). The urine microalbumin and creatinine ratio (ACR) were determined by immunoturbidimetry. FGF21 was measured at baseline by enzyme-linked immunosorbent assay. Patients were divided into the proteinuria group (n = 42) and non-proteinuria group (n = 67). Correlation analysis and multivariate linear regression analysis were used to analyze the related data. In addition, patients were divided into the T2DM without OSAHS group (n = 16) and T2DM with OSAHS group (n = 93) according to the AHI value. The correlation analysis was used to assess the relationship between FGF21 and clinical variables. RESULTS: (1) ACR positively correlated with waist circumference (WC), AHI, ODI, CT < 90% and LFC, but negatively with MSaO(2) and LSaO(2). (2) AHI, ODI, CT < 90% and LFC were independent risk factors for ACR, LSaO(2) and MSaO(2) was a protective factor. (3) Serum FGF21 decreased in the OSAHS group compared with the non-OSAHS group. After adjustment for age, WC and TG, FGF21 correlated negatively with AHI, but positively with MSaO(2). CONCLUSIONS: AHI, ODI, CT < 90% and LFC are independent risk factors for ACR. FGF21 is associated with hypoxia indicators, and improving OSAHS status and reducing liver fat content may be helpful for the prevention and treatment of early diabetic nephropathy (DN). CLINICAL TRIAL REGISTRATION NUMBER: ChiCTR-IOR-15006225.