Subgroup analyses revealed a significant leptin-lowering effect in placebo-controlled studies (SMD: −0.22; 95% CI: −0.43, −0.01, p = 0.04), but not in diabetes medications-controlled studies (SMD: −0.17; 95% CI: −0.43, 0.08, p = 0.17). Here, LEP is linked to diabetes mellitus.