LEP and rheumatoid arthritis: Leptin showed a significant positive correlation with BMI in healthy females (r = 0.66, P = 7.1 × 10−27) and males (r = 0.69, P = 1.4 × 10−17) and in patients with RA (r = 0.69, P = 2.7 × 10−155, females; r = 0.69, P = 4.7 × 10−46, males) (Fig. 1).