As shown in Figure 3C, the relative level of FGF21 mRNA as measured by 2-△△CT values in the penis was significantly higher in the DMED group (2.61 ± 0.04) than in DM rats without ED (1.51 ± 0.04) and the controls (0.95 ± 0.02). Here, FGF21 is linked to diabetes mellitus.