Relationships of serum FGF23 and α-klotho with atherosclerosis in patients with type 2 diabetes mellitus

Background Compelling evidence suggests that calcium/phosphorus homeostasis-related parameters may be linked to diabetes mellitus and cardiovascular events. However, few studies have investigated the association of fibroblast growth factor 23 (FGF23), alpha-klotho and FGF23/alpha-klotho ratio with atherosclerosis in patients with type 2 diabetes mellitus (T2DM). Objective This study was designed to evaluate whether FGF23, alpha-klotho and FGF23/alpha-klotho ratio are associated with T2DM and further to explore the relationships between these three factors and atherosclerosis in Chinese patients with T2DM. Methods Serum FGF23 and alpha-klotho levels were measured via an enzyme-linked immunosorbent assay (ELISA) kit, and the carotid intima-media thickness (CIMT) was assessed via high-resolution color Doppler ultrasonography. The associations of serum FGF23, alpha-klotho and FGF23/alpha-klotho ratio with atherosclerosis in T2DM patients were evaluated using multivariable logistic regression models. Results This cross-sectional study involved 403 subjects (207 with T2DM and 196 without T2DM), 41.7% of the patients had atherosclerosis, and 67.2% of the carotid intima were thickened to a thickness greater than 0.9 mm. Compared with those in the lowest tertile, higher tertiles of FGF23 levels and FGF23/alpha-klotho ratio were positively associated with T2DM after adjusting for covariates, and serum alpha-klotho concentration was inversely correlated with T2DM (all P values < 0.01). Moreover, elevated serum FGF23 levels and FGF23/alpha-klotho ratio were positively associated with CIMT and carotid atherosclerosis in T2DM patients (all P values < 0.01). Further spline analysis similarly revealed linear dose-response relationship (all P values < 0.01). And there was still significant differences in CIMT and carotid atherosclerosis between the highest group of alpha-klotho and the reference group in T2DM patients (P values = 0.05). Conclusions T2DM was positively linearly related to serum FGF23 concentration and FGF23/alpha-klotho ratio, and negatively correlated with serum alpha-klotho concentration. Furthermore, both FGF23 and FGF23/alpha-klotho ratio were positively correlated with CIMT and atherosclerosis in T2DM patients, while alpha-klotho was inversely correlated with both CIMT and atherosclerosis, although the associations were not completely significant. Prospective exploration and potential mechanisms underlying these associations remain to be further elucidated.