Fibroblast growth factor 21 is associated with increased serum total antioxidant capacity and oxidized lipoproteins in humans with different stages of chronic kidney disease.

Background and aims: Oxidative stress (OS) induces the production of fibroblast growth factor 21 (FGF21). Previous data have revealed that FGF21 protects cells from OS injury and death, making it a potential therapeutic option for many diseases with increased OS. However, the association of this growth factor with OS markers in humans with chronic kidney disease (CKD) remains unknown. This study aims to evaluate the association of serum FGF21 with serum total antioxidant capacity (TAC) and oxidized low-density lipoproteins (OxLDL) in subjects in different stages of kidney disease. Methods: This is a cross-sectional study that included 382 subjects with different stages of CKD, irrespective of type 2 diabetes (T2D) diagnosis. Associations of serum FGF21 with OxLDL, TAC, sex, age, body mass index (BMI), fasting plasma glucose, estimated glomerular filtration rate (eGFR), T2D, and smoking, were evaluated through bivariate and partial correlation analyses. Independent associations of these variables with serum FGF21 were evaluated using multiple linear regression analysis. Results: Serum FGF21 was significantly and positively correlated with age (r = 0.236), TAC (lnTAC) (r = 0.217), and negatively correlated with eGFR (r = -0.429) and male sex (r = -0.102). After controlling by age, sex, BMI, T2D, smoking, and eGFR; both TAC and OxLDL were positively correlated with FGF21 (r = 0.117 and 0.158 respectively, p < 0.05). Using multiple linear regression analysis, eGFR, male sex, T2D, OxLDL, and TAC were independently associated with serum FGF21 (STDß = -0.475, 0.162, -0.153, 0.142 and 0.136 respectively; p < 0.05 for all) adjusted for age, BMI, smoking, and fasting plasma glucose. Conclusion: A positive association between serum FGF21 and OS has been found independently of renal function in humans. Results from the present study provide novel information for deeper understanding of the role of FGF21 in OS in humans with CKD and T2D; mechanistic studies to explain the association of serum FGF21 with oxidative stress in CKD are needed.

Serum Uric Acid concentration is associated with insulin resistance and impaired insulin secretion in adults at risk for Type 2 Diabetes.

AIMS: Insulin resistance (IR) predisposes to type 2 diabetes mellitus (T2DM). Although previous studies have associated serum uric acid concentration with IR in T2DM, its association with impaired insulin secretion and beta-cell dysfunction in subjects at risk for developing T2DM remains uncertain. Thus, we aimed to analyze the association of serum uric acid concentration with IR using surrogate insulin resistance/secretion and beta-cell function indices in subjects at risk for developing T2DM. METHODS: This is a cross-sectional study that included 354 subjects who underwent an oral glucose tolerance test who had at least two risk factors for T2DM without any chronic disease. RESULTS: Participants were 51±8 years old, 72.2% were women, had a mean body mass index of 29.9±6.5kg/m2 and mean serum uric acid concentration of 5.7±1.3mg/dL. HOMA-IR, first-phase insulin secretion (S1PhOGTT), second-phase insulin secretion (S2PhOGTT), Matsuda and disposition indices were significantly correlated with serum uric acid concentrations (r=0.239, r=0.225, r=0.201, r=-0.287, r=-0.208; respectively). After multiple linear regression analysis, serum uric acid concentration was independently associated with HOMA-IR (ß=0.283), HOMA-B (ß=0.185), S1PhOGTT (ß=0.203), S2PhOGTT (ß=0.186), and Matsuda Index (ß=-0.322). A serum uric acid concentration of 5.5mg/dL had the best sensitivity/sensibility to identify subjects with IR (HOMA-IR ≥2.5). CONCLUSIONS: Serum uric acid concentration is significantly associated with IR and impaired insulin secretion, but not with beta-cell dysfunction, in subjects at risk for developing T2DM.