FGF21 and diabetes mellitus: On the other hand, independent factors for STDR incidence were FGF21, age, diabetes duration, and diastolic blood pressure (Lin et al., 2014) divided their samples into four quartiles with different levels of FGF21, with Q1 being the lowest (FGF21 < 388 pg/mL) and Q4 being the highest (FGF21 ≥ 580 pg/mL).