LEP and cystic fibrosis: There were no differences in leptin concentration between female and male CF participants (15.78 ± 7.85 vs. 12.17 ± 5.65 ng/mL, p = 0.13) as well as healthy females and males (7.43 ± 2.7 vs. 4.97 ± 1.58 ng/mL, p = 0.116).