KL and type 2 diabetes mellitus: Furthermore, we divided the dependent variables into those with carotid atherosclerosis and those without atherosclerosis, and the results were similar to those described above, suggesting that our results were stable (Table 4, S4), and the restricted cubic splines indicated significant linear associations of both serum FGF23 levels and FGF23/α-klotho ratio with atherosclerosis (P for overall < 0.05; Fig. 2c and i), and no significant association was also found between serum α-klotho levels and T2DM combined with atherosclerosis (Fig. 2f).