In 50 non-diabetic humans, serum level of 15-keto-PGE2 was inversely correlated with the Homeostasis Model Assessment of Insulin resistance (HOMA-IR) index (r = −0.37, P = 0.007) (Fig. 2B), fasting glucose (r = −0.31, P = 0.02) (Fig. 2C), and fasting insulin (r = −0.33, P = 0.02) (Appendix Fig. S4). Here, INS is linked to Insulin resistance.