Co-infusion of insulin at 3–5 h significantly reduced CTRP-9 levels in healthy control (P = 0.01) and PCOS (P = 0.04) women, increased GDF-15 levels in PCOS women (P = 0.04); but had no effects on CTRP-2 levels (Table 2). Here, GDF15 is linked to polycystic ovary syndrome.