INS and polycystic ovary syndrome: When supplementation dose was taken into consideration, low dose supplementation (<50,000 IU/week) improved fasting insulin level (SMD: −0.39, 95%CI: −0.68, −0.11; Figure S1(g)), QUICKI (SMD: 0.61, 95%CI: 0.18, 1.03; Figure S1(h)), and HOMA-IR (SMD: −0.33, 95%CI: −0.63, −0.02; Figure S1(i)) in patients with PCOS.